This is a note to let you know that I've just added the patch titled pwm: sifive: Call pwm_sifive_update_clock() while mutex is held to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: pwm-sifive-call-pwm_sifive_update_clock-while-mutex-.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 53c04d4a466308001e998a1bc60a9c56f349a78b Author: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> Date: Fri Dec 2 19:35:05 2022 +0100 pwm: sifive: Call pwm_sifive_update_clock() while mutex is held [ Upstream commit 45558b3abb87eeb2cedb8a59cb2699c120b5102a ] As was documented in commit 0f02f491b786 ("pwm: sifive: Reduce time the controller lock is held") a caller of pwm_sifive_update_clock() must hold the mutex. So fix pwm_sifive_clock_notifier() to grab the lock. While this necessity was only documented later, the race exists since the driver was introduced. Fixes: 9e37a53eb051 ("pwm: sifive: Add a driver for SiFive SoC PWM") Reported-by: Emil Renner Berthing <emil.renner.berthing@xxxxxxxxxxxxx> Reviewed-by: Emil Renner Berthing <emil.renner.berthing@xxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20221018061656.1428111-1-u.kleine-koenig@xxxxxxxxxxxxxx Signed-off-by: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> Signed-off-by: Thierry Reding <thierry.reding@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c index cc63f9baa481..538297ef8255 100644 --- a/drivers/pwm/pwm-sifive.c +++ b/drivers/pwm/pwm-sifive.c @@ -221,8 +221,11 @@ static int pwm_sifive_clock_notifier(struct notifier_block *nb, struct pwm_sifive_ddata *ddata = container_of(nb, struct pwm_sifive_ddata, notifier); - if (event == POST_RATE_CHANGE) + if (event == POST_RATE_CHANGE) { + mutex_lock(&ddata->lock); pwm_sifive_update_clock(ddata, ndata->new_rate); + mutex_unlock(&ddata->lock); + } return NOTIFY_OK; }