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  1. 16 Mar, 2009 4 commits
    • Jonathan Corbet's avatar
      Rationalize fasync return values · 60aa4924
      Jonathan Corbet authored 
      Most fasync implementations do something like:

     return fasync_helper(...);

But fasync_helper() will return a positive value at times - a feature used
in at least one place.  Thus, a number of other drivers do:

     err = fasync_helper(...);
     if (err < 0)
             return err;
     return 0;

In the interests of consistency and more concise code, it makes sense to
map positive return values onto zero where ->fasync() is called.

Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
      60aa4924
    • Jonathan Corbet's avatar
      Move FASYNC bit handling to f_op->fasync() · 76398425
      Jonathan Corbet authored 
      Removing the BKL from FASYNC handling ran into the challenge of keeping the
setting of the FASYNC bit in filp->f_flags atomic with regard to calls to
the underlying fasync() function.  Andi Kleen suggested moving the handling
of that bit into fasync(); this patch does exactly that.  As a result, we
have a couple of internal API changes: fasync() must now manage the FASYNC
bit, and it will be called without the BKL held.

As it happens, every fasync() implementation in the kernel with one
exception calls fasync_helper().  So, if we make fasync_helper() set the
FASYNC bit, we can avoid making any changes to the other fasync()
functions - as long as those functions, themselves, have proper locking.
Most fasync() implementations do nothing but call fasync_helper() - which
has its own lock - so they are easily verified as correct.  The BKL had
already been pushed down into the rest.

The networking code has its own version of fasync_helper(), so that code
has been augmented with explicit FASYNC bit handling.

Cc: Al Viro <viro@ZenIV.linux.org.uk>
Cc: David Miller <davem@davemloft.net>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
      76398425
    • Jonathan Corbet's avatar
      Use f_lock to protect f_flags · db1dd4d3
      Jonathan Corbet authored 
      Traditionally, changes to struct file->f_flags have been done under BKL
protection, or with no protection at all.  This patch causes all f_flags
changes after file open/creation time to be done under protection of
f_lock.  This allows the removal of some BKL usage and fixes a number of
longstanding (if microscopic) races.
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
      db1dd4d3
    • Jonathan Corbet's avatar
      Rename struct file->f_ep_lock · 68499914
      Jonathan Corbet authored 
      This lock moves out of the CONFIG_EPOLL ifdef and becomes f_lock.  For now,
epoll remains the only user, but a future patch will use it to protect
f_flags as well.

Cc: Davide Libenzi <davidel@xmailserver.org>
Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
Signed-off-by: default avatarJonathan Corbet <corbet@lwn.net>
      68499914
  3. 13 Mar, 2009 2 commits
  5. 12 Mar, 2009 34 commits
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