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Date: Thu, 06 Dec 2007 17:40:36 -0800 From: Daniel Walker <dwalker@...sta.com> To: Kevin Winchester <kjwinchester@...il.com> Cc: Ingo Molnar <mingo@...e.hu>, akpm@...ux-foundation.org, linux-kernel@...r.kernel.org, linux@...mer.net, jonathan@...masters.org, matthias.kaehlcke@...il.com Subject: Re: Possible locking issue in viotape.c On Thu, 2007-12-06 at 21:29 -0400, Kevin Winchester wrote: > Daniel Walker wrote: > > > > I've posted all the ones I've done so far .. > > > > ftp://source.mvista.com/pub/dwalker/sem2mutex-2.6.24-rc4/ > > > > Feel free to review or test them.. I've found it pretty easy to simply > > grep for certain class of semaphore usage, check if it's conforming to > > the mutex requirements, then convert it or not.. Checking them is > > getting to be a habit, so I don't think a list would help me.. However, > > someone else might be able to use it.. > > > > Thanks, that helps me not duplicate anything. One of the first ones I > was looking at (before your post) was viotape.c, which is in your patch > set. However, looking at the uses of the semaphore, I see that on line > 409-410 the following code: > > if (noblock) > return count; > > which seems to ignore the fact that the semaphore has been downed (not > to mention the dma buffer and op struct allocations. I think it should be: > > if (noblock) > ret = count; > goto free_dma; > > instead. Do you want to make sure I'm right about that and fold it into > your patch? Or have you already submitted your patch (or should it be > in a separate patch? Alternatively, I can submit the patch if you don't > want to bother with it. viotape was one of the first I started converting, but later I noticed the same thing you found above. I have it commented out of my series for that reason .. I think this noblock path is actually doing what the author intended.. There are a few stray up() calls related to event handling and ioctls , and I think those are used to release the semaphore.. Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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