do_wait-wakeup-optimization: fix child_wait_callback()->eligible_child() usage
authorOleg Nesterov <oleg@redhat.com>
Wed, 23 Sep 2009 22:56:48 +0000 (15:56 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 24 Sep 2009 14:21:00 +0000 (07:21 -0700)
commit5c01ba49e6647d86bc7576105f82027200d1f303
tree700aa5dbda7c726e8b60803225587a1bc4fdbdb5
parentb4fe51823d797d6959b2eee7868023e61606daa9
do_wait-wakeup-optimization: fix child_wait_callback()->eligible_child() usage

child_wait_callback()->eligible_child() is not right, we can miss the
wakeup if the task was detached before __wake_up_parent() and the caller
of do_wait() didn't use __WALL.

Move ->wo_pid checks from eligible_child() to the new helper,
eligible_pid(), and change child_wait_callback() to use it instead of
eligible_child().

Note: actually I think it would be better to fix the __WCLONE check in
eligible_child(), it doesn't look exactly right.  But it is not clear what
is the supposed behaviour, and any change is user-visible.

Reported-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Tested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/exit.c