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From: Soren Hansen <soren@linux2go.dk>
To: "Serge E. Hallyn" <serge@hallyn.com>
Cc: linux-kernel@vger.kernel.org, Dave Hansen <haveblue@us.ibm.com>
Subject: Re: nbd locking problems
Date: Sat, 29 Jan 2011 00:11:53 +0100	[thread overview]
Message-ID: <AANLkTi=1ubso_qg1dr+xOaF4s=f0Jfzchinh3dnY7jjY@mail.gmail.com> (raw)
In-Reply-To: <20110128211825.GA20707@mail.hallyn.com>

2011/1/28 Serge E. Hallyn <serge@hallyn.com>:
> Thanks for looking into this, Soren.

Sure :)

> As Dave just explained to me, BKL is released when you sleep :)

Ah, yes, that makes perfect sense.

> I assume that's how it gets released around the kthread_create().  I
> *think* you're right that the new mutex is superfluous, but I'd like to
> look through the ioctl code and make sure there's no shared state which
> we need to protect.

Yup, I've tried that and I didn't find anything, but this is very new
territory to me, so more eyes sounds great.

> I don't see how there could be, or rather, if there
> were, then it was broken before.

Good point.

> In the meantime, could you please post your patch?  (Is it the
> three-liner I'd expect?)

Indeed it is. I was holding off on posting it, because I was hoping
Pavel Machek would chime in. Pavel's commit message in [1] suggested
that there was more work to do before the BKL could be vanquished from
this driver (by changing .ioctl to .unlocked_ioctl).

I guess it can't hurt to post it, though. I'll do that in a second.

[1]: 1a2ad21128bb4eb79f3c05e5801edcc5ed3ef1d3

-- 
Soren Hansen        | http://linux2go.dk/
Ubuntu Developer    | http://www.ubuntu.com/
OpenStack Developer | http://www.openstack.org/

  parent reply	other threads:[~2011-01-28 23:11 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-01-26 10:52 Soren Hansen
2011-01-28 21:18 ` Serge E. Hallyn
2011-01-28 21:30   ` Arnd Bergmann
2011-01-28 23:11   ` Soren Hansen [this message]
2011-03-13 10:28     ` Pavel Machek
2011-01-31 19:35   ` Serge E. Hallyn
2011-01-28 23:23 ` [PATCH] nbd: Remove module-level ioctl mutex Soren Hansen
2011-01-30 15:07 nbd locking problems Paul Clements

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