Messages in this thread |  | | Date | Fri, 30 Aug 2002 09:55:54 +0200 (CEST) | From | Ingo Molnar <> | Subject | Re: [patch] scheduler fixes, 2.5.32-BK |
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> - changes the migration code to use struct completion. Andrew pointed out > that there might be a small window in where the up() touches the > semaphore while the waiting task goes on and frees its stack. And > completion is more suited for this kind of stuff anyway.
actually, i think the race does not exist. up() is perfectly safely done on the on-stack semaphore, because both the wake_up() done by __up() and the __down() path takes the waitqueue spinlock, so i cannot see where the up() touches the semaphore after the down()-ed task has been woken up.
the second argument still holds though - a completion is probably slightly cheaper in this case.
Ingo
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