From: Jassi Brar jaswinder.singh@linaro.org
[ Upstream commit c7dacf5b0f32957b24ef29df1207dc2cd8307743 ]
If the txdone is done by polling, it is possible for msg_submit() to start the timer while txdone_hrtimer() callback is running. If the timer needs recheduling, it could already be enqueued by the time hrtimer_forward_now() is called, leading hrtimer to loudly complain.
WARNING: CPU: 3 PID: 74 at kernel/time/hrtimer.c:932 hrtimer_forward+0xc4/0x110 CPU: 3 PID: 74 Comm: kworker/u8:1 Not tainted 5.9.0-rc2-00236-gd3520067d01c-dirty #5 Hardware name: Libre Computer AML-S805X-AC (DT) Workqueue: events_freezable_power_ thermal_zone_device_check pstate: 20000085 (nzCv daIf -PAN -UAO BTYPE=--) pc : hrtimer_forward+0xc4/0x110 lr : txdone_hrtimer+0xf8/0x118 [...]
This can be fixed by not starting the timer from the callback path. Which requires the timer reloading as long as any message is queued on the channel, and not just when current tx is not done yet.
Fixes: 0cc67945ea59 ("mailbox: switch to hrtimer for tx_complete polling") Reported-by: Da Xue da@libre.computer Reviewed-by: Sudeep Holla sudeep.holla@arm.com Tested-by: Sudeep Holla sudeep.holla@arm.com Acked-by: Jerome Brunet jbrunet@baylibre.com Tested-by: Jerome Brunet jbrunet@baylibre.com Signed-off-by: Jassi Brar jaswinder.singh@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/mailbox/mailbox.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c index 055c90b8253cb..10a559cfb7ea3 100644 --- a/drivers/mailbox/mailbox.c +++ b/drivers/mailbox/mailbox.c @@ -85,9 +85,12 @@ static void msg_submit(struct mbox_chan *chan) exit: spin_unlock_irqrestore(&chan->lock, flags);
- if (!err && (chan->txdone_method & TXDONE_BY_POLL)) - /* kick start the timer immediately to avoid delays */ - hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL); + /* kick start the timer immediately to avoid delays */ + if (!err && (chan->txdone_method & TXDONE_BY_POLL)) { + /* but only if not already active */ + if (!hrtimer_active(&chan->mbox->poll_hrt)) + hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL); + } }
static void tx_tick(struct mbox_chan *chan, int r) @@ -125,11 +128,10 @@ static enum hrtimer_restart txdone_hrtimer(struct hrtimer *hrtimer) struct mbox_chan *chan = &mbox->chans[i];
if (chan->active_req && chan->cl) { + resched = true; txdone = chan->mbox->ops->last_tx_done(chan); if (txdone) tx_tick(chan, 0); - else - resched = true; } }