[patch 14/14] locking/rtmutex: Restrict the trylock WARN_ON() to debug

Thomas Gleixner
2021-03-23T21:42:24Z

The warning as written is expensive and not really required for a
production kernel. Make it depend on rt mutex debugging and use !in_task()
for the condition which generates far better code and gives the same
answer.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
kernel/locking/rtmutex.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)

--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1445,9 +1445,8 @@ EXPORT_SYMBOL_GPL(rt_mutex_lock_interrup
*
* @lock: the rt_mutex to be locked
*
- * This function can only be called in thread context. It's safe to
- * call it from atomic regions, but not from hard interrupt or soft
- * interrupt context.
+ * This function can only be called in thread context. It's safe to call it
+ * from atomic regions, but not from hard or soft interrupt context.
*
* Returns 1 on success and 0 on contention
*/
@@ -1455,7 +1454,7 @@ int __sched rt_mutex_trylock(struct rt_m
{
int ret;

- if (WARN_ON_ONCE(in_irq() || in_nmi() || in_serving_softirq()))
+ if (IS_ENABLED(CONFIG_RT_MUTEX_DEBUG) && WARN_ON_ONCE(!in_task()))
return 0;

if (likely(rt_mutex_cmpxchg_acquire(lock, NULL, current)))