diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2023-09-08 19:22:51 +0300 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2023-09-20 10:31:12 +0300 |
| commit | 6b596e62ed9f90c4a97e68ae1f7b1af5beeb3c05 (patch) | |
| tree | 5fdde551fcf4a48f0a1046c34b6d994e0be0ffd6 /include/linux/sched/rt.h | |
| parent | de1474b46d889ee0367f6e71d9adfeb0711e4a8d (diff) | |
| download | linux-6b596e62ed9f90c4a97e68ae1f7b1af5beeb3c05.tar.xz | |
sched: Provide rt_mutex specific scheduler helpers
With PREEMPT_RT there is a rt_mutex recursion problem where
sched_submit_work() can use an rtlock (aka spinlock_t). More
specifically what happens is:
mutex_lock() /* really rt_mutex */
...
__rt_mutex_slowlock_locked()
task_blocks_on_rt_mutex()
// enqueue current task as waiter
// do PI chain walk
rt_mutex_slowlock_block()
schedule()
sched_submit_work()
...
spin_lock() /* really rtlock */
...
__rt_mutex_slowlock_locked()
task_blocks_on_rt_mutex()
// enqueue current task as waiter *AGAIN*
// *CONFUSION*
Fix this by making rt_mutex do the sched_submit_work() early, before
it enqueues itself as a waiter -- before it even knows *if* it will
wait.
[[ basically Thomas' patch but with different naming and a few asserts
added ]]
Originally-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20230908162254.999499-5-bigeasy@linutronix.de
Diffstat (limited to 'include/linux/sched/rt.h')
| -rw-r--r-- | include/linux/sched/rt.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/sched/rt.h b/include/linux/sched/rt.h index 994c25640e15..b2b9e6eb9683 100644 --- a/include/linux/sched/rt.h +++ b/include/linux/sched/rt.h @@ -30,6 +30,10 @@ static inline bool task_is_realtime(struct task_struct *tsk) } #ifdef CONFIG_RT_MUTEXES +extern void rt_mutex_pre_schedule(void); +extern void rt_mutex_schedule(void); +extern void rt_mutex_post_schedule(void); + /* * Must hold either p->pi_lock or task_rq(p)->lock. */ |