[PATCH 1/5 -mm] fault-injection: Correct, disambiguate, and reformat documentation.

[PATCH 1/5 -mm] fault-injection: Correct, disambiguate, and reformat documentation.

[Don Mullis]

Correct, disambiguate, and reformat documentation.

Signed-off-by: Don Mullis <dwm@meer.net>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
---
 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
 --------------------

[PATCH 2/5 -mm] fault-injection: Use bool-true-false throughout

[Don Mullis]

Use bool-true-false throughout.

Signed-off-by: Don Mullis <dwm@meer.net>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
---
 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

[PATCH 3/5 -mm] fault-injection: Clamp debugfs stacktrace-depth to MAX_STACK_TRACE_DEPTH

[Don Mullis]

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 <dwm@meer.net>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
---
 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);

[PATCH 4/5 -mm] fault-injection: optimize and simplify should_fail()

[Don Mullis]

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 <dwm@meer.net>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
---
 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)

[PATCH 5/5 -mm] fault-injection: defaults likely to please a new user

[Don Mullis]

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 <dwm@meer.net>
Cc: Akinobu Mita <akinobu.mita@gmail.com>
---
 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)