Messages in this thread | | | Date | Wed, 27 Aug 2008 09:19:22 +0200 | From | Jens Axboe <> | Subject | Re: [GIT PULL] block bits |
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On Tue, Aug 26 2008, Jeremy Fitzhardinge wrote: > Jens Axboe wrote: > > On Tue, Aug 26 2008, Linus Torvalds wrote: > > > >> On Tue, 26 Aug 2008, Jens Axboe wrote: > >> > >>> I'll move those 1-2 patches to the 2.6.28 branch and resubmit the rest > >>> for you. > >>> > >> You will *delete* the absolute crap locking patch, that has no way of > >> being even 2.6.28 material. > >> > > > > Yeah, I thought that was obvious, I'll bounce it back to the Xen folks. > > > > Which, what? Was there an objection to one of the blkfront patches? (I > don't remember anything locking related in there anyway.)
I see Linus' initial reply didn't make it to the list, not sure why. This is what he said:
"it's so _incredibly_ broken that I refuse to pull any of the rest either, because the queue is obviously utter crap.
In fact, even the "explanation" for that one is shit:
"It shouldn't matter if an interrupt comes in whilst blkif_io_lock is held, as it will block on the lock [...]"
where "as it will block" is apparently shorthand for "as it will deadlock and kill the machine"."
This is the patch in question:
http://git.kernel.dk/?p=linux-2.6-block.git;a=commitdiff;h=b58e9034c5e2424723948a63712eaf1332a76ab8;hp=5814f8d589a1daef3b1a6f3731fd65a858dc8466
and it doesn indeed look like crap. It DOES matter if an interrupt comes in on the local CPU while you are holding the blkif_io_lock, you'd be dead on the spot spinning forever in the irq handler.
-- Jens Axboe
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