Messages in this thread | | | From | Sasha Levin <> | Date | Tue, 25 Dec 2012 11:08:32 -0500 | Subject | Re: [PATCH] fb: Rework locking to fix lock ordering on takeover |
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On Tue, Dec 18, 2012 at 10:20 AM, Josh Boyer <jwboyer@gmail.com> wrote: > On Wed, Nov 21, 2012 at 7:53 AM, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote: >> On Wed, 21 Nov 2012 07:45:45 -0500 >> Josh Boyer <jwboyer@gmail.com> wrote: >> >>> On Fri, Nov 16, 2012 at 2:27 PM, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote: >>> > >>> > [The fb maintainer appears to be absent at the moment]. >>> > >>> > This is needed to fix a pile of lockdep splats that now show up because console_lock() >>> > is being properly audited. Hugh Dickins and Sasha Levin have tested it and both reports >>> > all looks good. This is probably not the whole story - the entire fb layer has locking >>> > confusion problems that were previously hidden but it seems to get the ones people hit >>> > in testing. This hopefully explains a few of the weird fb hangs that have been floating >>> > around forever. >>> > >>> > From: Alan Cox <alan@linux.intel.com> >>> > >>> > Adjust the console layer to allow a take over call where the caller already >>> > holds the locks. Make the fb layer lock in order. >>> > >>> > This s partly a band aid, the fb layer is terminally confused about the >>> > locking rules it uses for its notifiers it seems. >>> > >>> > Signed-off-by: Alan Cox <alan@linux.intel.com> >>> >>> Should this eventually get into the stable trees? >> >> Thats a question I'm not sure about at this point. I think the bug is >> real but not caught by the lock checker in older trees but I've not >> investigated. > > So... this patch seems to still be twisting in the wind. It should > probably be headed into 3.8 at this point, shouldn't it?
Indeed it should. I'm seeing the original warnings in 3.8-rc1 and have to carry this patch to avoid them.
Thanks, Sasha
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