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linux/kernel/locking
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Thomas Gleixner 0782e63bc6 sched: Handle priority boosted tasks proper in setscheduler() 
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 c365c292d0 ("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: c365c292d0 ("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>
2015-05-08 11:53:55 +02:00
..
lglock.c
lockdep.c lockdep: Make print_lock() robust against concurrent release 2015-04-17 09:42:14 +02:00
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
locktorture.c
Makefile
mcs_spinlock.h locking: Remove ACCESS_ONCE() usage 2015-02-24 08:44:16 +01:00
mutex-debug.c
mutex-debug.h
mutex.c locking/mutex: Further simplify mutex_spin_on_owner() 2015-04-09 08:10:23 +02:00
mutex.h
osq_lock.c locking: Remove ACCESS_ONCE() usage 2015-02-24 08:44:16 +01:00
percpu-rwsem.c
qrwlock.c
rtmutex-debug.c
rtmutex-debug.h
rtmutex-tester.c
rtmutex.c sched: Handle priority boosted tasks proper in setscheduler() 2015-05-08 11:53:55 +02:00
rtmutex.h
rtmutex_common.h
rwsem-spinlock.c locking/rwsem: Document barrier need when waking tasks 2015-02-18 16:57:10 +01:00
rwsem-xadd.c locking/rwsem: Fix lock optimistic spinning when owner is not running 2015-03-07 09:50:49 +01:00
rwsem.c locking/rwsem: Set lock ownership ASAP 2015-02-18 16:57:13 +01:00
rwsem.h locking/rwsem: Set lock ownership ASAP 2015-02-18 16:57:13 +01:00
semaphore.c
spinlock.c
spinlock_debug.c