1. 09 2月, 2010 2 次提交
  2. 08 2月, 2010 1 次提交
    • L
      Fix race in tty_fasync() properly · 80e1e823
      Linus Torvalds 提交于
      This reverts commit 70362511 ("tty: fix race in tty_fasync") and
      commit b04da8bf ("fnctl: f_modown should call write_lock_irqsave/
      restore") that tried to fix up some of the fallout but was incomplete.
      
      It turns out that we really cannot hold 'tty->ctrl_lock' over calling
      __f_setown, because not only did that cause problems with interrupt
      disables (which the second commit fixed), it also causes a potential
      ABBA deadlock due to lock ordering.
      
      Thanks to Tetsuo Handa for following up on the issue, and running
      lockdep to show the problem.  It goes roughly like this:
      
       - f_getown gets filp->f_owner.lock for reading without interrupts
         disabled, so an interrupt that happens while that lock is held can
         cause a lockdep chain from f_owner.lock -> sighand->siglock.
      
       - at the same time, the tty->ctrl_lock -> f_owner.lock chain that
         commit 70362511 introduced, together with the pre-existing
         sighand->siglock -> tty->ctrl_lock chain means that we have a lock
         dependency the other way too.
      
      So instead of extending tty->ctrl_lock over the whole __f_setown() call,
      we now just take a reference to the 'pid' structure while holding the
      lock, and then release it after having done the __f_setown.  That still
      guarantees that 'struct pid' won't go away from under us, which is all
      we really ever needed.
      Reported-and-tested-by: NTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
      Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
      Acked-by: NAmérico Wang <xiyou.wangcong@gmail.com>
      Cc: stable@kernel.org
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      80e1e823
  3. 07 2月, 2010 6 次提交
  4. 06 2月, 2010 1 次提交
  5. 05 2月, 2010 6 次提交
  6. 04 2月, 2010 2 次提交
  7. 03 2月, 2010 16 次提交
  8. 01 2月, 2010 3 次提交
  9. 31 1月, 2010 2 次提交
  10. 30 1月, 2010 1 次提交
    • L
      Split 'flush_old_exec' into two functions · 221af7f8
      Linus Torvalds 提交于
      'flush_old_exec()' is the point of no return when doing an execve(), and
      it is pretty badly misnamed.  It doesn't just flush the old executable
      environment, it also starts up the new one.
      
      Which is very inconvenient for things like setting up the new
      personality, because we want the new personality to affect the starting
      of the new environment, but at the same time we do _not_ want the new
      personality to take effect if flushing the old one fails.
      
      As a result, the x86-64 '32-bit' personality is actually done using this
      insane "I'm going to change the ABI, but I haven't done it yet" bit
      (TIF_ABI_PENDING), with SET_PERSONALITY() not actually setting the
      personality, but just the "pending" bit, so that "flush_thread()" can do
      the actual personality magic.
      
      This patch in no way changes any of that insanity, but it does split the
      'flush_old_exec()' function up into a preparatory part that can fail
      (still called flush_old_exec()), and a new part that will actually set
      up the new exec environment (setup_new_exec()).  All callers are changed
      to trivially comply with the new world order.
      Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
      Cc: stable@kernel.org
      Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      221af7f8