tracehook: wait_task_inactive

This extends wait_task_inactive() with a new argument so it can be used in
a "soft" mode where it will check for the task changing state unexpectedly
and back off.  There is no change to existing callers.  This lays the
groundwork to allow robust, noninvasive tracing that can try to sample a
blocked thread but back off safely if it wakes up.

Signed-off-by: Roland McGrath <roland@redhat.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Reviewed-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 6111c27491b1..96cff2f8710b 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -176,7 +176,7 @@ void kthread_bind(struct task_struct *k, unsigned int cpu)
                 return;
         }
         /* Must have done schedule() in kthread() before we set_task_cpu */
-        wait_task_inactive(k);
+        wait_task_inactive(k, 0);
         set_task_cpu(k, cpu);
         k->cpus_allowed = cpumask_of_cpu(cpu);
         k->rt.nr_cpus_allowed = 1;