linux-kernel - Re: [PATCH V2] UBI: add ubi_lnum_purge function to clear work queue for a lnum

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Message-ID: <1337424764.2041.12.camel@koala>
Date:	Sat, 19 May 2012 13:52:44 +0300
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Joel Reardon <joel@...mbassador.com>
Cc:	linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] UBI: add ubi_lnum_purge function to clear work queue
 for a lnum

On Sat, 2012-05-19 at 13:47 +0300, Artem Bityutskiy wrote:
> If you walk the list and read pointers, and someone else modifies them,
> you may be in trouble. You cannot traverse the list without the
> spinlock. And once you dropped the spinlock - you have to start over
> because your 'wrk' pointer may point to a non-existing object, because
> this object might have been already freed. This is why I added 2 loops.

Actually we ourselves free it in ->func() :-) I think it is saner to not
even use the list_for_each_entry(), but just take the element off the
head, unlock the spinlock use "container_of()", and call ->func(). So we
need only one loop, not 2.

-- 
Best Regards,
Artem Bityutskiy

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