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authorDavidlohr Bueso <dave@stgolabs.net>2015-02-01 22:16:24 -0800
committerIngo Molnar <mingo@kernel.org>2015-02-04 07:57:42 +0100
commitafffc6c1805d98e08e778cddb644a666e78cfcfd (patch)
tree86ad29607790194934447f45787de73314bd5397 /kernel
parent73105994c57d06e40a33ab5a716db04e898b4c05 (diff)
locking/rtmutex: Optimize setting task running after being blocked
We explicitly mark the task running after returning from a __rt_mutex_slowlock() call, which does the actual sleeping via wait-wake-trylocking. As such, this patch does two things: (1) refactors the code so that setting current to TASK_RUNNING is done by __rt_mutex_slowlock(), and not by the callers. The downside to this is that it becomes a bit unclear when at what point we block. As such I've added a comment that the task blocks when calling __rt_mutex_slowlock() so readers can figure out when it is running again. (2) relaxes setting current's state through __set_current_state(), instead of it's more expensive barrier alternative. There was no need for the implied barrier as we're obviously not planning on blocking. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: http://lkml.kernel.org/r/1422857784.18096.1.camel@stgolabs.net Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/locking/rtmutex.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 7c98873a3077..3059bc2f022d 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1130,6 +1130,7 @@ __rt_mutex_slowlock(struct rt_mutex *lock, int state,
set_current_state(state);
}
+ __set_current_state(TASK_RUNNING);
return ret;
}
@@ -1188,10 +1189,9 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
ret = task_blocks_on_rt_mutex(lock, &waiter, current, chwalk);
if (likely(!ret))
+ /* sleep on the mutex */
ret = __rt_mutex_slowlock(lock, state, timeout, &waiter);
- set_current_state(TASK_RUNNING);
-
if (unlikely(ret)) {
remove_waiter(lock, &waiter);
rt_mutex_handle_deadlock(ret, chwalk, &waiter);
@@ -1626,10 +1626,9 @@ int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
set_current_state(TASK_INTERRUPTIBLE);
+ /* sleep on the mutex */
ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
- set_current_state(TASK_RUNNING);
-
if (unlikely(ret))
remove_waiter(lock, waiter);