This patch provides some functions for implement fault-injection
capabilities.
- Lightweight random simulator is taken from crasher module for SUSE kernel
- The function should_fail() is taken from failmalloc-1.0
(http://www.nongnu.org/failmalloc/)
Cc: [email protected]
Signed-off-by: Akinobu Mita <[email protected]>
include/linux/fault-inject.h | 41 ++++++++++++++++++++
lib/Kconfig.debug | 4 ++
lib/Makefile | 1
lib/fault-inject.c | 84 +++++++++++++++++++++++++++++++++++++++++++
4 files changed, 130 insertions(+)
Index: work-shouldfail/lib/Kconfig.debug
===================================================================
--- work-shouldfail.orig/lib/Kconfig.debug
+++ work-shouldfail/lib/Kconfig.debug
@@ -368,3 +368,7 @@ config RCU_TORTURE_TEST
at boot time (you probably don't).
Say M if you want the RCU torture tests to build as a module.
Say N if you are unsure.
+
+config FAULT_INJECTION
+ bool
+
Index: work-shouldfail/lib/Makefile
===================================================================
--- work-shouldfail.orig/lib/Makefile
+++ work-shouldfail/lib/Makefile
@@ -52,6 +52,7 @@ obj-$(CONFIG_SMP) += percpu_counter.o
obj-$(CONFIG_AUDIT_GENERIC) += audit.o
obj-$(CONFIG_SWIOTLB) += swiotlb.o
+obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o
hostprogs-y := gen_crc32table
clean-files := crc32table.h
Index: work-shouldfail/include/linux/fault-inject.h
===================================================================
--- /dev/null
+++ work-shouldfail/include/linux/fault-inject.h
@@ -0,0 +1,41 @@
+#ifndef _LINUX_FAULT_INJECT_H
+#define _LINUX_FAULT_INJECT_H
+
+#ifdef CONFIG_FAULT_INJECTION
+
+#include <linux/types.h>
+#include <asm/atomic.h>
+
+struct fault_attr {
+
+ /* how often it should fail in percent. */
+ unsigned long probability;
+
+ /* the interval of failures. */
+ unsigned long interval;
+
+ /*
+ * how many times failures may happen at most.
+ * A value of '-1' means infinity.
+ */
+ atomic_t times;
+
+ /*
+ * the size of free space where memory can be allocated safely.
+ * A value of '0' means infinity.
+ */
+ atomic_t space;
+
+ unsigned long count;
+};
+
+#define DEFINE_FAULT_ATTR(name) \
+ struct fault_attr name = { .times = ATOMIC_INIT(-1), }
+
+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);
+
+#endif /* CONFIG_FAULT_INJECTION */
+
+#endif /* _LINUX_FAULT_INJECT_H */
Index: work-shouldfail/lib/fault-inject.c
===================================================================
--- /dev/null
+++ work-shouldfail/lib/fault-inject.c
@@ -0,0 +1,84 @@
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/random.h>
+#include <linux/stat.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/module.h>
+#include <linux/fault-inject.h>
+
+int setup_fault_attr(struct fault_attr *attr, char *str)
+{
+ unsigned long probability;
+ unsigned long interval;
+ int times;
+ int space;
+
+ /* "<interval>,<probability>,<space>,<times>" */
+ if (sscanf(str, "%lu,%lu,%d,%d",
+ &interval, &probability, &space, ×) < 4) {
+ printk(KERN_WARNING "SHOULD_FAIL: failed to parse arguments\n");
+ return 0;
+ }
+
+ attr->probability = probability;
+ attr->interval = interval;
+ atomic_set(&attr->times, times);
+ atomic_set(&attr->space, space);
+
+ return 1;
+}
+
+#define failure_probability(attr) (attr)->probability
+#define failure_interval(attr) (attr)->interval
+#define max_failures(attr) (attr)->times
+#define current_space(attr) (attr)->space
+#define atomic_dec_not_zero(v) atomic_add_unless((v), -1, 0)
+
+static unsigned long rand_seed = 152L;
+
+static unsigned long should_fail_random(void)
+{
+ rand_seed = rand_seed * 690690L+1;
+ return rand_seed ^ jiffies;
+}
+
+void should_fail_srandom(unsigned long entropy)
+{
+ rand_seed ^= entropy;
+ should_fail_random();
+}
+
+/*
+ * This code is stolen from failmalloc-1.0
+ * http://www.nongnu.org/failmalloc/
+ */
+
+int should_fail(struct fault_attr *attr, ssize_t size)
+{
+ if (atomic_read(&max_failures(attr)) == 0)
+ return 0;
+
+ if (atomic_read(¤t_space(attr)) > size) {
+ atomic_sub(size, ¤t_space(attr));
+ return 0;
+ }
+
+ if (failure_interval(attr) > 1) {
+ attr->count++;
+ if (attr->count % failure_interval(attr))
+ return 0;
+ }
+
+ if (failure_probability(attr) > should_fail_random() % 100)
+ goto fail;
+
+ return 0;
+
+fail:
+
+ if (atomic_read(&max_failures(attr)) != -1)
+ atomic_dec_not_zero(&max_failures(attr));
+
+ return 1;
+}
--
Replace individual structure element comments with reference
to Documentation/fault-injection/fault-injection.txt
Init "interval" to 1 (smallest useful value).
Init "times" to 1 rather than -1 (infinity), for fewer
accidental system lockups.
Signed-off-by: Don Mullis <[email protected]>
---
include/linux/fault-inject.h | 20 +++++---------------
1 file changed, 5 insertions(+), 15 deletions(-)
Index: linux-2.6.17/include/linux/fault-inject.h
===================================================================
--- linux-2.6.17.orig/include/linux/fault-inject.h
+++ linux-2.6.17/include/linux/fault-inject.h
@@ -6,31 +6,21 @@
#include <linux/types.h>
#include <asm/atomic.h>
+/*
+ * For explanation of the elements of this struct, see
+ * Documentation/fault-injection/fault-injection.txt
+ */
struct fault_attr {
-
- /* how often it should fail in percent. */
unsigned long probability;
-
- /* the interval of failures. */
unsigned long interval;
-
- /*
- * how many times failures may happen at most.
- * A value of '-1' means infinity.
- */
atomic_t times;
-
- /*
- * the size of free space where memory can be allocated safely.
- * A value of '0' means infinity.
- */
atomic_t space;
unsigned long count;
};
#define DEFINE_FAULT_ATTR(name) \
- struct fault_attr name = { .times = ATOMIC_INIT(-1), }
+ struct fault_attr name = { .interval=1, .times = ATOMIC_INIT(1), }
int setup_fault_attr(struct fault_attr *attr, char *str);
void should_fail_srandom(unsigned long entropy);
On Mon, Sep 18, 2006 at 10:50:54PM -0700, Don Mullis wrote:
> Replace individual structure element comments with reference
> to Documentation/fault-injection/fault-injection.txt
>
> Init "interval" to 1 (smallest useful value).
> Init "times" to 1 rather than -1 (infinity), for fewer
> accidental system lockups.
>
This patch also applied with small coding style fix.
> #define DEFINE_FAULT_ATTR(name) \
> - struct fault_attr name = { .times = ATOMIC_INIT(-1), }
> + struct fault_attr name = { .interval=1, .times = ATOMIC_INIT(1), }
struct fault_attr name = { .interval = 1, .times = ATOMIC_INIT(1), }