Messages in this thread |  | | | Date | Wed, 12 Aug 2009 06:48:37 +0200 | | From | Nick Piggin <> | | Subject | Re: [patch 4/4] ipc: sem optimise simple operations |
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On Wed, Aug 12, 2009 at 12:07:11AM +0400, Cyrill Gorcunov wrote: > [npiggin@suse.de - Tue, Aug 11, 2009 at 09:09:06PM +1000] > ... > | +static void update_queue_simple(struct sem_array *sma, ushort semnum) > | +{ > | + if (unlikely(sma->complex_count)) { > | + update_queue(sma); > | + } else { > | + struct sem *sem; > | + > | + sem = &sma->sem_base[semnum]; > | + if (sem->semval > 0) > | + update_negv_queue(sma, sem); > | + if (sem->semval == 0) > | + update_zero_queue(sma, sem); > | + } > | +} > | + > ... > > Hi Nick, > > mostly probably miss something but can't we trgigger BUG_ON at updating > zero queue if semaphore was created with undo list and via new operation > reached -ERANGE on undo value? > > Again, I could be missing something or plain wrong. Just a thought.
Hi Cyrill,
Thanks for looking... Hmm, you mean BUG_ON(error) due to try_atomic_semop returning -ERANGE? I think it should not be possible because it should prevent any operation from bringing the undo list to -ERANGE so then any operation which does not modify the sem value should not go out of range I think.
(I think it would be a bug if we ever return -ERANGE for a wait-for-zero operation).
Thanks, Nick
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