sched/deadline: Fix races between rt_mutex_setprio() and dl_task_timer()

[firefly-linux-kernel-4.4.55.git] / kernel / sched / deadline.c

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 92279eaf0ef278b7e228d03e9675a0454d663a3d..46167899d852bfe890404752a9d13a24ee099434 100644 (file)
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -518,12 +518,20 @@ again:
        }
 
        /*
-        * We need to take care of a possible races here. In fact, the
-        * task might have changed its scheduling policy to something
-        * different from SCHED_DEADLINE or changed its reservation
-        * parameters (through sched_setattr()).
+        * We need to take care of several possible races here:
+        *
+        *   - the task might have changed its scheduling policy
+        *     to something different than SCHED_DEADLINE
+        *   - the task might have changed its reservation parameters
+        *     (through sched_setattr())
+        *   - the task might have been boosted by someone else and
+        *     might be in the boosting/deboosting path
+        *
+        * In all this cases we bail out, as the task is already
+        * in the runqueue or is going to be enqueued back anyway.
         */
-       if (!dl_task(p) || dl_se->dl_new)
+       if (!dl_task(p) || dl_se->dl_new ||
+           dl_se->dl_boosted || !dl_se->dl_throttled)
                goto unlock;
 
        sched_clock_tick();