Re: [GIT PULL] killable rwsems for v4.7

From	Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups	linux.kernel
Subject	Re: [GIT PULL] killable rwsems for v4.7
Date	2016-05-17 20:40 +0200
Message-ID	<rzS4q-875-23@gated-at.bofh.it> (permalink)
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On Tue, May 17, 2016 at 11:05 AM, Al Viro <viro@zeniv.linux.org.uk> wrote:
>
> I'm not sure - killable write is needed in a bunch of places there (and the
> only reason it's not used in #work.lookups is to avoid even more merge
> headache; as soon as both are merged, I'll post a trivial followup switching
> half a dozen places to it), killable read...  Do we really need it?
> The only plausible user right now (->i_rwsem one, that is) is parallel readdir.
> And I'm not convinced that we need to make that one killable.  We can
> (down_read_killable seems to be easy to put together), but is it worth
> using it in that usecase?

It may not be a big deal.

Especially since I also expect to merge the "stop readdir in the
middle if a signal is pending" patch that was buggy last time around
but Ted has a fixed and extended version of it.

So together with the fact that most of the time we hopefully end up
not blocking anyway (because taking the rwsem for writing is hopefully
less common) I guess that the possible latency issue just isn't going
to ever be noticeable.

So let's just see if we ever hit a situation where people end up even
noticing the issue.

              Linus

Thread

[GIT PULL] killable rwsems for v4.7 Ingo Molnar <mingo@kernel.org> - 2016-05-16 17:00 +0200
  Re: [GIT PULL] killable rwsems for v4.7 Linus Torvalds <torvalds@linux-foundation.org> - 2016-05-16 22:40 +0200
    Re: [GIT PULL] killable rwsems for v4.7 Michal Hocko <mhocko@kernel.org> - 2016-05-17 09:10 +0200
      Re: [GIT PULL] killable rwsems for v4.7 Al Viro <viro@ZenIV.linux.org.uk> - 2016-05-17 20:10 +0200
        Re: [GIT PULL] killable rwsems for v4.7 Linus Torvalds <torvalds@linux-foundation.org> - 2016-05-17 20:40 +0200
    Re: [GIT PULL] killable rwsems for v4.7 Peter Zijlstra <peterz@infradead.org> - 2016-05-17 13:10 +0200

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