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27 March 2024, 02:37:15 UTC
Revision ab465df9dda42a997f7537c875127eeb6a88158c authored by Manfred Spraul on 26 May 2013, 09:08:52 UTC, committed by Linus Torvalds on 26 May 2013, 22:14:51 UTC 
ipc/sem.c: Fix missing wakeups in do_smart_update_queue()
 
do_smart_update_queue() is called when an operation (semop,
semctl(SETVAL), semctl(SETALL), ...) modified the array.  It must check
which of the sleeping tasks can proceed.

do_smart_update_queue() missed a few wakeups:
 - if a sleeping complex op was completed, then all per-semaphore queues
   must be scanned - not only those that were modified by *sops
 - if a sleeping simple op proceeded, then the global queue must be
   scanned again

And:
 - the test for "|sops == NULL) before scanning the global queue is not
   required: If the global queue is empty, then it doesn't need to be
   scanned - regardless of the reason for calling do_smart_update_queue()

The patch is not optimized, i.e.  even completing a wait-for-zero
operation causes a rescan.  This is done to keep the patch as simple as
possible.

Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Acked-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 89ff778
History
Tip revision: ab465df9dda42a997f7537c875127eeb6a88158c authored by Manfred Spraul on 26 May 2013, 09:08:52 UTC
ipc/sem.c: Fix missing wakeups in do_smart_update_queue()
Tip revision: ab465df
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