From: Uwe Kleine-König u.kleine-koenig@pengutronix.de
[ 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@canonical.com Reviewed-by: Emil Renner Berthing emil.renner.berthing@canonical.com Link: https://lore.kernel.org/r/20221018061656.1428111-1-u.kleine-koenig@pengutron... Signed-off-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de Signed-off-by: Thierry Reding thierry.reding@gmail.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/pwm/pwm-sifive.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c index 2d4fa5e5fdd4..bb7239313401 100644 --- a/drivers/pwm/pwm-sifive.c +++ b/drivers/pwm/pwm-sifive.c @@ -204,8 +204,11 @@ 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; }