Correct, disambiguate, and reformat documentation.
Signed-off-by: Don Mullis <[email protected]>
Cc: Akinobu Mita <[email protected]>
---
Documentation/fault-injection/failmodule.sh | 4 -
Documentation/fault-injection/fault-injection.txt | 70 +++++++++++-----------
2 files changed, 37 insertions(+), 37 deletions(-)
Index: linux-2.6.18/Documentation/fault-injection/failmodule.sh
===================================================================
--- linux-2.6.18.orig/Documentation/fault-injection/failmodule.sh
+++ linux-2.6.18/Documentation/fault-injection/failmodule.sh
@@ -26,6 +26,6 @@ fi
# Disable any fault injection
echo 0 > /debug/$1/stacktrace-depth
-echo `cat /sys/module/$2/sections/.text` > /debug/$1/address-start
-echo `cat /sys/module/$2/sections/.exit.text` > /debug/$1/address-end
+echo `cat /sys/module/$2/sections/.text` > /debug/$1/require-start
+echo `cat /sys/module/$2/sections/.exit.text` > /debug/$1/require-end
echo $STACKTRACE_DEPTH > /debug/$1/stacktrace-depth
Index: linux-2.6.18/Documentation/fault-injection/fault-injection.txt
===================================================================
--- linux-2.6.18.orig/Documentation/fault-injection/fault-injection.txt
+++ linux-2.6.18/Documentation/fault-injection/fault-injection.txt
@@ -17,7 +17,7 @@ o fail_page_alloc
o fail_make_request
- injects disk IO errors on permitted devices by
+ injects disk IO errors on devices permitted by setting
/sys/block/<device>/make-it-fail or
/sys/block/<device>/<partition>/make-it-fail. (generic_make_request())
@@ -29,16 +29,16 @@ o debugfs entries
fault-inject-debugfs kernel module provides some debugfs entries for runtime
configuration of fault-injection capabilities.
-- /debug/*/probability:
+- /debug/fail*/probability:
likelihood of failure injection, in percent.
Format: <percent>
- Note that one-failure-per-handred is a very high error rate
- for some testcases. Please set probably=100 and configure
- /debug/*/interval for such testcases.
+ Note that one-failure-per-hundred is a very high error rate
+ for some testcases. Consider setting probability=100 and configure
+ /debug/fail*/interval for such testcases.
-- /debug/*/interval:
+- /debug/fail*/interval:
specifies the interval between failures, for calls to
should_fail() that pass all the other tests.
@@ -46,37 +46,36 @@ configuration of fault-injection capabil
Note that if you enable this, by setting interval>1, you will
probably want to set probability=100.
-- /debug/*/times:
+- /debug/fail*/times:
specifies how many times failures may happen at most.
A value of -1 means "no limit".
-- /debug/*/space:
+- /debug/fail*/space:
specifies an initial resource "budget", decremented by "size"
on each call to should_fail(,size). Failure injection is
suppressed until "space" reaches zero.
-- /debug/*/verbose
+- /debug/fail*/verbose
Format: { 0 | 1 | 2 }
- specifies the verbosity of the messages when failure is injected.
- We default to 0 (no extra messages), setting it to '1' will
- print only to tell failure happened, '2' will print call trace too -
- it is useful to debug the problems revealed by fault injection
- capabilities.
+ specifies the verbosity of the messages when failure is
+ injected. '0' means no messages; '1' will print only a single
+ log line per failure; '2' will print a call trace too -- useful
+ to debug the problems revealed by fault injection.
-- /debug/*/task-filter:
+- /debug/fail*/task-filter:
- Format: { 0 | 1 }
- A value of '0' disables filtering by process (default).
+ Format: { 'Y' | 'N' }
+ A value of 'N' disables filtering by process (default).
Any positive value limits failures to only processes indicated by
/proc/<pid>/make-it-fail==1.
-- /debug/*/require-start:
-- /debug/*/require-end:
-- /debug/*/reject-start:
-- /debug/*/reject-end:
+- /debug/fail*/require-start:
+- /debug/fail*/require-end:
+- /debug/fail*/reject-start:
+- /debug/fail*/reject-end:
specifies the range of virtual addresses tested during
stacktrace walking. Failure is injected only if some caller
@@ -85,22 +84,23 @@ configuration of fault-injection capabil
Default required range is [0,ULONG_MAX) (whole of virtual address space).
Default rejected range is [0,0).
-- /debug/*/stacktrace-depth:
+- /debug/fail*/stacktrace-depth:
specifies the maximum stacktrace depth walked during search
- for a caller within [address-start,address-end).
+ for a caller within [require-start,require-end) OR
+ [reject-start,reject-end).
- /debug/fail_page_alloc/ignore-gfp-highmem:
- Format: { 0 | 1 }
- default is 0, setting it to '1' won't inject failures into
+ Format: { 'Y' | 'N' }
+ default is 'N', setting it to 'Y' won't inject failures into
highmem/user allocations.
- /debug/failslab/ignore-gfp-wait:
- /debug/fail_page_alloc/ignore-gfp-wait:
- Format: { 0 | 1 }
- default is 0, setting it to '1' will inject failures
+ Format: { 'Y' | 'N' }
+ default is 'N', setting it to 'Y' will inject failures
only into non-sleep allocations (GFP_ATOMIC allocations).
o Boot option
@@ -124,22 +124,22 @@ o define the fault attributes
Please see the definition of struct fault_attr in fault-inject.h
for details.
-o provide the way to configure fault attributes
+o provide a way to configure fault attributes
- boot option
If you need to enable the fault injection capability from boot time, you can
- provide boot option to configure it. There is a helper function for it.
+ provide boot option to configure it. There is a helper function for it:
- setup_fault_attr(attr, str);
+ setup_fault_attr(attr, str);
- debugfs entries
failslab, fail_page_alloc, and fail_make_request use this way.
- There is a helper function for it.
+ Helper functions:
- init_fault_attr_entries(entries, attr, name);
- void cleanup_fault_attr_entries(entries);
+ init_fault_attr_entries(entries, attr, name);
+ void cleanup_fault_attr_entries(entries);
- module parameters
@@ -149,9 +149,9 @@ o provide the way to configure fault att
o add a hook to insert failures
- should_fail() returns 1 when failures should happen.
+ Upon should_fail() returning true, client code should inject a failure.
- should_fail(attr,size);
+ should_fail(attr, size);
Application Examples
--------------------
Use bool-true-false throughout.
Signed-off-by: Don Mullis <[email protected]>
Cc: Akinobu Mita <[email protected]>
---
include/linux/fault-inject.h | 2 +-
lib/fault-inject.c | 40 +++++++++++++++++++---------------------
2 files changed, 20 insertions(+), 22 deletions(-)
Index: linux-2.6.18/include/linux/fault-inject.h
===================================================================
--- linux-2.6.18.orig/include/linux/fault-inject.h
+++ linux-2.6.18/include/linux/fault-inject.h
@@ -57,7 +57,7 @@ struct fault_attr {
#define DECLARE_FAULT_ATTR(name) struct fault_attr name = FAULT_ATTR_INITIALIZER
int setup_fault_attr(struct fault_attr *attr, char *str);
void should_fail_srandom(unsigned long entropy);
-int should_fail(struct fault_attr *attr, ssize_t size);
+bool should_fail(struct fault_attr *attr, ssize_t size);
#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
Index: linux-2.6.18/lib/fault-inject.c
===================================================================
--- linux-2.6.18.orig/lib/fault-inject.c
+++ linux-2.6.18/lib/fault-inject.c
@@ -48,7 +48,7 @@ static void fail_dump(struct fault_attr
#define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
-static int fail_task(struct fault_attr *attr, struct task_struct *task)
+static bool fail_task(struct fault_attr *attr, struct task_struct *task)
{
return !in_interrupt() && task->make_it_fail;
}
@@ -68,15 +68,15 @@ static asmlinkage int fail_stacktrace_ca
break;
if (attr->reject_start <= UNW_PC(info) &&
UNW_PC(info) < attr->reject_end)
- return 0;
+ return false;
if (attr->require_start <= UNW_PC(info) &&
UNW_PC(info) < attr->require_end)
- found = 1;
+ found = true;
}
return found;
}
-static int fail_stacktrace(struct fault_attr *attr)
+static bool fail_stacktrace(struct fault_attr *attr)
{
struct unwind_frame_info info;
@@ -85,9 +85,7 @@ static int fail_stacktrace(struct fault_
#elif defined(CONFIG_STACKTRACE)
-#define MAX_STACK_TRACE_DEPTH 32
-
-static int fail_stacktrace(struct fault_attr *attr)
+static bool fail_stacktrace(struct fault_attr *attr)
{
struct stack_trace trace;
int depth = attr->stacktrace_depth;
@@ -109,26 +107,26 @@ static int fail_stacktrace(struct fault_
for (n = 0; n < trace.nr_entries; n++) {
if (attr->reject_start <= entries[n] &&
entries[n] < attr->reject_end)
- return 0;
+ return false;
if (attr->require_start <= entries[n] &&
entries[n] < attr->require_end)
- found = 1;
+ found = true;
}
return found;
}
#else
-static inline int fail_stacktrace(struct fault_attr *attr)
+static inline bool fail_stacktrace(struct fault_attr *attr)
{
- static int firsttime = 1;
+ static bool firsttime = true;
if (firsttime) {
printk(KERN_WARNING
"This architecture does not implement save_stack_trace()\n");
- firsttime = 0;
+ firsttime = false;
}
- return 0;
+ return false;
}
#endif
@@ -138,32 +136,32 @@ static inline int fail_stacktrace(struct
* http://www.nongnu.org/failmalloc/
*/
-int should_fail(struct fault_attr *attr, ssize_t size)
+bool should_fail(struct fault_attr *attr, ssize_t size)
{
if (attr->task_filter && !fail_task(attr, current))
- return 0;
+ return false;
if (!fail_stacktrace(attr))
- return 0;
+ return false;
if (atomic_read(&attr->times) == 0)
- return 0;
+ return false;
if (atomic_read(&attr->space) > size) {
atomic_sub(size, &attr->space);
- return 0;
+ return false;
}
if (attr->interval > 1) {
attr->count++;
if (attr->count % attr->interval)
- return 0;
+ return false;
}
if (attr->probability > random32() % 100)
goto fail;
- return 0;
+ return false;
fail:
fail_dump(attr);
@@ -171,7 +169,7 @@ fail:
if (atomic_read(&attr->times) != -1)
atomic_dec_not_zero(&attr->times);
- return 1;
+ return true;
}
#ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
Clamp /debug/fail*/stacktrace-depth to MAX_STACK_TRACE_DEPTH.
Ensures that a read of /debug/fail*/stacktrace-depth always
returns a truthful answer.
Signed-off-by: Don Mullis <[email protected]>
Cc: Akinobu Mita <[email protected]>
---
lib/fault-inject.c | 27 +++++++++++++++++++++++----
1 file changed, 23 insertions(+), 4 deletions(-)
Index: linux-2.6.18/lib/fault-inject.c
===================================================================
--- linux-2.6.18.orig/lib/fault-inject.c
+++ linux-2.6.18/lib/fault-inject.c
@@ -53,6 +53,8 @@ static bool fail_task(struct fault_attr
return !in_interrupt() && task->make_it_fail;
}
+#define MAX_STACK_TRACE_DEPTH 32
+
#ifdef CONFIG_STACK_UNWIND
static asmlinkage int fail_stacktrace_callback(struct unwind_frame_info *info,
@@ -98,8 +100,7 @@ static bool fail_stacktrace(struct fault
trace.nr_entries = 0;
trace.entries = entries;
- trace.max_entries = (depth < MAX_STACK_TRACE_DEPTH) ?
- depth : MAX_STACK_TRACE_DEPTH;
+ trace.max_entries = depth;
trace.skip = 1;
trace.all_contexts = 0;
@@ -179,6 +180,13 @@ static void debugfs_ul_set(void *data, u
*(unsigned long *)data = val;
}
+static void debugfs_ul_set_MAX_STACK_TRACE_DEPTH(void *data, u64 val)
+{
+ *(unsigned long *)data =
+ val < MAX_STACK_TRACE_DEPTH ?
+ val : MAX_STACK_TRACE_DEPTH;
+}
+
static u64 debugfs_ul_get(void *data)
{
return *(unsigned long *)data;
@@ -192,6 +200,17 @@ static struct dentry *debugfs_create_ul(
return debugfs_create_file(name, mode, parent, value, &fops_ul);
}
+DEFINE_SIMPLE_ATTRIBUTE(fops_ul_MAX_STACK_TRACE_DEPTH, debugfs_ul_get,
+ debugfs_ul_set_MAX_STACK_TRACE_DEPTH, "%llu\n");
+
+static struct dentry *debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
+ const char *name, mode_t mode,
+ struct dentry *parent, unsigned long *value)
+{
+ return debugfs_create_file(name, mode, parent, value,
+ &fops_ul_MAX_STACK_TRACE_DEPTH);
+}
+
static void debugfs_atomic_t_set(void *data, u64 val)
{
atomic_set((atomic_t *)data, val);
@@ -284,8 +303,8 @@ int init_fault_attr_dentries(struct faul
mode, dir, &attr->task_filter);
attr->dentries.stacktrace_depth_file =
- debugfs_create_ul("stacktrace-depth", mode, dir,
- &attr->stacktrace_depth);
+ debugfs_create_ul_MAX_STACK_TRACE_DEPTH(
+ "stacktrace-depth", mode, dir, &attr->stacktrace_depth);
attr->dentries.require_start_file =
debugfs_create_ul("require-start", mode, dir, &attr->require_start);
Trivial optimization and simplification of should_fail().
Do cheaper disqualification tests first (performance gain not quantified).
Simplify logic; eliminate goto.
Signed-off-by: Don Mullis <[email protected]>
Cc: Akinobu Mita <[email protected]>
---
lib/fault-inject.c | 11 ++++-------
1 file changed, 4 insertions(+), 7 deletions(-)
Index: linux-2.6.18/lib/fault-inject.c
===================================================================
--- linux-2.6.18.orig/lib/fault-inject.c
+++ linux-2.6.18/lib/fault-inject.c
@@ -142,9 +142,6 @@ bool should_fail(struct fault_attr *attr
if (attr->task_filter && !fail_task(attr, current))
return false;
- if (!fail_stacktrace(attr))
- return false;
-
if (atomic_read(&attr->times) == 0)
return false;
@@ -159,12 +156,12 @@ bool should_fail(struct fault_attr *attr
return false;
}
- if (attr->probability > random32() % 100)
- goto fail;
+ if (attr->probability <= random32() % 100)
+ return false;
- return false;
+ if (!fail_stacktrace(attr))
+ return false;
-fail:
fail_dump(attr);
if (atomic_read(&attr->times) != -1)
Assign defaults most likely to please a new user:
1) generate some logging output
(verbose=2)
2) avoid injecting failures likely to lock up UI
(ignore_gfp_wait=1, ignore_gfp_highmem=1)
Signed-off-by: Don Mullis <[email protected]>
Cc: Akinobu Mita <[email protected]>
---
include/linux/fault-inject.h | 1 +
mm/page_alloc.c | 2 ++
mm/slab.c | 1 +
3 files changed, 4 insertions(+)
Index: linux-2.6.18/include/linux/fault-inject.h
===================================================================
--- linux-2.6.18.orig/include/linux/fault-inject.h
+++ linux-2.6.18/include/linux/fault-inject.h
@@ -52,6 +52,7 @@ struct fault_attr {
.times = ATOMIC_INIT(1), \
.require_end = ULONG_MAX, \
.stacktrace_depth = 32, \
+ .verbose = 2, \
}
#define DECLARE_FAULT_ATTR(name) struct fault_attr name = FAULT_ATTR_INITIALIZER
Index: linux-2.6.18/mm/page_alloc.c
===================================================================
--- linux-2.6.18.orig/mm/page_alloc.c
+++ linux-2.6.18/mm/page_alloc.c
@@ -914,6 +914,8 @@ static struct fail_page_alloc_attr {
} fail_page_alloc = {
.attr = FAULT_ATTR_INITIALIZER,
+ .ignore_gfp_wait = 1,
+ .ignore_gfp_highmem = 1,
};
static int __init setup_fail_page_alloc(char *str)
Index: linux-2.6.18/mm/slab.c
===================================================================
--- linux-2.6.18.orig/mm/slab.c
+++ linux-2.6.18/mm/slab.c
@@ -3108,6 +3108,7 @@ static struct failslab_attr {
} failslab = {
.attr = FAULT_ATTR_INITIALIZER,
+ .ignore_gfp_wait = 1,
};
static int __init setup_failslab(char *str)