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Message-Id: <9BA3E04B-3068-4629-B11C-1A018A9ABF3C@nocrew.org>
Date: Sun, 12 Aug 2007 20:30:46 +0200
From: Fredrik Noring <noring@...rew.org>
To: Paul Jackson <pj@....com>
Cc: linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Improving read/write/close system call reliability when used with pthreads
Paul,
Paul Jackson wrote:
> You suspected correctly - Apple Mail line wrapped it at 72 columns
> (added newlines in any line going past column 72.) This makes it
> impossible to apply the patch without alot of hand editing.
Of course, sorry about that. New try!
Regarding the FIXME: Marking bad fd:s in close currently walks all
tasks, but it ought to be possible to do this much more efficiently.
For example only tasks that actually use the file table in question.
Alternatively, only tasks that are waiters in the pipe_inode_info-
>wait queue (they are the ones that are woken up to handle the close
anyway; the wake up btw can perhaps also be more fine-grained).
I have a feeling that the latter is the most efficient, but perhaps a
bit more tricky regarding races. Plus, this puts the burden of
marking bad fd:s onto all the implementations of the f_op->closing_fd
file operation.
The rest of the bookkeeping to handle required_fds should be
efficient, I believe.
Regarding generality: For maximum benefit of being able to close all
kinds even non-pipe fd:s reliably, a lot of places need to be
updated. This is not a requirement though, as current behaviour is
maintained otherwise. (It might however be worthwhile to have
sys_read/sys_write etc. refuse -ERESTARTSYS when its fd apparently is
bad.)
Cheers,
Fredrik
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