[PATCH 06/19] wait_task_inactive: treat task->state and match_state as bitmasks
Change wait_task_inactive() to check "state & match_state" instead of
"state == match_state". This should not make any difference, but this
allows us to add more "stopped" bits which can be set or cleared
independently.
IOW. wait_task_inactive() assumes that if task->state != 0, it can
only be changed to TASK_RUNNING. Currently this is true, and in this
case "state & match_state" continues to work. But, unlike the current
check, it also works if task->state has other bits set while the caller
is only interested in, say, __TASK_TRACED.
Note: I think wait_task_inactive() should be cleanuped upstrean anyway,
nowadays we have TASK_WAKING and task->state != 0 doesn't necessarily
mean it is TASK_RUNNING. It also makes sense to exclude the !TASK_REPORT
bits during the check. Finally, probably this patch makes sense anyway
even without utrace. For example, a stopped _and_ traced thread could
have task->state = TASK_STOPPED | TASK_TRACED, this can be useful.
Signed-off-by: Oleg Nesterov <oleg(a)redhat.com>
---
kernel/sched.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index 3f2e502..ade7997 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2277,7 +2277,7 @@ unsigned long wait_task_inactive(struct task_struct *p, long
match_state)
* is actually now running somewhere else!
*/
while (task_running(rq, p)) {
- if (match_state && unlikely(p->state != match_state))
+ if (match_state && !likely(p->state & match_state))
return 0;
cpu_relax();
}
--
1.5.5.1