posix-timers: Use sighand lock instead of tasklist_lock on timer deletion
authorFrederic Weisbecker <fweisbec@gmail.com>
Fri, 11 Oct 2013 15:41:11 +0000 (17:41 +0200)
committerFrederic Weisbecker <fweisbec@gmail.com>
Mon, 9 Dec 2013 15:53:51 +0000 (16:53 +0100)
commit3d7a1427e4ce545e949e9bccb75d0ca8d941d93c
tree6406beef9e8f60f7fb920c9100bdf2d60639289f
parent50875788a1d4a3f662a27ed13cd05282d835939a
posix-timers: Use sighand lock instead of tasklist_lock on timer deletion

Timer deletion doesn't need the tasklist lock.
We need to protect against:

* concurrent access to the lists p->cputime_expires and
  p->sighand->cputime_expires

* task reaping that may also delete the timer list entry

* timer firing

We already hold the timer lock which protects us against concurrent
timer firing.

The rest only need the targets sighand to be locked.
So hold it and drop the use of tasklist_lock there.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kosaki Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
kernel/posix-cpu-timers.c