Re: Fix for SMP deadlock in autofs4

Alexander Viro (viro@math.psu.edu)
Fri, 20 Apr 2001 05:00:04 -0400 (EDT)


On Fri, 20 Apr 2001, Jeremy Fitzhardinge wrote:

> This is a fix for a potential deadlock in autofs4's expire routine.
> It tries to use dput() while holding the dcache_lock. This isn't a
> problem in principle since dput() should only try to take the dcache_lock
> when the counter makes a transition to zero, which can't happen in
> this case. Unfortunately the generic (and only) implementation of
> atomic_dec_and_lock always takes the lock, so deadlocks.

Frankly, I'd rather add dput_locked() in dcache.c. The bug is real and
since autofs4 is not the only place like that... I'll look into that
stuff.
Al

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