linux-kernel - [PATCH 3.2 129/199] can: bcm: fix hrtimer/tasklet termination in bcm op removal

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Message-ID: <lsq.1489146370.433626226@decadent.org.uk>
Date:   Fri, 10 Mar 2017 11:46:10 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Oliver Hartkopp" <socketcan@...tkopp.net>,
        "Michael Josenhans" <michael.josenhans@....de>,
        "Marc Kleine-Budde" <mkl@...gutronix.de>
Subject: [PATCH 3.2 129/199] can: bcm: fix hrtimer/tasklet termination in
 bcm op removal

3.2.87-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Oliver Hartkopp <socketcan@...tkopp.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.josenhans@....de>
Signed-off-by: Oliver Hartkopp <socketcan@...tkopp.net>
Tested-by: Michael Josenhans <michael.josenhans@....de>
Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/can/bcm.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -702,14 +702,23 @@ 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);