[PATCH] Make RCU task_struct safe for oprofile
authorPaul E. McKenney <paulmck@us.ibm.com>
Sun, 8 Jan 2006 09:01:35 +0000 (01:01 -0800)
committerLinus Torvalds <torvalds@g5.osdl.org>
Mon, 9 Jan 2006 04:13:40 +0000 (20:13 -0800)
commit4369ef3c3e9d3bd9b879580678778f558d481e90
tree32b443b32c6de858c419f75dad07c46028359afe
parenteafbaa94691f6a1fa67c3b076caa3ce4e2920100
[PATCH] Make RCU task_struct safe for oprofile

Applying RCU to the task structure broke oprofile, because
free_task_notify() can now be called from softirq.  This means that the
task_mortuary lock must be acquired with irq disabled in order to avoid
intermittent self-deadlock.  Since irq is now disabled, the critical
section within process_task_mortuary() has been restructured to be O(1) in
order to maximize scalability and minimize realtime latency degradation.

Kudos to Wu Fengguang for finding this problem!

CC: Wu Fengguang <wfg@mail.ustc.edu.cn>
Cc: Philippe Elie <phil.el@wanadoo.fr>
Cc: John Levon <levon@movementarian.org>
Signed-off-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
drivers/oprofile/buffer_sync.c