diff options
author | Kirill Tkhai <tkhai@yandex.ru> | 2014-05-20 13:33:42 +0400 |
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committer | Show Liu <show.liu@linaro.org> | 2014-06-18 12:05:24 +0800 |
commit | f4c60f94f1a1385602a488cfc1ef2180e15309bb (patch) | |
tree | 9631d1c81cda92730d83579d11bb240524df5fb8 /drivers/ipack | |
parent | ccdbf63dc46377d8dc921b948fc073a4ded3348c (diff) |
sched/dl: Fix race in dl_task_timer()
commit 0f397f2c90ce68821ee864c2c53baafe78de765d upstream.
Throttled task is still on rq, and it may be moved to other cpu
if user is playing with sched_setaffinity(). Therefore, unlocked
task_rq() access makes the race.
Juri Lelli reports he got this race when dl_bandwidth_enabled()
was not set.
Other thing, pointed by Peter Zijlstra:
"Now I suppose the problem can still actually happen when
you change the root domain and trigger a effective affinity
change that way".
To fix that we do the same as made in __task_rq_lock(). We do not
use __task_rq_lock() itself, because it has a useful lockdep check,
which is not correct in case of dl_task_timer(). We do not need
pi_lock locked here. This case is an exception (PeterZ):
"The only reason we don't strictly need ->pi_lock now is because
we're guaranteed to have p->state == TASK_RUNNING here and are
thus free of ttwu races".
Signed-off-by: Kirill Tkhai <tkhai@yandex.ru>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/3056991400578422@web14g.yandex.ru
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/ipack')
0 files changed, 0 insertions, 0 deletions