LinuxLists.cc - [PATCH v8 0/4] Introduce the for_each_set

2020-06-15 12:53:28

Subject: [PATCH v8 0/4] Introduce the for_each_set_clump macro

Hello Linus,

Since this patchset primarily affects GPIO drivers, would you like
to pick it up through your GPIO tree?

This patchset introduces a new generic version of for_each_set_clump.
The previous version of for_each_set_clump8 used a fixed size 8-bit
clump, but the new generic version can work with clump of any size but
less than or equal to BITS_PER_LONG. The patchset utilizes the new macro
in several GPIO drivers.

The earlier 8-bit for_each_set_clump8 facilitated a
for-loop syntax that iterates over a memory region entire groups of set
bits at a time.

For example, suppose you would like to iterate over a 32-bit integer 8
bits at a time, skipping over 8-bit groups with no set bit, where
XXXXXXXX represents the current 8-bit group:

Example: 10111110 00000000 11111111 00110011
First loop: 10111110 00000000 11111111 XXXXXXXX
Second loop: 10111110 00000000 XXXXXXXX 00110011
Third loop: XXXXXXXX 00000000 11111111 00110011

Each iteration of the loop returns the next 8-bit group that has at
least one set bit.

But with the new for_each_set_clump the clump size can be different from 8 bits.
Moreover, the clump can be split at word boundary in situations where word
size is not multiple of clump size. Following are examples showing the working
of new macro for clump sizes of 24 bits and 6 bits.

Example 1:
clump size: 24 bits, Number of clumps (or ports): 10
bitmap stores the bit information from where successive clumps are retrieved.

/* bitmap memory region */
0x00aa0000ff000000; /* Most significant bits */
0xaaaaaa0000ff0000;
0x000000aa000000aa;
0xbbbbabcdeffedcba; /* Least significant bits */

Different iterations of for_each_set_clump:-
'offset' is the bit position and 'clump' is the 24 bit clump from the
above bitmap.
Iteration first: offset: 0 clump: 0xfedcba
Iteration second: offset: 24 clump: 0xabcdef
Iteration third: offset: 48 clump: 0xaabbbb
Iteration fourth: offset: 96 clump: 0xaa
Iteration fifth: offset: 144 clump: 0xff
Iteration sixth: offset: 168 clump: 0xaaaaaa
Iteration seventh: offset: 216 clump: 0xff
Loop breaks because in the end the remaining bits (0x00aa) size was less
than clump size of 24 bits.

In above example it can be seen that in iteration third, the 24 bit clump
that was retrieved was split between bitmap[0] and bitmap[1]. This example
also shows that 24 bit zeroes if present in between, were skipped (preserving
the previous for_each_set_macro8 behaviour).

Example 2:
clump size = 6 bits, Number of clumps (or ports) = 3.

/* bitmap memory region */
0x00aa0000ff000000; /* Most significant bits */
0xaaaaaa0000ff0000;
0x0f00000000000000;
0x0000000000000ac0; /* Least significant bits */

Different iterations of for_each_set_clump:
'offset' is the bit position and 'clump' is the 6 bit clump from the
above bitmap.
Iteration first: offset: 6 clump: 0x2b
Loop breaks because 6 * 3 = 18 bits traversed in bitmap.
Here 6 * 3 is clump size * no. of clumps.

Changes in v8:
- [Patch 2/4]: Minor change: Use '__initdata' for correct section mismatch
in 'clump_test_data' array.

Changes in v7:
- [Patch 2/4]: Minor changes: Use macro 'DECLARE_BITMAP()' and split 'struct'
definition and test data.

Changes in v6:
- [Patch 2/4]: Make 'for loop' inside test_for_each_set_clump more
succinct.

Changes in v5:
- [Patch 4/4]: Minor change: Hardcode value for better code readability.

Changes in v4:
- [Patch 2/4]: Use 'for' loop in test function of for_each_set_clump.
- [Patch 3/4]: Minor change: Inline value for better code readability.
- [Patch 4/4]: Minor change: Inline value for better code readability.

Changes in v3:
- [Patch 3/4]: Change datatype of some variables from u64 to unsigned long
in function thunderx_gpio_set_multiple.

CHanges in v2:
- [Patch 2/4]: Unify different tests for 'for_each_set_clump'. Pass test data as
function parameters.
- [Patch 2/4]: Remove unnecessary bitmap_zero calls.

Syed Nayyar Waris (4):
bitops: Introduce the for_each_set_clump macro
lib/test_bitmap.c: Add for_each_set_clump test cases
gpio: thunderx: Utilize for_each_set_clump macro
gpio: xilinx: Utilize for_each_set_clump macro

drivers/gpio/gpio-thunderx.c | 11 ++-
drivers/gpio/gpio-xilinx.c | 62 ++++++-------
include/asm-generic/bitops/find.h | 19 ++++
include/linux/bitmap.h | 61 +++++++++++++
include/linux/bitops.h | 13 +++
lib/find_bit.c | 14 +++
lib/test_bitmap.c | 145 ++++++++++++++++++++++++++++++
7 files changed, 291 insertions(+), 34 deletions(-)

base-commit: 444fc5cde64330661bf59944c43844e7d4c2ccd8
--
2.26.2

2020-06-15 12:54:54

by Syed Nayyar Waris

[permalink] [raw]

Subject: [PATCH v8 1/4] bitops: Introduce the for_each_set_clump macro

This macro iterates for each group of bits (clump) with set bits,
within a bitmap memory region. For each iteration, "start" is set to
the bit offset of the found clump, while the respective clump value is
stored to the location pointed by "clump". Additionally, the
bitmap_get_value and bitmap_set_value functions are introduced to
respectively get and set a value of n-bits in a bitmap memory region.
The n-bits can have any size less than or equal to BITS_PER_LONG.
Moreover, during setting value of n-bit in bitmap, if a situation arise
that the width of next n-bit is exceeding the word boundary, then it
will divide itself such that some portion of it is stored in that word,
while the remaining portion is stored in the next higher word. Similar
situation occurs while retrieving value of n-bits from bitmap.

Cc: Arnd Bergmann <[email protected]>
Signed-off-by: Syed Nayyar Waris <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: William Breathitt Gray <[email protected]>
---
Changes in v8:
- No change.

Changes in v7:
- No change.

Changes in v6:
- No change.

Changes in v5:
- No change.

Changes in v4:
- No change.

Changes in v3:
- No change.

Changes in v2:
- No change.

include/asm-generic/bitops/find.h | 19 ++++++++++
include/linux/bitmap.h | 61 +++++++++++++++++++++++++++++++
include/linux/bitops.h | 13 +++++++
lib/find_bit.c | 14 +++++++
4 files changed, 107 insertions(+)

diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h
index 9fdf21302fdf..4e6600759455 100644
--- a/include/asm-generic/bitops/find.h
+++ b/include/asm-generic/bitops/find.h
@@ -97,4 +97,23 @@ extern unsigned long find_next_clump8(unsigned long *clump,
#define find_first_clump8(clump, bits, size) \
find_next_clump8((clump), (bits), (size), 0)

+/**
+ * find_next_clump - find next clump with set bits in a memory region
+ * @clump: location to store copy of found clump
+ * @addr: address to base the search on
+ * @size: bitmap size in number of bits
+ * @offset: bit offset at which to start searching
+ * @clump_size: clump size in bits
+ *
+ * Returns the bit offset for the next set clump; the found clump value is
+ * copied to the location pointed by @clump. If no bits are set, returns @size.
+ */
+extern unsigned long find_next_clump(unsigned long *clump,
+ const unsigned long *addr,
+ unsigned long size, unsigned long offset,
+ unsigned long clump_size);
+
+#define find_first_clump(clump, bits, size, clump_size) \
+ find_next_clump((clump), (bits), (size), 0, (clump_size))
+
#endif /*_ASM_GENERIC_BITOPS_FIND_H_ */
diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 99058eb81042..7ab2c65fc964 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -75,7 +75,11 @@
* bitmap_from_arr32(dst, buf, nbits) Copy nbits from u32[] buf to dst
* bitmap_to_arr32(buf, src, nbits) Copy nbits from buf to u32[] dst
* bitmap_get_value8(map, start) Get 8bit value from map at start
+ * bitmap_get_value(map, start, nbits) Get bit value of size
+ * 'nbits' from map at start
* bitmap_set_value8(map, value, start) Set 8bit value to map at start
+ * bitmap_set_value(map, value, start, nbits) Set bit value of size 'nbits'
+ * of map at start
*
* Note, bitmap_zero() and bitmap_fill() operate over the region of
* unsigned longs, that is, bits behind bitmap till the unsigned long
@@ -563,6 +567,34 @@ static inline unsigned long bitmap_get_value8(const unsigned long *map,
return (map[index] >> offset) & 0xFF;
}

+/**
+ * bitmap_get_value - get a value of n-bits from the memory region
+ * @map: address to the bitmap memory region
+ * @start: bit offset of the n-bit value
+ * @nbits: size of value in bits
+ *
+ * Returns value of nbits located at the @start bit offset within the @map
+ * memory region.
+ */
+static inline unsigned long bitmap_get_value(const unsigned long *map,
+ unsigned long start,
+ unsigned long nbits)
+{
+ const size_t index = BIT_WORD(start);
+ const unsigned long offset = start % BITS_PER_LONG;
+ const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
+ const unsigned long space = ceiling - start;
+ unsigned long value_low, value_high;
+
+ if (space >= nbits)
+ return (map[index] >> offset) & GENMASK(nbits - 1, 0);
+ else {
+ value_low = map[index] & BITMAP_FIRST_WORD_MASK(start);
+ value_high = map[index + 1] & BITMAP_LAST_WORD_MASK(start + nbits);
+ return (value_low >> offset) | (value_high << space);
+ }
+}
+
/**
* bitmap_set_value8 - set an 8-bit value within a memory region
* @map: address to the bitmap memory region
@@ -579,6 +611,35 @@ static inline void bitmap_set_value8(unsigned long *map, unsigned long value,
map[index] |= value << offset;
}

+/**
+ * bitmap_set_value - set n-bit value within a memory region
+ * @map: address to the bitmap memory region
+ * @value: value of nbits
+ * @start: bit offset of the n-bit value
+ * @nbits: size of value in bits
+ */
+static inline void bitmap_set_value(unsigned long *map,
+ unsigned long value,
+ unsigned long start, unsigned long nbits)
+{
+ const size_t index = BIT_WORD(start);
+ const unsigned long offset = start % BITS_PER_LONG;
+ const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
+ const unsigned long space = ceiling - start;
+
+ value &= GENMASK(nbits - 1, 0);
+
+ if (space >= nbits) {
+ map[index] &= ~(GENMASK(nbits + offset - 1, offset));
+ map[index] |= value << offset;
+ } else {
+ map[index] &= ~BITMAP_FIRST_WORD_MASK(start);
+ map[index] |= value << offset;
+ map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits);
+ map[index + 1] |= (value >> space);
+ }
+}
+
#endif /* __ASSEMBLY__ */

#endif /* __LINUX_BITMAP_H */
diff --git a/include/linux/bitops.h b/include/linux/bitops.h
index 9acf654f0b19..41c2d9ce63e7 100644
--- a/include/linux/bitops.h
+++ b/include/linux/bitops.h
@@ -62,6 +62,19 @@ extern unsigned long __sw_hweight64(__u64 w);
(start) < (size); \
(start) = find_next_clump8(&(clump), (bits), (size), (start) + 8))

+/**
+ * for_each_set_clump - iterate over bitmap for each clump with set bits
+ * @start: bit offset to start search and to store the current iteration offset
+ * @clump: location to store copy of current 8-bit clump
+ * @bits: bitmap address to base the search on
+ * @size: bitmap size in number of bits
+ * @clump_size: clump size in bits
+ */
+#define for_each_set_clump(start, clump, bits, size, clump_size) \
+ for ((start) = find_first_clump(&(clump), (bits), (size), (clump_size)); \
+ (start) < (size); \
+ (start) = find_next_clump(&(clump), (bits), (size), (start) + (clump_size), (clump_size)))
+
static inline int get_bitmask_order(unsigned int count)
{
int order;
diff --git a/lib/find_bit.c b/lib/find_bit.c
index 49f875f1baf7..1341bd39b32a 100644
--- a/lib/find_bit.c
+++ b/lib/find_bit.c
@@ -190,3 +190,17 @@ unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
return offset;
}
EXPORT_SYMBOL(find_next_clump8);
+
+unsigned long find_next_clump(unsigned long *clump, const unsigned long *addr,
+ unsigned long size, unsigned long offset,
+ unsigned long clump_size)
+{
+ offset = find_next_bit(addr, size, offset);
+ if (offset == size)
+ return size;
+
+ offset = rounddown(offset, clump_size);
+ *clump = bitmap_get_value(addr, offset, clump_size);
+ return offset;
+}
+EXPORT_SYMBOL(find_next_clump);
--
2.26.2

2020-06-15 12:55:07

by Syed Nayyar Waris

[permalink] [raw]

Subject: [PATCH v8 2/4] lib/test_bitmap.c: Add for_each_set_clump test cases

The introduction of the generic for_each_set_clump macro need test
cases to verify the implementation. This patch adds test cases for
scenarios in which clump sizes are 8 bits, 24 bits, 30 bits and 6 bits.
The cases contain situations where clump is getting split at the word
boundary and also when zeroes are present in the start and middle of
bitmap.

Signed-off-by: Syed Nayyar Waris <[email protected]>
Reviewed-by: Andy Shevchenko <[email protected]>
Signed-off-by: William Breathitt Gray <[email protected]>
---
Changes in v8:
- [Patch 2/4]: Minor change: Use '__initdata' for correct section mismatch
in 'clump_test_data' array.

Changes in v7:
- Minor changes: Use macro 'DECLARE_BITMAP()' and split 'struct'
definition and test data.

Changes in v6:
- Make 'for loop' inside 'test_for_each_set_clump' more succinct.

Changes in v5:
- No change.

Changes in v4:
- Use 'for' loop in test function of 'for_each_set_clump'.

Changes in v3:
- No Change.

Changes in v2:
- Unify different tests for 'for_each_set_clump'. Pass test data as
function parameters.
- Remove unnecessary bitmap_zero calls.

lib/test_bitmap.c | 145 ++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 145 insertions(+)

diff --git a/lib/test_bitmap.c b/lib/test_bitmap.c
index 6b13150667f5..78c0048870a6 100644
--- a/lib/test_bitmap.c
+++ b/lib/test_bitmap.c
@@ -155,6 +155,38 @@ static bool __init __check_eq_clump8(const char *srcfile, unsigned int line,
return true;
}

+static bool __init __check_eq_clump(const char *srcfile, unsigned int line,
+ const unsigned int offset,
+ const unsigned int size,
+ const unsigned long *const clump_exp,
+ const unsigned long *const clump,
+ const unsigned long clump_size)
+{
+ unsigned long exp;
+
+ if (offset >= size) {
+ pr_warn("[%s:%u] bit offset for clump out-of-bounds: expected less than %u, got %u\n",
+ srcfile, line, size, offset);
+ return false;
+ }
+
+ exp = clump_exp[offset / clump_size];
+ if (!exp) {
+ pr_warn("[%s:%u] bit offset for zero clump: expected nonzero clump, got bit offset %u with clump value 0",
+ srcfile, line, offset);
+ return false;
+ }
+
+ if (*clump != exp) {
+ pr_warn("[%s:%u] expected clump value of 0x%lX, got clump value of 0x%lX",
+ srcfile, line, exp, *clump);
+ return false;
+ }
+
+ return true;
+}
+
+
#define __expect_eq(suffix, ...) \
({ \
int result = 0; \
@@ -172,6 +204,7 @@ static bool __init __check_eq_clump8(const char *srcfile, unsigned int line,
#define expect_eq_pbl(...) __expect_eq(pbl, ##__VA_ARGS__)
#define expect_eq_u32_array(...) __expect_eq(u32_array, ##__VA_ARGS__)
#define expect_eq_clump8(...) __expect_eq(clump8, ##__VA_ARGS__)
+#define expect_eq_clump(...) __expect_eq(clump, ##__VA_ARGS__)

static void __init test_zero_clear(void)
{
@@ -577,6 +610,28 @@ static void noinline __init test_mem_optimisations(void)
}
}

+static const unsigned long clump_bitmap_data[] __initconst = {
+ 0x38000201,
+ 0x05ff0f38,
+ 0xeffedcba,
+ 0xbbbbabcd,
+ 0x000000aa,
+ 0x000000aa,
+ 0x00ff0000,
+ 0xaaaaaa00,
+ 0xff000000,
+ 0x00aa0000,
+ 0x00000000,
+ 0x00000000,
+ 0x00000000,
+ 0x0f000000,
+ 0x00ff0000,
+ 0xaaaaaa00,
+ 0xff000000,
+ 0x00aa0000,
+ 0x00000ac0,
+};
+
static const unsigned char clump_exp[] __initconst = {
0x01, /* 1 bit set */
0x02, /* non-edge 1 bit set */
@@ -588,6 +643,95 @@ static const unsigned char clump_exp[] __initconst = {
0x05, /* non-adjacent 2 bits set */
};

+static const unsigned long clump_exp1[] __initconst = {
+ 0x01, /* 1 bit set */
+ 0x02, /* non-edge 1 bit set */
+ 0x00, /* zero bits set */
+ 0x38, /* 3 bits set across 4-bit boundary */
+ 0x38, /* Repeated clump */
+ 0x0F, /* 4 bits set */
+ 0xFF, /* all bits set */
+ 0x05, /* non-adjacent 2 bits set */
+};
+
+static const unsigned long clump_exp2[] __initconst = {
+ 0xfedcba, /* 24 bits */
+ 0xabcdef,
+ 0xaabbbb, /* Clump split between 2 words */
+ 0x000000, /* zeroes in between */
+ 0x0000aa,
+ 0x000000,
+ 0x0000ff,
+ 0xaaaaaa,
+ 0x000000,
+ 0x0000ff,
+};
+
+static const unsigned long clump_exp3[] __initconst = {
+ 0x00000000, /* starting with 0s*/
+ 0x00000000, /* All 0s */
+ 0x00000000,
+ 0x00000000,
+ 0x3f00000f, /* Non zero set */
+ 0x2aa80003,
+ 0x00000aaa,
+ 0x00003fc0,
+};
+
+static const unsigned long clump_exp4[] __initconst = {
+ 0x00,
+ 0x2b,
+};
+
+struct clump_test_data_params {
+ DECLARE_BITMAP(data, 256);
+ unsigned long count;
+ unsigned long offset;
+ unsigned long limit;
+ unsigned long clump_size;
+ unsigned long const *exp;
+};
+
+static struct clump_test_data_params clump_test_data[] __initdata =
+ { {{0}, 2, 0, 64, 8, clump_exp1},
+ {{0}, 8, 2, 240, 24, clump_exp2},
+ {{0}, 8, 10, 240, 30, clump_exp3},
+ {{0}, 1, 18, 18, 6, clump_exp4} };
+
+static void __init prepare_test_data(unsigned int index)
+{
+ int i;
+ unsigned long width = 0;
+
+ for(i = 0; i < clump_test_data[index].count; i++)
+ {
+ bitmap_set_value(clump_test_data[index].data,
+ clump_bitmap_data[(clump_test_data[index].offset)++], width, 32);
+ width += 32;
+ }
+}
+
+static void __init execute_for_each_set_clump_test(unsigned int index)
+{
+ unsigned long start, clump;
+
+ for_each_set_clump(start, clump, clump_test_data[index].data,
+ clump_test_data[index].limit,
+ clump_test_data[index].clump_size)
+ expect_eq_clump(start, clump_test_data[index].limit, clump_test_data[index].exp,
+ &clump, clump_test_data[index].clump_size);
+}
+
+static void __init test_for_each_set_clump(void)
+{
+ unsigned int i;
+
+ for (i = 0; i < ARRAY_SIZE(clump_test_data); i++) {
+ prepare_test_data(i);
+ execute_for_each_set_clump_test(i);
+ }
+}
+
static void __init test_for_each_set_clump8(void)
{
#define CLUMP_EXP_NUMBITS 64
@@ -623,6 +767,7 @@ static void __init selftest(void)
test_bitmap_parselist_user();
test_mem_optimisations();
test_for_each_set_clump8();
+ test_for_each_set_clump();
}

KSTM_MODULE_LOADERS(test_bitmap);
--
2.26.2

2020-06-15 12:58:03

by Syed Nayyar Waris

[permalink] [raw]

Subject: [PATCH v8 4/4] gpio: xilinx: Utilize for_each_set_clump macro

This patch reimplements the xgpio_set_multiple function in
drivers/gpio/gpio-xilinx.c to use the new for_each_set_clump macro.
Instead of looping for each bit in xgpio_set_multiple
function, now we can check each channel at a time and save cycles.

Cc: Bartosz Golaszewski <[email protected]>
Cc: Michal Simek <[email protected]>
Signed-off-by: Syed Nayyar Waris <[email protected]>
Signed-off-by: William Breathitt Gray <[email protected]>
---
Changes in v8:
- No change.

Changes in v7:
- No change.

Changes in v6:
- No change.

Changes in v5:
- Minor change: Inline values '32' and '64' in code for better
code readability.

Changes in v4:
- Minor change: Inline values '32' and '64' in code for better
code readability.

Changes in v3:
- No change.

Changes in v2:
- No change.

drivers/gpio/gpio-xilinx.c | 62 ++++++++++++++++++++------------------
1 file changed, 32 insertions(+), 30 deletions(-)

diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
index 67f9f82e0db0..e81092dea27e 100644
--- a/drivers/gpio/gpio-xilinx.c
+++ b/drivers/gpio/gpio-xilinx.c
@@ -136,39 +136,41 @@ static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
static void xgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
unsigned long *bits)
{
- unsigned long flags;
+ unsigned long flags[2];
struct xgpio_instance *chip = gpiochip_get_data(gc);
- int index = xgpio_index(chip, 0);
- int offset, i;
-
- spin_lock_irqsave(&chip->gpio_lock[index], flags);
-
- /* Write to GPIO signals */
- for (i = 0; i < gc->ngpio; i++) {
- if (*mask == 0)
- break;
- /* Once finished with an index write it out to the register */
- if (index != xgpio_index(chip, i)) {
- xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
- index * XGPIO_CHANNEL_OFFSET,
- chip->gpio_state[index]);
- spin_unlock_irqrestore(&chip->gpio_lock[index], flags);
- index = xgpio_index(chip, i);
- spin_lock_irqsave(&chip->gpio_lock[index], flags);
- }
- if (__test_and_clear_bit(i, mask)) {
- offset = xgpio_offset(chip, i);
- if (test_bit(i, bits))
- chip->gpio_state[index] |= BIT(offset);
- else
- chip->gpio_state[index] &= ~BIT(offset);
- }
+ u32 *const state = chip->gpio_state;
+ unsigned int *const width = chip->gpio_width;
+ unsigned long offset, clump;
+ size_t index;
+
+ DECLARE_BITMAP(old, 64);
+ DECLARE_BITMAP(new, 64);
+ DECLARE_BITMAP(changed, 64);
+
+ spin_lock_irqsave(&chip->gpio_lock[0], flags[0]);
+ spin_lock_irqsave(&chip->gpio_lock[1], flags[1]);
+
+ bitmap_set_value(old, state[0], 0, width[0]);
+ bitmap_set_value(old, state[1], width[0], width[1]);
+ bitmap_replace(new, old, bits, mask, gc->ngpio);
+
+ bitmap_set_value(old, state[0], 0, 32);
+ bitmap_set_value(old, state[1], 32, 32);
+ state[0] = bitmap_get_value(new, 0, width[0]);
+ state[1] = bitmap_get_value(new, width[0], width[1]);
+ bitmap_set_value(new, state[0], 0, 32);
+ bitmap_set_value(new, state[1], 32, 32);
+ bitmap_xor(changed, old, new, 64);
+
+ for_each_set_clump(offset, clump, changed, 64, 32) {
+ index = offset / 32;
+ xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
+ index * XGPIO_CHANNEL_OFFSET,
+ state[index]);
}

- xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
- index * XGPIO_CHANNEL_OFFSET, chip->gpio_state[index]);
-
- spin_unlock_irqrestore(&chip->gpio_lock[index], flags);
+ spin_unlock_irqrestore(&chip->gpio_lock[1], flags[1]);
+ spin_unlock_irqrestore(&chip->gpio_lock[0], flags[0]);
}

/**
--
2.26.2

2020-06-15 12:58:51

by Syed Nayyar Waris

[permalink] [raw]

Subject: [PATCH v8 3/4] gpio: thunderx: Utilize for_each_set_clump macro

This patch reimplements the thunderx_gpio_set_multiple function in
drivers/gpio/gpio-thunderx.c to use the new for_each_set_clump macro.
Instead of looping for each bank in thunderx_gpio_set_multiple
function, now we can skip bank which is not set and save cycles.

Cc: Robert Richter <[email protected]>
Cc: Bartosz Golaszewski <[email protected]>
Signed-off-by: Syed Nayyar Waris <[email protected]>
Signed-off-by: William Breathitt Gray <[email protected]>
---
Changes in v8:
- No change.

Changes in v7:
- No change.

Changes in v6:
- No change.

Changes in v5:
- No change.

Changes in v4:
- Minor change: Inline value '64' in code for better code readability.

Changes in v3:
- Change datatype of some variables from u64 to unsigned long
in function thunderx_gpio_set_multiple.

Changes in v2:
- No change.

drivers/gpio/gpio-thunderx.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/drivers/gpio/gpio-thunderx.c b/drivers/gpio/gpio-thunderx.c
index 9f66deab46ea..58c9bb25a377 100644
--- a/drivers/gpio/gpio-thunderx.c
+++ b/drivers/gpio/gpio-thunderx.c
@@ -275,12 +275,15 @@ static void thunderx_gpio_set_multiple(struct gpio_chip *chip,
unsigned long *bits)
{
int bank;
- u64 set_bits, clear_bits;
+ unsigned long set_bits, clear_bits, gpio_mask;
+ unsigned long offset;
+
struct thunderx_gpio *txgpio = gpiochip_get_data(chip);

- for (bank = 0; bank <= chip->ngpio / 64; bank++) {
- set_bits = bits[bank] & mask[bank];
- clear_bits = ~bits[bank] & mask[bank];
+ for_each_set_clump(offset, gpio_mask, mask, chip->ngpio, 64) {
+ bank = offset / 64;
+ set_bits = bits[bank] & gpio_mask;
+ clear_bits = ~bits[bank] & gpio_mask;
writeq(set_bits, txgpio->register_base + (bank * GPIO_2ND_BANK) + GPIO_TX_SET);
writeq(clear_bits, txgpio->register_base + (bank * GPIO_2ND_BANK) + GPIO_TX_CLR);
}
--
2.26.2

2020-06-15 13:59:11

by Andy Shevchenko

[permalink] [raw]

Subject: Re: [PATCH v8 1/4] bitops: Introduce the for_each_set_clump macro

On Mon, Jun 15, 2020 at 06:21:18PM +0530, Syed Nayyar Waris wrote:
> This macro iterates for each group of bits (clump) with set bits,
> within a bitmap memory region. For each iteration, "start" is set to
> the bit offset of the found clump, while the respective clump value is
> stored to the location pointed by "clump". Additionally, the
> bitmap_get_value and bitmap_set_value functions are introduced to
> respectively get and set a value of n-bits in a bitmap memory region.
> The n-bits can have any size less than or equal to BITS_PER_LONG.
> Moreover, during setting value of n-bit in bitmap, if a situation arise
> that the width of next n-bit is exceeding the word boundary, then it
> will divide itself such that some portion of it is stored in that word,
> while the remaining portion is stored in the next higher word. Similar
> situation occurs while retrieving value of n-bits from bitmap.
>
> Cc: Arnd Bergmann <[email protected]>
> Signed-off-by: Syed Nayyar Waris <[email protected]>
> Reviewed-by: Andy Shevchenko <[email protected]>
> Signed-off-by: William Breathitt Gray <[email protected]>
> ---
> Changes in v8:
> - No change.
>
> Changes in v7:
> - No change.
>
> Changes in v6:
> - No change.
>
> Changes in v5:
> - No change.
>
> Changes in v4:
> - No change.
>
> Changes in v3:
> - No change.
>
> Changes in v2:
> - No change.
>
> include/asm-generic/bitops/find.h | 19 ++++++++++
> include/linux/bitmap.h | 61 +++++++++++++++++++++++++++++++
> include/linux/bitops.h | 13 +++++++
> lib/find_bit.c | 14 +++++++
> 4 files changed, 107 insertions(+)
>
> diff --git a/include/asm-generic/bitops/find.h b/include/asm-generic/bitops/find.h
> index 9fdf21302fdf..4e6600759455 100644
> --- a/include/asm-generic/bitops/find.h
> +++ b/include/asm-generic/bitops/find.h
> @@ -97,4 +97,23 @@ extern unsigned long find_next_clump8(unsigned long *clump,
> #define find_first_clump8(clump, bits, size) \
> find_next_clump8((clump), (bits), (size), 0)
>
> +/**
> + * find_next_clump - find next clump with set bits in a memory region
> + * @clump: location to store copy of found clump
> + * @addr: address to base the search on
> + * @size: bitmap size in number of bits
> + * @offset: bit offset at which to start searching
> + * @clump_size: clump size in bits
> + *
> + * Returns the bit offset for the next set clump; the found clump value is
> + * copied to the location pointed by @clump. If no bits are set, returns @size.
> + */
> +extern unsigned long find_next_clump(unsigned long *clump,
> + const unsigned long *addr,
> + unsigned long size, unsigned long offset,
> + unsigned long clump_size);
> +
> +#define find_first_clump(clump, bits, size, clump_size) \
> + find_next_clump((clump), (bits), (size), 0, (clump_size))
> +
> #endif /*_ASM_GENERIC_BITOPS_FIND_H_ */
> diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
> index 99058eb81042..7ab2c65fc964 100644
> --- a/include/linux/bitmap.h
> +++ b/include/linux/bitmap.h
> @@ -75,7 +75,11 @@
> * bitmap_from_arr32(dst, buf, nbits) Copy nbits from u32[] buf to dst
> * bitmap_to_arr32(buf, src, nbits) Copy nbits from buf to u32[] dst
> * bitmap_get_value8(map, start) Get 8bit value from map at start
> + * bitmap_get_value(map, start, nbits) Get bit value of size
> + * 'nbits' from map at start
> * bitmap_set_value8(map, value, start) Set 8bit value to map at start
> + * bitmap_set_value(map, value, start, nbits) Set bit value of size 'nbits'
> + * of map at start
> *
> * Note, bitmap_zero() and bitmap_fill() operate over the region of
> * unsigned longs, that is, bits behind bitmap till the unsigned long
> @@ -563,6 +567,34 @@ static inline unsigned long bitmap_get_value8(const unsigned long *map,
> return (map[index] >> offset) & 0xFF;
> }
>
> +/**
> + * bitmap_get_value - get a value of n-bits from the memory region
> + * @map: address to the bitmap memory region
> + * @start: bit offset of the n-bit value
> + * @nbits: size of value in bits
> + *
> + * Returns value of nbits located at the @start bit offset within the @map
> + * memory region.
> + */
> +static inline unsigned long bitmap_get_value(const unsigned long *map,
> + unsigned long start,
> + unsigned long nbits)
> +{
> + const size_t index = BIT_WORD(start);
> + const unsigned long offset = start % BITS_PER_LONG;
> + const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
> + const unsigned long space = ceiling - start;
> + unsigned long value_low, value_high;
> +
> + if (space >= nbits)
> + return (map[index] >> offset) & GENMASK(nbits - 1, 0);

Andrew, note that this requires to have GENMASK() fix [1] applied.

[1]: https://lore.kernel.org/lkml/[email protected]/

> + else {
> + value_low = map[index] & BITMAP_FIRST_WORD_MASK(start);
> + value_high = map[index + 1] & BITMAP_LAST_WORD_MASK(start + nbits);
> + return (value_low >> offset) | (value_high << space);
> + }
> +}
> +
> /**
> * bitmap_set_value8 - set an 8-bit value within a memory region
> * @map: address to the bitmap memory region
> @@ -579,6 +611,35 @@ static inline void bitmap_set_value8(unsigned long *map, unsigned long value,
> map[index] |= value << offset;
> }
>
> +/**
> + * bitmap_set_value - set n-bit value within a memory region
> + * @map: address to the bitmap memory region
> + * @value: value of nbits
> + * @start: bit offset of the n-bit value
> + * @nbits: size of value in bits
> + */
> +static inline void bitmap_set_value(unsigned long *map,
> + unsigned long value,
> + unsigned long start, unsigned long nbits)
> +{
> + const size_t index = BIT_WORD(start);
> + const unsigned long offset = start % BITS_PER_LONG;
> + const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
> + const unsigned long space = ceiling - start;
> +
> + value &= GENMASK(nbits - 1, 0);
> +
> + if (space >= nbits) {
> + map[index] &= ~(GENMASK(nbits + offset - 1, offset));
> + map[index] |= value << offset;
> + } else {
> + map[index] &= ~BITMAP_FIRST_WORD_MASK(start);
> + map[index] |= value << offset;
> + map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits);
> + map[index + 1] |= (value >> space);
> + }
> +}
> +
> #endif /* __ASSEMBLY__ */
>
> #endif /* __LINUX_BITMAP_H */
> diff --git a/include/linux/bitops.h b/include/linux/bitops.h
> index 9acf654f0b19..41c2d9ce63e7 100644
> --- a/include/linux/bitops.h
> +++ b/include/linux/bitops.h
> @@ -62,6 +62,19 @@ extern unsigned long __sw_hweight64(__u64 w);
> (start) < (size); \
> (start) = find_next_clump8(&(clump), (bits), (size), (start) + 8))
>
> +/**
> + * for_each_set_clump - iterate over bitmap for each clump with set bits
> + * @start: bit offset to start search and to store the current iteration offset
> + * @clump: location to store copy of current 8-bit clump
> + * @bits: bitmap address to base the search on
> + * @size: bitmap size in number of bits
> + * @clump_size: clump size in bits
> + */
> +#define for_each_set_clump(start, clump, bits, size, clump_size) \
> + for ((start) = find_first_clump(&(clump), (bits), (size), (clump_size)); \
> + (start) < (size); \
> + (start) = find_next_clump(&(clump), (bits), (size), (start) + (clump_size), (clump_size)))
> +
> static inline int get_bitmask_order(unsigned int count)
> {
> int order;
> diff --git a/lib/find_bit.c b/lib/find_bit.c
> index 49f875f1baf7..1341bd39b32a 100644
> --- a/lib/find_bit.c
> +++ b/lib/find_bit.c
> @@ -190,3 +190,17 @@ unsigned long find_next_clump8(unsigned long *clump, const unsigned long *addr,
> return offset;
> }
> EXPORT_SYMBOL(find_next_clump8);
> +
> +unsigned long find_next_clump(unsigned long *clump, const unsigned long *addr,
> + unsigned long size, unsigned long offset,
> + unsigned long clump_size)
> +{
> + offset = find_next_bit(addr, size, offset);
> + if (offset == size)
> + return size;
> +
> + offset = rounddown(offset, clump_size);
> + *clump = bitmap_get_value(addr, offset, clump_size);
> + return offset;
> +}
> +EXPORT_SYMBOL(find_next_clump);
> --
> 2.26.2
>

--
With Best Regards,
Andy Shevchenko

2020-06-15 16:53:15

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH v8 1/4] bitops: Introduce the for_each_set_clump macro

Hi Syed,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on 444fc5cde64330661bf59944c43844e7d4c2ccd8]

url: https://github.com/0day-ci/linux/commits/Syed-Nayyar-Waris/Introduce-the-for_each_set_clump-macro/20200615-205729
base: 444fc5cde64330661bf59944c43844e7d4c2ccd8
config: ia64-randconfig-r003-20200615 (attached as .config)
compiler: ia64-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=ia64

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>

All warnings (new ones prefixed by >>, old ones prefixed by <<):

scripts/Makefile.build:59: 'arch/ia64/kernel/palinfo.ko' 'arch/ia64/kernel/mca_recovery.ko' 'arch/ia64/kernel/err_inject.ko' will not be built even though obj-m is specified.
scripts/Makefile.build:60: You cannot use subdir-y/m to visit a module Makefile. Use obj-y/m instead.
In file included from include/linux/bits.h:23,
from include/linux/bitops.h:5,
from include/linux/kernel.h:12,
from include/linux/list.h:9,
from include/linux/rculist.h:10,
from include/linux/sched/signal.h:5,
from arch/ia64/kernel/asm-offsets.c:10:
include/linux/bitmap.h: In function 'bitmap_get_value':
include/linux/bits.h:26:28: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
>> include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
>> include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bitmap.h: In function 'bitmap_set_value':
include/linux/bits.h:26:28: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
In file included from arch/ia64/include/asm/pgtable.h:154,
from arch/ia64/include/asm/uaccess.h:40,
from include/linux/uaccess.h:11,
from include/linux/sched/task.h:11,
from include/linux/sched/signal.h:9,
from arch/ia64/kernel/asm-offsets.c:10:
arch/ia64/include/asm/mmu_context.h: In function 'reload_context':
arch/ia64/include/asm/mmu_context.h:137:41: warning: variable 'old_rr4' set but not used [-Wunused-but-set-variable]
137 | unsigned long rr0, rr1, rr2, rr3, rr4, old_rr4;
| ^~~~~~~
arch/ia64/kernel/asm-offsets.c: At top level:
arch/ia64/kernel/asm-offsets.c:23:6: warning: no previous prototype for 'foo' [-Wmissing-prototypes]
23 | void foo(void)
| ^~~
<stdin>:1511:2: warning: #warning syscall clone3 not implemented [-Wcpp]

vim +/GENMASK +590 include/linux/bitmap.h

569
570 /**
571 * bitmap_get_value - get a value of n-bits from the memory region
572 * @map: address to the bitmap memory region
573 * @start: bit offset of the n-bit value
574 * @nbits: size of value in bits
575 *
576 * Returns value of nbits located at the @start bit offset within the @map
577 * memory region.
578 */
579 static inline unsigned long bitmap_get_value(const unsigned long *map,
580 unsigned long start,
581 unsigned long nbits)
582 {
583 const size_t index = BIT_WORD(start);
584 const unsigned long offset = start % BITS_PER_LONG;
585 const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
586 const unsigned long space = ceiling - start;
587 unsigned long value_low, value_high;
588
589 if (space >= nbits)
> 590 return (map[index] >> offset) & GENMASK(nbits - 1, 0);
591 else {
592 value_low = map[index] & BITMAP_FIRST_WORD_MASK(start);
593 value_high = map[index + 1] & BITMAP_LAST_WORD_MASK(start + nbits);
594 return (value_low >> offset) | (value_high << space);
595 }
596 }
597

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

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2020-06-15 20:15:57

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH v8 4/4] gpio: xilinx: Utilize for_each_set_clump macro

Attachments:

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2020-06-16 05:59:56

by Syed Nayyar Waris

[permalink] [raw]

Subject: Re: [PATCH v8 4/4] gpio: xilinx: Utilize for_each_set_clump macro

On Tue, Jun 16, 2020 at 1:39 AM kernel test robot <[email protected]> wrote:
>
> Hi Syed,
>
> Thank you for the patch! Perhaps something to improve:
>
> [auto build test WARNING on 444fc5cde64330661bf59944c43844e7d4c2ccd8]
>
> url: https://github.com/0day-ci/linux/commits/Syed-Nayyar-Waris/Introduce-the-for_each_set_clump-macro/20200615-205729
> base: 444fc5cde64330661bf59944c43844e7d4c2ccd8
> config: sparc64-randconfig-s032-20200615 (attached as .config)
> compiler: sparc64-linux-gcc (GCC) 9.3.0
> reproduce:
> # apt-get install sparse
> # sparse version: v0.6.2-rc1-3-g55607964-dirty
> # save the attached .config to linux build tree
> make W=1 C=1 ARCH=sparc64 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <[email protected]>
>
>
> sparse warnings: (new ones prefixed by >>)
>
> >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> include/linux/bitmap.h:594:63: sparse: sparse: shift too big (64) for type unsigned long
> >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> >> include/linux/bitmap.h:638:17: sparse: sparse: invalid access past the end of 'old' (8 8)
>
> vim +639 include/linux/bitmap.h
>
> 169c474fb22d8a William Breathitt Gray 2019-12-04 613
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 614 /**
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 615 * bitmap_set_value - set n-bit value within a memory region
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 616 * @map: address to the bitmap memory region
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 617 * @value: value of nbits
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 618 * @start: bit offset of the n-bit value
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 619 * @nbits: size of value in bits
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 620 */
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 621 static inline void bitmap_set_value(unsigned long *map,
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 622 unsigned long value,
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 623 unsigned long start, unsigned long nbits)
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 624 {
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 625 const size_t index = BIT_WORD(start);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 626 const unsigned long offset = start % BITS_PER_LONG;
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 627 const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 628 const unsigned long space = ceiling - start;
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 629
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 630 value &= GENMASK(nbits - 1, 0);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 631
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 632 if (space >= nbits) {
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 633 map[index] &= ~(GENMASK(nbits + offset - 1, offset));
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 634 map[index] |= value << offset;
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 635 } else {
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 636 map[index] &= ~BITMAP_FIRST_WORD_MASK(start);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 637 map[index] |= value << offset;
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 @638 map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 @639 map[index + 1] |= (value >> space);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 640 }
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 641 }
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 642

Regarding the compilation warning reported above:

"sparse: shift too big (64) for type unsigned long" at line 639
"sparse: invalid access past the end of 'old' (8 8)" at line 638

Kindly refer to the code above, at these line numbers.

I am in the process of fixing this warning. But what would be the fix
? At the moment can't think of a code-fix to make the compilation
warning disappear (specially at line 639). Can anyone please explain
to me the meaning of the compilation warning more deeply?

By the way, this warning was not reported in (earlier) v7 of the patchset.

Regards
Syed Nayyar Waris

2020-06-16 08:16:52

by Andy Shevchenko

[permalink] [raw]

Subject: Re: [PATCH v8 1/4] bitops: Introduce the for_each_set_clump macro

2020-06-17 08:45:59

by kernel test robot

[permalink] [raw]

Subject: Re: [PATCH v8 1/4] bitops: Introduce the for_each_set_clump macro

Hi Syed,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on 444fc5cde64330661bf59944c43844e7d4c2ccd8]

url: https://github.com/0day-ci/linux/commits/Syed-Nayyar-Waris/Introduce-the-for_each_set_clump-macro/20200615-205729
base: 444fc5cde64330661bf59944c43844e7d4c2ccd8
config: x86_64-rhel (attached as .config)
compiler: gcc-9 (Debian 9.3.0-13) 9.3.0
reproduce (this is a W=1 build):
# save the attached .config to linux build tree
make W=1 ARCH=x86_64

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>

All errors (new ones prefixed by >>, old ones prefixed by <<):

In file included from include/linux/bits.h:23,
from include/linux/bitops.h:5,
from include/linux/kernel.h:12,
from include/linux/list.h:9,
from include/linux/preempt.h:11,
from include/linux/hardirq.h:5,
from include/linux/kvm_host.h:7,
from arch/x86/kvm/../../../virt/kvm/kvm_main.c:18:
include/linux/bitmap.h: In function 'bitmap_get_value':
>> include/linux/bits.h:26:28: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bitmap.h: In function 'bitmap_set_value':
>> include/linux/bits.h:26:28: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
cc1: all warnings being treated as errors
--
In file included from include/linux/bits.h:23,
from include/linux/bitops.h:5,
from include/linux/kernel.h:12,
from include/linux/list.h:9,
from include/linux/preempt.h:11,
from include/linux/hardirq.h:5,
from include/linux/kvm_host.h:7,
from arch/x86/kvm/../../../virt/kvm/irqchip.c:15:
include/linux/bitmap.h: In function 'bitmap_get_value':
>> include/linux/bits.h:26:28: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bitmap.h: In function 'bitmap_set_value':
>> include/linux/bits.h:26:28: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
arch/x86/kvm/../../../virt/kvm/irqchip.c: At top level:
arch/x86/kvm/../../../virt/kvm/irqchip.c:20:10: fatal error: irq.h: No such file or directory
20 | #include "irq.h"
| ^~~~~~~
cc1: all warnings being treated as errors
compilation terminated.
--
In file included from include/linux/bits.h:23,
from include/linux/bitops.h:5,
from include/linux/kernel.h:12,
from include/linux/list.h:9,
from include/linux/preempt.h:11,
from include/linux/hardirq.h:5,
from include/linux/kvm_host.h:7,
from arch/x86/kvm/mmu/page_track.c:14:
include/linux/bitmap.h: In function 'bitmap_get_value':
>> include/linux/bits.h:26:28: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bitmap.h: In function 'bitmap_set_value':
>> include/linux/bits.h:26:28: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
arch/x86/kvm/mmu/page_track.c: At top level:
arch/x86/kvm/mmu/page_track.c:19:10: fatal error: mmu.h: No such file or directory
19 | #include "mmu.h"
| ^~~~~~~
cc1: all warnings being treated as errors
compilation terminated.
--
In file included from include/linux/bits.h:23,
from include/linux/bitops.h:5,
from include/linux/kernel.h:12,
from include/linux/list.h:9,
from include/linux/wait.h:7,
from include/linux/wait_bit.h:8,
from include/linux/fs.h:6,
from include/linux/highmem.h:5,
from arch/x86/kvm/vmx/vmx.c:17:
include/linux/bitmap.h: In function 'bitmap_get_value':
>> include/linux/bits.h:26:28: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bitmap.h: In function 'bitmap_set_value':
>> include/linux/bits.h:26:28: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
In file included from arch/x86/kvm/vmx/vmx.c:50:
arch/x86/kvm/vmx/capabilities.h: At top level:
arch/x86/kvm/vmx/capabilities.h:7:10: fatal error: lapic.h: No such file or directory
7 | #include "lapic.h"
| ^~~~~~~~~
cc1: all warnings being treated as errors
compilation terminated.
--
In file included from include/linux/bits.h:23,
from include/linux/bitops.h:5,
from include/linux/kernel.h:12,
from include/linux/list.h:9,
from include/linux/preempt.h:11,
from include/linux/hardirq.h:5,
from include/linux/kvm_host.h:7,
from arch/x86/kvm/vmx/pmu_intel.c:12:
include/linux/bitmap.h: In function 'bitmap_get_value':
>> include/linux/bits.h:26:28: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:590:35: note: in expansion of macro 'GENMASK'
590 | return (map[index] >> offset) & GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bitmap.h: In function 'bitmap_set_value':
>> include/linux/bits.h:26:28: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
include/linux/bits.h:26:40: error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]
26 | __builtin_constant_p((l) > (h)), (l) > (h), 0)))
| ^
include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO'
16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); })))
| ^
include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK'
39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l))
| ^~~~~~~~~~~~~~~~~~~
include/linux/bitmap.h:630:11: note: in expansion of macro 'GENMASK'
630 | value &= GENMASK(nbits - 1, 0);
| ^~~~~~~
arch/x86/kvm/vmx/pmu_intel.c: At top level:
arch/x86/kvm/vmx/pmu_intel.c:15:10: fatal error: x86.h: No such file or directory
15 | #include "x86.h"
| ^~~~~~~
cc1: all warnings being treated as errors
compilation terminated.
..

vim +26 include/linux/bits.h

8bd9cb51daac89 Will Deacon 2018-06-19 15
8bd9cb51daac89 Will Deacon 2018-06-19 16 /*
8bd9cb51daac89 Will Deacon 2018-06-19 17 * Create a contiguous bitmask starting at bit position @l and ending at
8bd9cb51daac89 Will Deacon 2018-06-19 18 * position @h. For example
8bd9cb51daac89 Will Deacon 2018-06-19 19 * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
8bd9cb51daac89 Will Deacon 2018-06-19 20 */
295bcca84916cb Rikard Falkeborn 2020-04-06 21 #if !defined(__ASSEMBLY__) && \
295bcca84916cb Rikard Falkeborn 2020-04-06 22 (!defined(CONFIG_CC_IS_GCC) || CONFIG_GCC_VERSION >= 49000)
295bcca84916cb Rikard Falkeborn 2020-04-06 23 #include <linux/build_bug.h>
295bcca84916cb Rikard Falkeborn 2020-04-06 24 #define GENMASK_INPUT_CHECK(h, l) \
295bcca84916cb Rikard Falkeborn 2020-04-06 25 (BUILD_BUG_ON_ZERO(__builtin_choose_expr( \
295bcca84916cb Rikard Falkeborn 2020-04-06 @26 __builtin_constant_p((l) > (h)), (l) > (h), 0)))
295bcca84916cb Rikard Falkeborn 2020-04-06 27 #else
295bcca84916cb Rikard Falkeborn 2020-04-06 28 /*
295bcca84916cb Rikard Falkeborn 2020-04-06 29 * BUILD_BUG_ON_ZERO is not available in h files included from asm files,
295bcca84916cb Rikard Falkeborn 2020-04-06 30 * disable the input check if that is the case.
295bcca84916cb Rikard Falkeborn 2020-04-06 31 */
295bcca84916cb Rikard Falkeborn 2020-04-06 32 #define GENMASK_INPUT_CHECK(h, l) 0
295bcca84916cb Rikard Falkeborn 2020-04-06 33 #endif
295bcca84916cb Rikard Falkeborn 2020-04-06 34

:::::: The code at line 26 was first introduced by commit
:::::: 295bcca84916cb5079140a89fccb472bb8d1f6e2 linux/bits.h: add compile time sanity check of GENMASK inputs

:::::: TO: Rikard Falkeborn <[email protected]>
:::::: CC: Linus Torvalds <[email protected]>

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]

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2020-06-19 07:04:11

by Syed Nayyar Waris

[permalink] [raw]

Subject: Re: [PATCH v8 4/4] gpio: xilinx: Utilize for_each_set_clump macro

>
> Hi Syed,
>
> Thank you for the patch! Perhaps something to improve:
>
> [auto build test WARNING on 444fc5cde64330661bf59944c43844e7d4c2ccd8]
>
> url: https://github.com/0day-ci/linux/commits/Syed-Nayyar-Waris/Introduce-the-for_each_set_clump-macro/20200615-205729
> base: 444fc5cde64330661bf59944c43844e7d4c2ccd8
> config: sparc64-randconfig-s032-20200615 (attached as .config)
> compiler: sparc64-linux-gcc (GCC) 9.3.0
> reproduce:
> # apt-get install sparse
> # sparse version: v0.6.2-rc1-3-g55607964-dirty
> # save the attached .config to linux build tree
> make W=1 C=1 ARCH=sparc64 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'
>

>
>
> sparse warnings: (new ones prefixed by >>)
>
> >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> include/linux/bitmap.h:594:63: sparse: sparse: shift too big (64) for type unsigned long
> >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> >> include/linux/bitmap.h:638:17: sparse: sparse: invalid access past the end of 'old' (8 8)
>

Hi All,

It seems to me that to reproduce this warning, I have to use the
sparc64 compiler. I have installed 'sparc64-linux-gnu-gcc' on my
computer.
I have to specify that this compiler needs to be used for build
process. How/ Where do I specify this?

I have downloaded the config.gz (has config file) and placed it at the
root of the linux kernel project tree. But the Makefile STILL has
'gcc' as the compiler. When I build, it is the 'gcc' compiler being
used and not 'sparc64-linux-gnu-gcc'. I know I can manually change the
Makefile to use sparc64 compiler, but I think there must be some more
elegant way to do this, perhaps using make menuconfig?

Kindly illuminate as to how shall I reproduce the compiler warning.

Regards
Syed Nayyar Waris

> vim +639 include/linux/bitmap.h
>
> 169c474fb22d8a William Breathitt Gray 2019-12-04 613
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 614 /**
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 615 * bitmap_set_value - set n-bit value within a memory region
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 616 * @map: address to the bitmap memory region
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 617 * @value: value of nbits
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 618 * @start: bit offset of the n-bit value
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 619 * @nbits: size of value in bits
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 620 */
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 621 static inline void bitmap_set_value(unsigned long *map,
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 622 unsigned long value,
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 623 unsigned long start, unsigned long nbits)
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 624 {
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 625 const size_t index = BIT_WORD(start);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 626 const unsigned long offset = start % BITS_PER_LONG;
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 627 const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 628 const unsigned long space = ceiling - start;
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 629
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 630 value &= GENMASK(nbits - 1, 0);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 631
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 632 if (space >= nbits) {
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 633 map[index] &= ~(GENMASK(nbits + offset - 1, offset));
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 634 map[index] |= value << offset;
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 635 } else {
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 636 map[index] &= ~BITMAP_FIRST_WORD_MASK(start);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 637 map[index] |= value << offset;
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 @638 map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 @639 map[index + 1] |= (value >> space);
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 640 }
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 641 }
> 803024b6c8a375 Syed Nayyar Waris 2020-06-15 642
>
> :::::: The code at line 639 was first introduced by commit
> :::::: 803024b6c8a375ba9e9e9467595d7d52d4f6a38e bitops: Introduce the for_each_set_clump macro
>
> :::::: TO: Syed Nayyar Waris <[email protected]>

2020-06-19 08:44:02

by Andy Shevchenko

[permalink] [raw]

Subject: Re: [PATCH v8 4/4] gpio: xilinx: Utilize for_each_set_clump macro

On Fri, Jun 19, 2020 at 10:02 AM Syed Nayyar Waris <[email protected]> wrote:

...

> > config: sparc64-randconfig-s032-20200615 (attached as .config)
> > compiler: sparc64-linux-gcc (GCC) 9.3.0
> > reproduce:
> > # apt-get install sparse
> > # sparse version: v0.6.2-rc1-3-g55607964-dirty
> > # save the attached .config to linux build tree
> > make W=1 C=1 ARCH=sparc64 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

...

> > sparse warnings: (new ones prefixed by >>)
> >
> > >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> > >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> > include/linux/bitmap.h:594:63: sparse: sparse: shift too big (64) for type unsigned long
> > >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> > >> include/linux/bitmap.h:638:17: sparse: sparse: invalid access past the end of 'old' (8 8)

> It seems to me that to reproduce this warning, I have to use the
> sparc64 compiler. I have installed 'sparc64-linux-gnu-gcc' on my
> computer.

Sparse is not a compiler.

> I have to specify that this compiler needs to be used for build
> process. How/ Where do I specify this?
>
> I have downloaded the config.gz (has config file) and placed it at the
> root of the linux kernel project tree. But the Makefile STILL has
> 'gcc' as the compiler. When I build, it is the 'gcc' compiler being
> used and not 'sparc64-linux-gnu-gcc'. I know I can manually change the
> Makefile to use sparc64 compiler, but I think there must be some more
> elegant way to do this, perhaps using make menuconfig?

If you wish to run a compilation, download a compiler from [1], and,
after adding its bin/ folder to PATH, run
make CROSS_COMPILE=sparc64-linux- ARCH=sparc64 ... # first generate .config

> Kindly illuminate as to how shall I reproduce the compiler warning.

> > 803024b6c8a375 Syed Nayyar Waris 2020-06-15 @638 map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits);
> > 803024b6c8a375 Syed Nayyar Waris 2020-06-15 @639 map[index + 1] |= (value >> space);

Hmm... I think I sent a reply [2] where I explained how space can be
64. Do you agree with analysis?

[1]: https://mirrors.edge.kernel.org/pub/tools/crosstool/
[2]: https://lore.kernel.org/lkml/[email protected]/

--
With Best Regards,
Andy Shevchenko

2020-06-19 09:13:10

by Andy Shevchenko

[permalink] [raw]

Subject: Re: [PATCH v8 4/4] gpio: xilinx: Utilize for_each_set_clump macro

On Fri, Jun 19, 2020 at 11:38:59AM +0300, Andy Shevchenko wrote:
> On Fri, Jun 19, 2020 at 10:02 AM Syed Nayyar Waris <[email protected]> wrote:
>
> ...
>
> > > config: sparc64-randconfig-s032-20200615 (attached as .config)
> > > compiler: sparc64-linux-gcc (GCC) 9.3.0
> > > reproduce:
> > > # apt-get install sparse
> > > # sparse version: v0.6.2-rc1-3-g55607964-dirty
> > > # save the attached .config to linux build tree
> > > make W=1 C=1 ARCH=sparc64 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'
>
> ...
>
> > > sparse warnings: (new ones prefixed by >>)
> > >
> > > >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> > > >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> > > include/linux/bitmap.h:594:63: sparse: sparse: shift too big (64) for type unsigned long
> > > >> include/linux/bitmap.h:639:45: sparse: sparse: shift too big (64) for type unsigned long
> > > >> include/linux/bitmap.h:638:17: sparse: sparse: invalid access past the end of 'old' (8 8)
>
> > It seems to me that to reproduce this warning, I have to use the
> > sparc64 compiler. I have installed 'sparc64-linux-gnu-gcc' on my
> > computer.
>
> Sparse is not a compiler.

On x86_64:

CHECK drivers/gpio/gpio-xilinx.c
include/linux/bitmap.h:639:45: warning: shift too big (64) for type unsigned long
include/linux/bitmap.h:639:45: warning: shift too big (64) for type unsigned long
include/linux/bitmap.h:594:63: warning: shift too big (64) for type unsigned long
include/linux/bitmap.h:639:45: warning: shift too big (64) for type unsigned long
include/linux/bitmap.h:638:17: warning: invalid access past the end of 'old' (8 8)

> > I have to specify that this compiler needs to be used for build
> > process. How/ Where do I specify this?
> >
> > I have downloaded the config.gz (has config file) and placed it at the
> > root of the linux kernel project tree. But the Makefile STILL has
> > 'gcc' as the compiler. When I build, it is the 'gcc' compiler being
> > used and not 'sparc64-linux-gnu-gcc'. I know I can manually change the
> > Makefile to use sparc64 compiler, but I think there must be some more
> > elegant way to do this, perhaps using make menuconfig?
>
> If you wish to run a compilation, download a compiler from [1], and,
> after adding its bin/ folder to PATH, run
> make CROSS_COMPILE=sparc64-linux- ARCH=sparc64 ... # first generate .config
>
> > Kindly illuminate as to how shall I reproduce the compiler warning.
>
> > > 803024b6c8a375 Syed Nayyar Waris 2020-06-15 @638 map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits);
> > > 803024b6c8a375 Syed Nayyar Waris 2020-06-15 @639 map[index + 1] |= (value >> space);
>
> Hmm... I think I sent a reply [2] where I explained how space can be
> 64. Do you agree with analysis?
>
> [1]: https://mirrors.edge.kernel.org/pub/tools/crosstool/
> [2]: https://lore.kernel.org/lkml/[email protected]/

--
With Best Regards,
Andy Shevchenko

2020-06-19 14:29:08

by Luc Van Oostenryck

[permalink] [raw]

Subject: Re: [PATCH v8 4/4] gpio: xilinx: Utilize for_each_set_clump macro

On Tue, Jun 16, 2020 at 11:27:18AM +0530, Syed Nayyar Waris wrote:

Hi,

> Regarding the compilation warning reported above:
>
> "sparse: shift too big (64) for type unsigned long" at line 639
> "sparse: invalid access past the end of 'old' (8 8)" at line 638
>
> Kindly refer to the code above, at these line numbers.
>
> I am in the process of fixing this warning. But what would be the fix?
> ? At the moment can't think of a code-fix to make the compilation
> warning disappear (specially at line 639). Can anyone please explain
> to me the meaning of the compilation warning more deeply?

This error message is caused by sparse doing the check too early.
There is thus nothing to be fixed for it in this code.

Best regards,
-- Luc

2020-06-20 04:33:15

by Robin Murphy

[permalink] [raw]

Subject: Re: [PATCH v8 4/4] gpio: xilinx: Utilize for_each_set_clump macro

On 2020-06-15 13:54, Syed Nayyar Waris wrote:
> This patch reimplements the xgpio_set_multiple function in
> drivers/gpio/gpio-xilinx.c to use the new for_each_set_clump macro.
> Instead of looping for each bit in xgpio_set_multiple
> function, now we can check each channel at a time and save cycles.
>
> Cc: Bartosz Golaszewski <[email protected]>
> Cc: Michal Simek <[email protected]>
> Signed-off-by: Syed Nayyar Waris <[email protected]>
> Signed-off-by: William Breathitt Gray <[email protected]>
> ---
> Changes in v8:
> - No change.
>
> Changes in v7:
> - No change.
>
> Changes in v6:
> - No change.
>
> Changes in v5:
> - Minor change: Inline values '32' and '64' in code for better
> code readability.
>
> Changes in v4:
> - Minor change: Inline values '32' and '64' in code for better
> code readability.
>
> Changes in v3:
> - No change.
>
> Changes in v2:
> - No change.
>
> drivers/gpio/gpio-xilinx.c | 62 ++++++++++++++++++++------------------
> 1 file changed, 32 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpio/gpio-xilinx.c b/drivers/gpio/gpio-xilinx.c
> index 67f9f82e0db0..e81092dea27e 100644
> --- a/drivers/gpio/gpio-xilinx.c
> +++ b/drivers/gpio/gpio-xilinx.c
> @@ -136,39 +136,41 @@ static void xgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
> static void xgpio_set_multiple(struct gpio_chip *gc, unsigned long *mask,
> unsigned long *bits)
> {
> - unsigned long flags;
> + unsigned long flags[2];
> struct xgpio_instance *chip = gpiochip_get_data(gc);
> - int index = xgpio_index(chip, 0);
> - int offset, i;
> -
> - spin_lock_irqsave(&chip->gpio_lock[index], flags);
> -
> - /* Write to GPIO signals */
> - for (i = 0; i < gc->ngpio; i++) {
> - if (*mask == 0)
> - break;
> - /* Once finished with an index write it out to the register */
> - if (index != xgpio_index(chip, i)) {
> - xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
> - index * XGPIO_CHANNEL_OFFSET,
> - chip->gpio_state[index]);
> - spin_unlock_irqrestore(&chip->gpio_lock[index], flags);
> - index = xgpio_index(chip, i);
> - spin_lock_irqsave(&chip->gpio_lock[index], flags);
> - }
> - if (__test_and_clear_bit(i, mask)) {
> - offset = xgpio_offset(chip, i);
> - if (test_bit(i, bits))
> - chip->gpio_state[index] |= BIT(offset);
> - else
> - chip->gpio_state[index] &= ~BIT(offset);
> - }
> + u32 *const state = chip->gpio_state;
> + unsigned int *const width = chip->gpio_width;

Immutable pointers to mutable data are pretty unusual, especially for
temporary local variables. Let me share my thought process upon seeing this:

- hmm, is "* const" simply a mistake that's meant to be "const *"?
- <scan the rest of the function> no, updating chip->gpio_state seems
appropriate, so it can't be that.
- does anything take the address of either of these variables that might
justify it?
- <scan the rest of the function again> nope, they're only ever used by
value
- hmm, maybe it's just paranoia, but in that case why isn't width "const
* const" since chip->gpio_width shouldn't need to be modified?
- hmm...

And at that point I've spent nearly a minute parsing what should have
been be some trivial definitions of local shorthand variables. Defensive
programming is all very well, but the distraction to readers (I can't be
the only one) can easily outweigh any perceived value in trying to
harden against theoretical future developer error in a straightforward
~30-line function.

> + unsigned long offset, clump;
> + size_t index;
> +
> + DECLARE_BITMAP(old, 64);
> + DECLARE_BITMAP(new, 64);
> + DECLARE_BITMAP(changed, 64);
> +
> + spin_lock_irqsave(&chip->gpio_lock[0], flags[0]);
> + spin_lock_irqsave(&chip->gpio_lock[1], flags[1]);

Why _irqsave on the inner lock? (think about it...)

> +
> + bitmap_set_value(old, state[0], 0, width[0]);
> + bitmap_set_value(old, state[1], width[0], width[1]);
> + bitmap_replace(new, old, bits, mask, gc->ngpio);
> +
> + bitmap_set_value(old, state[0], 0, 32);
> + bitmap_set_value(old, state[1], 32, 32);
> + state[0] = bitmap_get_value(new, 0, width[0]);
> + state[1] = bitmap_get_value(new, width[0], width[1]);
> + bitmap_set_value(new, state[0], 0, 32);
> + bitmap_set_value(new, state[1], 32, 32);
> + bitmap_xor(changed, old, new, 64);
> +
> + for_each_set_clump(offset, clump, changed, 64, 32) {
> + index = offset / 32;
> + xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
> + index * XGPIO_CHANNEL_OFFSET,
> + state[index]);
> }

TBH this looks like a rather overcomplicated and horribly inefficient
way of doing:

if (((u32 *)changed)[0])
xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET,
state[0]);
if (((u32 *)changed)[1])
xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
XGPIO_CHANNEL_OFFSET, state[1]);

(and doing the changed/state update itself one word at a time for each
condition would probably be a fair bit more efficient in terms of
minimising spilling to the stack on 32-bit machines)

I can see this API having merit if the clumps are a weird size or
expected to be significantly sparse in the bitmap, but making
out-of-line calls to an iterator which itself involves another
out-of-line call and an integer division, all just to process two halves
of a 64-bit value, seems... unnecessarily silly :/

[drive-by review since I had a "packing small values into bitmaps"
use-case and wondered if there might be anything interesting here]

Robin.

>
> - xgpio_writereg(chip->regs + XGPIO_DATA_OFFSET +
> - index * XGPIO_CHANNEL_OFFSET, chip->gpio_state[index]);
> -
> - spin_unlock_irqrestore(&chip->gpio_lock[index], flags);
> + spin_unlock_irqrestore(&chip->gpio_lock[1], flags[1]);
> + spin_unlock_irqrestore(&chip->gpio_lock[0], flags[0]);
> }
>
> /**
>

2020-06-20 13:49:36

by Syed Nayyar Waris

[permalink] [raw]

Subject: Re: [PATCH v8 1/4] bitops: Introduce the for_each_set_clump macro

On Tue, Jun 16, 2020 at 1:44 PM Andy Shevchenko
<[email protected]> wrote:
>
> On Mon, Jun 15, 2020 at 06:21:18PM +0530, Syed Nayyar Waris wrote:
> > This macro iterates for each group of bits (clump) with set bits,
> > within a bitmap memory region. For each iteration, "start" is set to
> > the bit offset of the found clump, while the respective clump value is
> > stored to the location pointed by "clump". Additionally, the
> > bitmap_get_value and bitmap_set_value functions are introduced to
> > respectively get and set a value of n-bits in a bitmap memory region.
> > The n-bits can have any size less than or equal to BITS_PER_LONG.
> > Moreover, during setting value of n-bit in bitmap, if a situation arise
> > that the width of next n-bit is exceeding the word boundary, then it
> > will divide itself such that some portion of it is stored in that word,
> > while the remaining portion is stored in the next higher word. Similar
> > situation occurs while retrieving value of n-bits from bitmap.
>
> On the second view...
>
> > +static inline unsigned long bitmap_get_value(const unsigned long *map,
> > + unsigned long start,
> > + unsigned long nbits)
> > +{
> > + const size_t index = BIT_WORD(start);
> > + const unsigned long offset = start % BITS_PER_LONG;
>
> > + const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
>
> This perhaps should use round_up()

Hi Andy. I will see with round_up(). I will check and inform you.
Further below ...

>
> > + const unsigned long space = ceiling - start;
>
> And I think I see a scenario to complain.
>
> If start == 0, then ceiling will be 64.
> space == 64. Not good.

Yes, you are right, when the 'start' is '0', then 'space' will be 64
(on arch where BITS_PER_LONG is 64).
But actually I want this to happen. I need 'space' to hold value 64
when 'start' is '0'. The reason is as follows:

Taking the example of bitmap_set_value(). If the nbits is 16 (as
example) and 'start' is zero, The 'if' condition will be executed
inside bitmap_set_value() when 'start' is zero because space(64) >=
nbits(16) is true. This 'if' condition is for the case when nbits
falls completely into the first word and the nbits doesn't have to
divide itself into another higher word of the bitmap.

This is what I want to happen. I will think more about this and let
you know further.

Kindly let me know If I have misunderstood something. Thanks !

>
> > + unsigned long value_low, value_high;
> > +
> > + if (space >= nbits)
> > + return (map[index] >> offset) & GENMASK(nbits - 1, 0);
> > + else {
> > + value_low = map[index] & BITMAP_FIRST_WORD_MASK(start);
> > + value_high = map[index + 1] & BITMAP_LAST_WORD_MASK(start + nbits);
> > + return (value_low >> offset) | (value_high << space);
> > + }
> > +}
>
> ...
>
> > +/**
> > + * bitmap_set_value - set n-bit value within a memory region
> > + * @map: address to the bitmap memory region
> > + * @value: value of nbits
> > + * @start: bit offset of the n-bit value
> > + * @nbits: size of value in bits
> > + */
> > +static inline void bitmap_set_value(unsigned long *map,
> > + unsigned long value,
> > + unsigned long start, unsigned long nbits)
> > +{
> > + const size_t index = BIT_WORD(start);
> > + const unsigned long offset = start % BITS_PER_LONG;
>
> > + const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
> > + const unsigned long space = ceiling - start;
>
> Ditto for both lines.
>
> > + value &= GENMASK(nbits - 1, 0);
> > +
> > + if (space >= nbits) {
> > + map[index] &= ~(GENMASK(nbits + offset - 1, offset));
> > + map[index] |= value << offset;
> > + } else {
> > + map[index] &= ~BITMAP_FIRST_WORD_MASK(start);
> > + map[index] |= value << offset;
> > + map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits);
> > + map[index + 1] |= (value >> space);
> > + }
> > +}
>
> --
> With Best Regards,
> Andy Shevchenko
>
>

2020-06-20 23:45:45

by Syed Nayyar Waris

[permalink] [raw]

Subject: Re: [PATCH v8 1/4] bitops: Introduce the for_each_set_clump macro

On Tue, Jun 16, 2020 at 1:44 PM Andy Shevchenko
<[email protected]> wrote:
>
> On Mon, Jun 15, 2020 at 06:21:18PM +0530, Syed Nayyar Waris wrote:
> > This macro iterates for each group of bits (clump) with set bits,
> > within a bitmap memory region. For each iteration, "start" is set to
> > the bit offset of the found clump, while the respective clump value is
> > stored to the location pointed by "clump". Additionally, the
> > bitmap_get_value and bitmap_set_value functions are introduced to
> > respectively get and set a value of n-bits in a bitmap memory region.
> > The n-bits can have any size less than or equal to BITS_PER_LONG.
> > Moreover, during setting value of n-bit in bitmap, if a situation arise
> > that the width of next n-bit is exceeding the word boundary, then it
> > will divide itself such that some portion of it is stored in that word,
> > while the remaining portion is stored in the next higher word. Similar
> > situation occurs while retrieving value of n-bits from bitmap.
>
> On the second view...
>
> > +static inline unsigned long bitmap_get_value(const unsigned long *map,
> > + unsigned long start,
> > + unsigned long nbits)
> > +{
> > + const size_t index = BIT_WORD(start);
> > + const unsigned long offset = start % BITS_PER_LONG;
>
> > + const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
>
> This perhaps should use round_up()

I checked with 'round_up'. I am getting the same values as I was
getting with 'roundup'.
I have checked with different clump tests.
Moreover, wherever the 'space' was being evaluated as 64, in the case
of 'roundup', it is also getting evaluated to the same value (of 64),
in case of 'round_up' also.

Further below ...

>
> > + const unsigned long space = ceiling - start;
>
> And I think I see a scenario to complain.
>
> If start == 0, then ceiling will be 64.
> space == 64. Not good.

Yes, you are right, when the 'start' is '0', then 'space' will be 64
(on arch where BITS_PER_LONG is 64).
But actually I want this to happen. I need 'space' to hold value 64
when 'start' is '0'. The reason is as follows:

Taking the example of bitmap_set_value(). If the nbits is 16 (as
example) and 'start' is zero, The 'if' condition will be executed
inside bitmap_set_value() when 'start' is zero because space(64) >=
nbits(16) is true. This 'if' condition is for the case when nbits
falls completely into the first word and the nbits doesn't have to
divide itself into another higher word of the bitmap.

This is what should happen according to me. If space is less than 64,
lets say 63 or 62, then it will not correctly indicate the remaining
space for nbits to fill in (bitmap_set_value) or to extract from
(bitmap_get_value).

Kindly let me know If I have misunderstood something. Thanks !

>
> > + unsigned long value_low, value_high;
> > +
> > + if (space >= nbits)
> > + return (map[index] >> offset) & GENMASK(nbits - 1, 0);
> > + else {
> > + value_low = map[index] & BITMAP_FIRST_WORD_MASK(start);
> > + value_high = map[index + 1] & BITMAP_LAST_WORD_MASK(start + nbits);
> > + return (value_low >> offset) | (value_high << space);
> > + }
> > +}
>
> ...
>
> > +/**
> > + * bitmap_set_value - set n-bit value within a memory region
> > + * @map: address to the bitmap memory region
> > + * @value: value of nbits
> > + * @start: bit offset of the n-bit value
> > + * @nbits: size of value in bits
> > + */
> > +static inline void bitmap_set_value(unsigned long *map,
> > + unsigned long value,
> > + unsigned long start, unsigned long nbits)
> > +{
> > + const size_t index = BIT_WORD(start);
> > + const unsigned long offset = start % BITS_PER_LONG;
>
> > + const unsigned long ceiling = roundup(start + 1, BITS_PER_LONG);
> > + const unsigned long space = ceiling - start;
>
> Ditto for both lines.
>
> > + value &= GENMASK(nbits - 1, 0);
> > +
> > + if (space >= nbits) {
> > + map[index] &= ~(GENMASK(nbits + offset - 1, offset));
> > + map[index] |= value << offset;
> > + } else {
> > + map[index] &= ~BITMAP_FIRST_WORD_MASK(start);
> > + map[index] |= value << offset;
> > + map[index + 1] &= ~BITMAP_LAST_WORD_MASK(start + nbits);
> > + map[index + 1] |= (value >> space);
> > + }
> > +}
>
> --
> With Best Regards,
> Andy Shevchenko
>
>