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pwm: Don't check pointer for being non-NULL after use 

After assigning chip = pwm->chip; the compiler is free to assume that
pwm is non-NULL and so can optimize out the check for pwm against NULL.

While it's probably a programming error to pass a NULL pointer to
pwm_put() this shouldn't be dropped without careful consideration and
wasn't intended.

So assign chip only after the NULL check.

Reported-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/66a6f562-1fdd-4e45-995a-e7995432aa0c@baylibre.com
Fixes: 4c56b1434b ("pwm: Add a struct device to struct pwm_chip")
Link: https://lore.kernel.org/r/20240329101648.544155-2-u.kleine-koenig@pengutronix.de
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
This commit is contained in:
Uwe Kleine-König 2024-03-29 11:07:56 +01:00
parent 4c56b1434b
commit c6837aa180
1 changed files with 3 additions and 1 deletions
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4
drivers/pwm/core.c
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@ -1525,11 +1525,13 @@ EXPORT_SYMBOL_GPL(pwm_get);
*/
void pwm_put(struct pwm_device *pwm)
{
struct pwm_chip *chip = pwm->chip;
struct pwm_chip *chip;
if (!pwm)
return;
chip = pwm->chip;
mutex_lock(&pwm_lock);
if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) {