[PATCH 06/10] fault injection: rt_mutex_trylock() fault injection

[Vegard Nossum]

Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
---
 kernel/locking/rtmutex.c | 26 ++++++++++++++++++++++++++
 lib/Kconfig.debug        |  6 ++++++
 2 files changed, 32 insertions(+)

diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 1ec0f48..22ff6da 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -10,6 +10,7 @@
  *
  *  See Documentation/locking/rt-mutex-design.txt for details.
  */
+#include <linux/fault-inject.h>
 #include <linux/spinlock.h>
 #include <linux/export.h>
 #include <linux/sched.h>
@@ -1465,6 +1466,28 @@ rt_mutex_timed_lock(struct rt_mutex *lock, struct hrtimer_sleeper *timeout)
 }
 EXPORT_SYMBOL_GPL(rt_mutex_timed_lock);
 
+#ifdef CONFIG_FAIL_RT_MUTEX
+DECLARE_FAULT_ATTR(fail_rtmutex);
+
+static int __init fail_rtmutex_debugfs(void)
+{
+	struct dentry *dir = fault_create_debugfs_attr("fail_rtmutex",
+		NULL, &fail_rtmutex);
+	return PTR_ERR_OR_ZERO(dir);
+}
+late_initcall(fail_rtmutex_debugfs);
+
+static inline bool should_fail_rtmutex(struct rt_mutex *lock)
+{
+	return should_fail(&fail_rtmutex, 1);
+}
+#else
+static inline bool should_fail_rtmutex(struct rt_mutex *lock)
+{
+	return false;
+}
+#endif
+
 /**
  * rt_mutex_trylock - try to lock a rt_mutex
  *
@@ -1481,6 +1504,9 @@ int __sched rt_mutex_trylock(struct rt_mutex *lock)
 	if (WARN_ON_ONCE(in_irq() || in_nmi() || in_serving_softirq()))
 		return 0;
 
+	if (should_fail_rtmutex(lock))
+		return 0;
+
 	return rt_mutex_fasttrylock(lock, rt_mutex_slowtrylock);
 }
 EXPORT_SYMBOL_GPL(rt_mutex_trylock);
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 7e9a9b2e..12ad8eb 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1663,6 +1663,12 @@ config FAIL_MUTEX
 	help
 	  Provide fault-injection capability for mutex_trylock().
 
+config FAIL_RT_MUTEX
+	bool "Fault-injection capability for RT mutexes"
+	depends on FAULT_INJECTION && RT_MUTEXES
+	help
+	  Provide fault-injection capability for rt_mutex_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