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| author | Xunlei Pang <xlpang@redhat.com> | 2017-03-23 15:56:07 +0100 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2017-04-04 11:44:05 +0200 |
| commit | 2a1c6029940675abb2217b590512dbf691867ec4 (patch) | |
| tree | a975e4e9f643d86a904b6314a3bab21b023fd6cc /kernel/locking/rtmutex_common.h | |
| parent | 38bffdac071b720db627bfd2b125a2802a04d419 (diff) | |
| download | linux-stable-2a1c6029940675abb2217b590512dbf691867ec4.tar.gz linux-stable-2a1c6029940675abb2217b590512dbf691867ec4.tar.bz2 linux-stable-2a1c6029940675abb2217b590512dbf691867ec4.zip | |
rtmutex: Deboost before waking up the top waiter
We should deboost before waking the high-priority task, such that we
don't run two tasks with the same "state" (priority, deadline,
sched_class, etc).
In order to make sure the boosting task doesn't start running between
unlock and deboost (due to 'spurious' wakeup), we move the deboost
under the wait_lock, that way its serialized against the wait loop in
__rt_mutex_slowlock().
Doing the deboost early can however lead to priority-inversion if
current would get preempted after the deboost but before waking our
high-prio task, hence we disable preemption before doing deboost, and
enabling it after the wake up is over.
This gets us the right semantic order, but most importantly however;
this change ensures pointer stability for the next patch, where we
have rt_mutex_setprio() cache a pointer to the top-most waiter task.
If we, as before this change, do the wakeup first and then deboost,
this pointer might point into thin air.
[peterz: Changelog + patch munging]
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Xunlei Pang <xlpang@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: juri.lelli@arm.com
Cc: bigeasy@linutronix.de
Cc: mathieu.desnoyers@efficios.com
Cc: jdesfossez@efficios.com
Cc: bristot@redhat.com
Link: http://lkml.kernel.org/r/20170323150216.110065320@infradead.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/locking/rtmutex_common.h')
| -rw-r--r-- | kernel/locking/rtmutex_common.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/locking/rtmutex_common.h b/kernel/locking/rtmutex_common.h index b1ccfea2effe..a09c02982391 100644 --- a/kernel/locking/rtmutex_common.h +++ b/kernel/locking/rtmutex_common.h @@ -122,7 +122,7 @@ extern void rt_mutex_futex_unlock(struct rt_mutex *lock); extern bool __rt_mutex_futex_unlock(struct rt_mutex *lock, struct wake_q_head *wqh); -extern void rt_mutex_adjust_prio(struct task_struct *task); +extern void rt_mutex_postunlock(struct wake_q_head *wake_q, bool deboost); #ifdef CONFIG_DEBUG_RT_MUTEXES # include "rtmutex-debug.h" |