From: Jerome Brunet <jbrunet@baylibre.com>
To: Jassi Brar <jassisinghbrar@gmail.com>
Cc: Jerome Brunet <jbrunet@baylibre.com>,
Kevin Hilman <khilman@baylibre.com>,
linux-amlogic@lists.infradead.org, linux-kernel@vger.kernel.org,
Da Xue <da@libre.computer>
Subject: [PATCH] mailbox: cancel timer before starting it
Date: Wed, 23 Sep 2020 14:39:16 +0200 [thread overview]
Message-ID: <20200923123916.1115962-1-jbrunet@baylibre.com> (raw)
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
[...]
Canceling the timer before starting it ensure that the timer callback is
not running when the timer is started, solving this race condition.
Fixes: 0cc67945ea59 ("mailbox: switch to hrtimer for tx_complete polling")
Reported-by: Da Xue <da@libre.computer>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
---
drivers/mailbox/mailbox.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
index 0b821a5b2db8..34f9ab01caef 100644
--- a/drivers/mailbox/mailbox.c
+++ b/drivers/mailbox/mailbox.c
@@ -82,9 +82,13 @@ 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 */
+ if (!err && (chan->txdone_method & TXDONE_BY_POLL)) {
+ /* Disable the timer if already active ... */
+ hrtimer_cancel(&chan->mbox->poll_hrt);
+
+ /* ... and kick start it immediately to avoid delays */
hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
+ }
}
static void tx_tick(struct mbox_chan *chan, int r)
--
2.25.4
next reply other threads:[~2020-09-23 12:39 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-23 12:39 Jerome Brunet [this message]
2020-09-24 16:50 ` [PATCH] mailbox: cancel timer before starting it Kevin Hilman
2020-10-15 13:46 ` Ionela Voinescu
2020-10-15 13:58 ` Jerome Brunet
2020-10-15 14:29 ` Ionela Voinescu
2020-10-16 8:44 ` Sudeep Holla
2020-10-16 9:02 ` Jerome Brunet
2020-10-16 9:34 ` Sudeep Holla
2020-10-16 11:47 ` Sudeep Holla
2020-10-15 18:45 ` Jassi Brar
2020-10-16 8:52 ` Ionela Voinescu
2020-10-16 9:00 ` Jerome Brunet
2020-10-16 13:52 ` Sudeep Holla
2020-10-16 17:33 ` Jassi Brar
2020-10-16 18:54 ` Jerome Brunet
2020-10-16 19:27 ` Jassi Brar
2022-07-19 7:08 ` Da Xue
2020-10-16 11:52 ` Sudeep Holla
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200923123916.1115962-1-jbrunet@baylibre.com \
--to=jbrunet@baylibre.com \
--cc=da@libre.computer \
--cc=jassisinghbrar@gmail.com \
--cc=khilman@baylibre.com \
--cc=linux-amlogic@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).