diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2015-05-05 19:49:49 +0200 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2015-06-10 13:42:31 -0400 |
| commit | a0ed73fbe2457f1f47b638ee4ce8d4aae05d529a (patch) | |
| tree | 194c7b85c7cddf8e9aab4c0b996936dc0b92892f /kernel/locking | |
| parent | 71b400b61c03f9982187a92d14ad643d9aa76bff (diff) | |
sched: Handle priority boosted tasks proper in setscheduler()
[ Upstream commit 0782e63bc6fe7e2d3408d250df11d388b7799c6b ]
Ronny reported that the following scenario is not handled correctly:
T1 (prio = 10)
lock(rtmutex);
T2 (prio = 20)
lock(rtmutex)
boost T1
T1 (prio = 20)
sys_set_scheduler(prio = 30)
T1 prio = 30
....
sys_set_scheduler(prio = 10)
T1 prio = 30
The last step is wrong as T1 should now be back at prio 20.
Commit c365c292d059 ("sched: Consider pi boosting in setscheduler()")
only handles the case where a boosted tasks tries to lower its
priority.
Fix it by taking the new effective priority into account for the
decision whether a change of the priority is required.
Reported-by: Ronny Meeus <ronny.meeus@gmail.com>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
Fixes: c365c292d059 ("sched: Consider pi boosting in setscheduler()")
Link: http://lkml.kernel.org/r/alpine.DEB.2.11.1505051806060.4225@nanos
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'kernel/locking')
| -rw-r--r-- | kernel/locking/rtmutex.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c index 41d53e515914..1929ee2291f2 100644 --- a/kernel/locking/rtmutex.c +++ b/kernel/locking/rtmutex.c @@ -265,15 +265,17 @@ struct task_struct *rt_mutex_get_top_task(struct task_struct *task) } /* - * Called by sched_setscheduler() to check whether the priority change - * is overruled by a possible priority boosting. + * Called by sched_setscheduler() to get the priority which will be + * effective after the change. */ -int rt_mutex_check_prio(struct task_struct *task, int newprio) +int rt_mutex_get_effective_prio(struct task_struct *task, int newprio) { if (!task_has_pi_waiters(task)) - return 0; + return newprio; - return task_top_pi_waiter(task)->task->prio <= newprio; + if (task_top_pi_waiter(task)->task->prio <= newprio) + return task_top_pi_waiter(task)->task->prio; + return newprio; } /* |