4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Oliver Hartkopp <socket...@hartkopp.net>

commit a06393ed03167771246c4c43192d9c264bc48412 upstream.

When removing a bcm tx operation either a hrtimer or a tasklet might run.
As the hrtimer triggers its associated tasklet and vice versa we need to
take care to mutually terminate both handlers.

Reported-by: Michael Josenhans <michael.josenh...@web.de>
Signed-off-by: Oliver Hartkopp <socket...@hartkopp.net>
Tested-by: Michael Josenhans <michael.josenh...@web.de>
Signed-off-by: Marc Kleine-Budde <m...@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 net/can/bcm.c |   23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -734,14 +734,23 @@ static struct bcm_op *bcm_find_op(struct
 
 static void bcm_remove_op(struct bcm_op *op)
 {
-       hrtimer_cancel(&op->timer);
-       hrtimer_cancel(&op->thrtimer);
+       if (op->tsklet.func) {
+               while (test_bit(TASKLET_STATE_SCHED, &op->tsklet.state) ||
+                      test_bit(TASKLET_STATE_RUN, &op->tsklet.state) ||
+                      hrtimer_active(&op->timer)) {
+                       hrtimer_cancel(&op->timer);
+                       tasklet_kill(&op->tsklet);
+               }
+       }
 
-       if (op->tsklet.func)
-               tasklet_kill(&op->tsklet);
-
-       if (op->thrtsklet.func)
-               tasklet_kill(&op->thrtsklet);
+       if (op->thrtsklet.func) {
+               while (test_bit(TASKLET_STATE_SCHED, &op->thrtsklet.state) ||
+                      test_bit(TASKLET_STATE_RUN, &op->thrtsklet.state) ||
+                      hrtimer_active(&op->thrtimer)) {
+                       hrtimer_cancel(&op->thrtimer);
+                       tasklet_kill(&op->thrtsklet);
+               }
+       }
 
        if ((op->frames) && (op->frames != &op->sframe))
                kfree(op->frames);


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