From: Petr Tesarik <[email protected]>
Add some kernel-doc comments and move the existing documentation of struct
io_tlb_slot to its correct location. The latter was forgotten in commit
942a8186eb445 ("swiotlb: move struct io_tlb_slot to swiotlb.c").
Use the opportunity to give swiotlb_do_find_slots() a more descriptive
name, which makes it clear how it differs from swiotlb_find_slots().
Signed-off-by: Petr Tesarik <[email protected]>
---
include/linux/swiotlb.h | 15 +++++++---
kernel/dma/swiotlb.c | 61 +++++++++++++++++++++++++++++++++++++----
2 files changed, 66 insertions(+), 10 deletions(-)
diff --git a/include/linux/swiotlb.h b/include/linux/swiotlb.h
index 07216af59e93..39313c3a791a 100644
--- a/include/linux/swiotlb.h
+++ b/include/linux/swiotlb.h
@@ -76,10 +76,6 @@ dma_addr_t swiotlb_map(struct device *dev, phys_addr_t phys,
* @nslabs: The number of IO TLB blocks (in groups of 64) between @start and
* @end. For default swiotlb, this is command line adjustable via
* setup_io_tlb_npages.
- * @list: The free list describing the number of free entries available
- * from each index.
- * @orig_addr: The original address corresponding to a mapped entry.
- * @alloc_size: Size of the allocated buffer.
* @debugfs: The dentry to debugfs.
* @late_alloc: %true if allocated using the page allocator
* @force_bounce: %true if swiotlb bouncing is forced
@@ -111,6 +107,17 @@ struct io_tlb_mem {
#endif
};
+/**
+ * is_swiotlb_buffer() - check if a physical address belongs to a swiotlb
+ * @dev: Device which has mapped the buffer.
+ * @paddr: Physical address within the DMA buffer.
+ *
+ * Check if @paddr points into a bounce buffer.
+ *
+ * Return:
+ * * %true if @paddr points into a bounce buffer
+ * * %false otherwise
+ */
static inline bool is_swiotlb_buffer(struct device *dev, phys_addr_t paddr)
{
struct io_tlb_mem *mem = dev->dma_io_tlb_mem;
diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
index 873b077d7e37..01161d040639 100644
--- a/kernel/dma/swiotlb.c
+++ b/kernel/dma/swiotlb.c
@@ -62,6 +62,13 @@
#define INVALID_PHYS_ADDR (~(phys_addr_t)0)
+/**
+ * struct io_tlb_slot - IO TLB slot descriptor
+ * @orig_addr: The original address corresponding to a mapped entry.
+ * @alloc_size: Size of the allocated buffer.
+ * @list: The free list describing the number of free entries available
+ * from each index.
+ */
struct io_tlb_slot {
phys_addr_t orig_addr;
size_t alloc_size;
@@ -632,11 +639,22 @@ static void dec_used(struct io_tlb_mem *mem, unsigned int nslots)
}
#endif /* CONFIG_DEBUG_FS */
-/*
- * Find a suitable number of IO TLB entries size that will fit this request and
- * allocate a buffer from that IO TLB pool.
+/**
+ * area_find_slots() - search for slots in one IO TLB memory area
+ * @dev: Device which maps the buffer.
+ * @area_index: Index of the IO TLB memory area to be searched.
+ * @orig_addr: Original (non-bounced) IO buffer address.
+ * @alloc_size: Total requested size of the bounce buffer,
+ * including initial alignment padding.
+ * @alloc_align_mask: Required alignment of the allocated buffer.
+ *
+ * Find a suitable sequence of IO TLB entries for the request and allocate
+ * a buffer from the given IO TLB memory area.
+ * This function takes care of locking.
+ *
+ * Return: Index of the first allocated slot, or -1 on error.
*/
-static int swiotlb_do_find_slots(struct device *dev, int area_index,
+static int area_find_slots(struct device *dev, int area_index,
phys_addr_t orig_addr, size_t alloc_size,
unsigned int alloc_align_mask)
{
@@ -731,6 +749,19 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index,
return slot_index;
}
+/**
+ * swiotlb_find_slots() - search for slots in the whole swiotlb
+ * @dev: Device which maps the buffer.
+ * @orig_addr: Original (non-bounced) IO buffer address.
+ * @alloc_size: Total requested size of the bounce buffer,
+ * including initial alignment padding.
+ * @alloc_align_mask: Required alignment of the allocated buffer.
+ *
+ * Search through the whole software IO TLB to find a sequence of slots that
+ * match the allocation constraints.
+ *
+ * Return: Index of the first allocated slot, or -1 on error.
+ */
static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
size_t alloc_size, unsigned int alloc_align_mask)
{
@@ -739,8 +770,8 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
int i = start, index;
do {
- index = swiotlb_do_find_slots(dev, i, orig_addr, alloc_size,
- alloc_align_mask);
+ index = area_find_slots(dev, i, orig_addr, alloc_size,
+ alloc_align_mask);
if (index >= 0)
return index;
if (++i >= mem->nareas)
@@ -752,6 +783,15 @@ static int swiotlb_find_slots(struct device *dev, phys_addr_t orig_addr,
#ifdef CONFIG_DEBUG_FS
+/**
+ * mem_used() - get number of used slots in an allocator
+ * @mem: Software IO TLB allocator.
+ *
+ * The result is accurate in this version of the function, because an atomic
+ * counter is available if CONFIG_DEBUG_FS is set.
+ *
+ * Return: Number of used slots.
+ */
static unsigned long mem_used(struct io_tlb_mem *mem)
{
return atomic_long_read(&mem->total_used);
@@ -759,6 +799,15 @@ static unsigned long mem_used(struct io_tlb_mem *mem)
#else /* !CONFIG_DEBUG_FS */
+/**
+ * mem_used() - get number of used slots in an allocator
+ * @mem: Software IO TLB allocator.
+ *
+ * The result is not accurate, because there is no locking of individual
+ * areas.
+ *
+ * Return: Approximate number of used slots.
+ */
static unsigned long mem_used(struct io_tlb_mem *mem)
{
int i;
--
2.25.1
On Thu, Jul 13, 2023 at 05:23:13PM +0200, Petr Tesarik wrote:
> From: Petr Tesarik <[email protected]>
>
> Add some kernel-doc comments and move the existing documentation of struct
> io_tlb_slot to its correct location. The latter was forgotten in commit
> 942a8186eb445 ("swiotlb: move struct io_tlb_slot to swiotlb.c").
>
> Use the opportunity to give swiotlb_do_find_slots() a more descriptive
> name, which makes it clear how it differs from swiotlb_find_slots().
Please keep the swiotlb_ prefix. Otherwise this looks good to me.
On Thu, Jul 20, 2023 at 09:56:09AM +0200, Petr Tesařík wrote:
> On Thu, 20 Jul 2023 08:38:19 +0200
> Christoph Hellwig <[email protected]> wrote:
>
> > On Thu, Jul 13, 2023 at 05:23:13PM +0200, Petr Tesarik wrote:
> > > From: Petr Tesarik <[email protected]>
> > >
> > > Add some kernel-doc comments and move the existing documentation of struct
> > > io_tlb_slot to its correct location. The latter was forgotten in commit
> > > 942a8186eb445 ("swiotlb: move struct io_tlb_slot to swiotlb.c").
> > >
> > > Use the opportunity to give swiotlb_do_find_slots() a more descriptive
> > > name, which makes it clear how it differs from swiotlb_find_slots().
> >
> > Please keep the swiotlb_ prefix. Otherwise this looks good to me.
>
> Will do. Out of curiosity, why does it matter for a static (file-local)
> function?
Because it makes looking at stack traces much easier.
On Thu, 20 Jul 2023 10:01:10 +0200
Christoph Hellwig <[email protected]> wrote:
> On Thu, Jul 20, 2023 at 09:56:09AM +0200, Petr Tesařík wrote:
> > On Thu, 20 Jul 2023 08:38:19 +0200
> > Christoph Hellwig <[email protected]> wrote:
> >
> > > On Thu, Jul 13, 2023 at 05:23:13PM +0200, Petr Tesarik wrote:
> > > > From: Petr Tesarik <[email protected]>
> > > >
> > > > Add some kernel-doc comments and move the existing documentation of struct
> > > > io_tlb_slot to its correct location. The latter was forgotten in commit
> > > > 942a8186eb445 ("swiotlb: move struct io_tlb_slot to swiotlb.c").
> > > >
> > > > Use the opportunity to give swiotlb_do_find_slots() a more descriptive
> > > > name, which makes it clear how it differs from swiotlb_find_slots().
> > >
> > > Please keep the swiotlb_ prefix. Otherwise this looks good to me.
> >
> > Will do. Out of curiosity, why does it matter for a static (file-local)
> > function?
>
> Because it makes looking at stack traces much easier.
Got it. Thanks!
Petr T
On Thu, 20 Jul 2023 08:38:19 +0200
Christoph Hellwig <[email protected]> wrote:
> On Thu, Jul 13, 2023 at 05:23:13PM +0200, Petr Tesarik wrote:
> > From: Petr Tesarik <[email protected]>
> >
> > Add some kernel-doc comments and move the existing documentation of struct
> > io_tlb_slot to its correct location. The latter was forgotten in commit
> > 942a8186eb445 ("swiotlb: move struct io_tlb_slot to swiotlb.c").
> >
> > Use the opportunity to give swiotlb_do_find_slots() a more descriptive
> > name, which makes it clear how it differs from swiotlb_find_slots().
>
> Please keep the swiotlb_ prefix. Otherwise this looks good to me.
Will do. Out of curiosity, why does it matter for a static (file-local)
function?
Petr T