taskstats: add_del_listener() should ignore !valid listeners
authorOleg Nesterov <oleg@redhat.com>
Wed, 3 Aug 2011 23:21:05 +0000 (16:21 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Thu, 4 Aug 2011 00:25:20 +0000 (14:25 -1000)
commita7295898a1d2e501427f557111c2b4bdfc90b1ed
tree143ce6e69d8aa795494120a00c62ca0ade8bac40
parentdfc428b656c4693a2334a8d9865b430beddb562a
taskstats: add_del_listener() should ignore !valid listeners

When send_cpu_listeners() finds the orphaned listener it marks it as
!valid and drops listeners->sem.  Before it takes this sem for writing,
s->pid can be reused and add_del_listener() can wrongly try to re-use
this entry.

Change add_del_listener() to check ->valid = T.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Vasiliy Kulikov <segoon@openwall.com>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/taskstats.c