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Subject[PATCH 08/10] fault injection: down_{read,write}_trylock() fault injection
Date
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
---
kernel/locking/rwsem.c | 35 +++++++++++++++++++++++++++++++++--
lib/Kconfig.debug | 6 ++++++
2 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/kernel/locking/rwsem.c b/kernel/locking/rwsem.c
index 45ba475..e52ffd3 100644
--- a/kernel/locking/rwsem.c
+++ b/kernel/locking/rwsem.c
@@ -4,6 +4,7 @@
* Derived from asm-i386/semaphore.h
*/

+#include <linux/fault-inject.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/sched.h>
@@ -13,6 +14,28 @@

#include "rwsem.h"

+#ifdef CONFIG_FAIL_RW_SEMAPHORE
+DECLARE_FAULT_ATTR(fail_rwsem);
+
+static int __init fail_rwsem_debugfs(void)
+{
+ struct dentry *dir = fault_create_debugfs_attr("fail_rwsem",
+ NULL, &fail_rwsem);
+ return PTR_ERR_OR_ZERO(dir);
+}
+late_initcall(fail_rwsem_debugfs);
+
+static inline bool should_fail_rwsem(struct rw_semaphore *sem)
+{
+ return should_fail(&fail_rwsem, 1);
+}
+#else
+static inline bool should_fail_rwsem(struct rw_semaphore *sem)
+{
+ return false;
+}
+#endif
+
/*
* lock for reading
*/
@@ -32,8 +55,12 @@ EXPORT_SYMBOL(down_read);
*/
int down_read_trylock(struct rw_semaphore *sem)
{
- int ret = __down_read_trylock(sem);
+ int ret;
+
+ if (should_fail_rwsem(sem))
+ return 0;

+ ret = __down_read_trylock(sem);
if (ret == 1) {
rwsem_acquire_read(&sem->dep_map, 0, 1, _RET_IP_);
rwsem_set_reader_owned(sem);
@@ -81,8 +108,12 @@ EXPORT_SYMBOL(down_write_killable);
*/
int down_write_trylock(struct rw_semaphore *sem)
{
- int ret = __down_write_trylock(sem);
+ int ret;
+
+ if (should_fail_rwsem(sem))
+ return 0;

+ ret = __down_write_trylock(sem);
if (ret == 1) {
rwsem_acquire(&sem->dep_map, 0, 1, _RET_IP_);
rwsem_set_owner(sem);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 1e134de..342f0a1f 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1675,6 +1675,12 @@ config FAIL_SEMAPHORE
help
Provide fault-injection capability for down_trylock().

+config FAIL_RW_SEMAPHORE
+ bool "Fault-injection capability for RW semaphores"
+ depends on FAULT_INJECTION
+ help
+ Provide fault-injection capability for down_{read,write}_trylock().
+
config FAULT_INJECTION_DEBUG_FS
bool "Debugfs entries for fault-injection capabilities"
depends on FAULT_INJECTION && SYSFS && DEBUG_FS
--
2.10.0.479.g221bd91
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