Re: [RFC, PATCH] locks: remove posix deadlock detection

Matthew Wilcox
2007-10-28T18:27:58Z

On Sun, Oct 28, 2007 at 01:43:21PM -0400, J. Bruce Fields wrote:
> We currently attempt to return -EDEALK to blocking fcntl() file locking
> requests that would create a cycle in the graph of tasks waiting on
> locks.
>
> This is inefficient: in the general case it requires us determining
> whether we're adding a cycle to an arbitrary directed acyclic graph.
> And this calculation has to be performed while holding a lock (currently
> the BKL) that prevents that graph from changing.
>
> It has historically been a source of bugs; most recently it was noticed
> that it could loop indefinitely while holding the BKL.

It can also return -EDEADLK spuriously. So yeah, just kill it.

--
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