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Subject[PATCH 07/10] fault injection: down_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/semaphore.c | 26 ++++++++++++++++++++++++++
lib/Kconfig.debug | 6 ++++++
2 files changed, 32 insertions(+)

diff --git a/kernel/locking/semaphore.c b/kernel/locking/semaphore.c
index b8120ab..367bae3 100644
--- a/kernel/locking/semaphore.c
+++ b/kernel/locking/semaphore.c
@@ -25,6 +25,7 @@
* semaphore. If it's zero, there may be tasks waiting on the wait_list.
*/

+#include <linux/fault-inject.h>
#include <linux/compiler.h>
#include <linux/kernel.h>
#include <linux/export.h>
@@ -114,6 +115,28 @@ int down_killable(struct semaphore *sem)
}
EXPORT_SYMBOL(down_killable);

+#ifdef CONFIG_FAIL_SEMAPHORE
+DECLARE_FAULT_ATTR(fail_semaphore);
+
+static int __init fail_semaphore_debugfs(void)
+{
+ struct dentry *dir = fault_create_debugfs_attr("fail_semaphore",
+ NULL, &fail_semaphore);
+ return PTR_ERR_OR_ZERO(dir);
+}
+late_initcall(fail_semaphore_debugfs);
+
+static inline bool should_fail_semaphore(struct semaphore *sem)
+{
+ return should_fail(&fail_semaphore, 1);
+}
+#else
+static inline bool should_fail_semaphore(struct semaphore *sem)
+{
+ return false;
+}
+#endif
+
/**
* down_trylock - try to acquire the semaphore, without waiting
* @sem: the semaphore to be acquired
@@ -132,6 +155,9 @@ int down_trylock(struct semaphore *sem)
unsigned long flags;
int count;

+ if (should_fail_semaphore(sem))
+ return 1;
+
raw_spin_lock_irqsave(&sem->lock, flags);
count = sem->count - 1;
if (likely(count >= 0))
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 12ad8eb..1e134de 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1669,6 +1669,12 @@ config FAIL_RT_MUTEX
help
Provide fault-injection capability for rt_mutex_trylock().

+config FAIL_SEMAPHORE
+ bool "Fault-injection capability for semaphores"
+ depends on FAULT_INJECTION
+ help
+ Provide fault-injection capability for down_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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