Re: nbd locking problems
From: Soren Hansen
Date: Fri Jan 28 2011 - 18:12:11 EST
2011/1/28 Serge E. Hallyn <serge@xxxxxxxxxx>:
> 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.
>ÂI assume that's how it gets released around the kthread_create(). ÂI
> *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? Â(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
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Soren Hansen    Â| http://linux2go.dk/
Ubuntu Developer  Â| http://www.ubuntu.com/
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