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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>
This commit is contained in:
Oleg Nesterov 2011-08-03 16:21:05 -07:00 committed by Linus Torvalds
parent dfc428b656
commit a7295898a1
1 changed files with 1 additions and 1 deletions
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2
kernel/taskstats.c
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@ -304,7 +304,7 @@ static int add_del_listener(pid_t pid, const struct cpumask *mask, int isadd)
listeners = &per_cpu(listener_array, cpu);
down_write(&listeners->sem);
list_for_each_entry(s2, &listeners->list, list) {
if (s2->pid == pid)
if (s2->pid == pid && s2->valid)
goto exists;
}
list_add(&s->list, &listeners->list);