[PATCH RT 22/25][RFC 3.0.23-rt39-rc1] sched/rt: Fix wait_task_interactive() to test rt_spin_lock state

[Steven Rostedt]

From: Steven Rostedt <rostedt@xxxxxxxxxxx>

The wait_task_interactive() will have a task sleep waiting for another
task to have a certain state. But it ignores the rt_spin_locks state
and can return with an incorrect result if the task it is waiting
for is blocked on a rt_spin_lock() and is waking up.

The rt_spin_locks save the tasks state in the saved_state field
and the wait_task_interactive() must also test that state.

Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Carsten Emde <C.Emde@xxxxxxxxx>
Cc: John Kacur <jkacur@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Clark Williams <clark.williams@xxxxxxxxx>
Cc: stable-rt@xxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20120301190345.979435764@xxxxxxxxxxx
Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
---
 kernel/sched.c |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/kernel/sched.c b/kernel/sched.c
index e5ef7a8..df30481 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2284,7 +2284,8 @@ 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 && unlikely(p->state != match_state)
+			    && unlikely(p->saved_state != match_state))
 				return 0;
 			cpu_relax();
 		}
@@ -2299,7 +2300,8 @@ unsigned long wait_task_inactive(struct task_struct *p, long match_state)
 		running = task_running(rq, p);
 		on_rq = p->on_rq;
 		ncsw = 0;
-		if (!match_state || p->state == match_state)
+		if (!match_state || p->state == match_state
+		    || p->saved_state == match_state)
 			ncsw = p->nvcsw | LONG_MIN; /* sets MSB */
 		task_rq_unlock(rq, p, &flags);
 
-- 
1.7.8.3


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