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pwm: sifive: Call pwm_sifive_update_clock() while mutex is held

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[ 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: 9e37a53eb0 ("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@pengutronix.de
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>
This commit is contained in:
Uwe Kleine-König 2022-12-02 19:35:05 +01:00 committed by Greg Kroah-Hartman
parent 2b7ad43574
commit 292c0f3b4a
1 changed files with 4 additions and 1 deletions
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5
drivers/pwm/pwm-sifive.c
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@ -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;
}