From ee37bf50749f06b29394d7ba8a85b47f023b61e2 Mon Sep 17 00:00:00 2001 From: Uwe Kleine-König Date: Sun, 17 Mar 2024 11:40:35 +0100 Subject: pwm: Ensure a struct pwm has the same lifetime as its pwm_chip MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit It's required to not free the memory underlying a requested PWM while a consumer still has a reference to it. While currently a pwm_chip doesn't live long enough in all cases, linking the struct pwm to the pwm_chip results in the right lifetime as soon as the pwmchip is living long enough. This happens with the following commits. Note this is a breaking change for all pwm drivers that don't use pwmchip_alloc(). Reviewed-by: Gustavo A. R. Silva # for struct_size() and __counted_by() Link: https://lore.kernel.org/r/7e9e958841f049026c0023b309cc9deecf0ab61d.1710670958.git.u.kleine-koenig@pengutronix.de Signed-off-by: Uwe Kleine-König --- drivers/pwm/core.c | 27 ++++++++++----------------- 1 file changed, 10 insertions(+), 17 deletions(-) (limited to 'drivers/pwm') diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index faa0f885e057..19386452e6c8 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -987,7 +987,7 @@ static void pwmchip_sysfs_unexport(struct pwm_chip *chip) static void *pwmchip_priv(struct pwm_chip *chip) { - return (void *)chip + ALIGN(sizeof(*chip), PWMCHIP_ALIGN); + return (void *)chip + ALIGN(struct_size(chip, pwms, chip->npwm), PWMCHIP_ALIGN); } /* This is the counterpart to pwmchip_alloc() */ @@ -1001,8 +1001,10 @@ struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t { struct pwm_chip *chip; size_t alloc_size; + unsigned int i; - alloc_size = size_add(ALIGN(sizeof(*chip), PWMCHIP_ALIGN), sizeof_priv); + alloc_size = size_add(ALIGN(struct_size(chip, pwms, npwm), PWMCHIP_ALIGN), + sizeof_priv); chip = kzalloc(alloc_size, GFP_KERNEL); if (!chip) @@ -1014,6 +1016,12 @@ struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t pwmchip_set_drvdata(chip, pwmchip_priv(chip)); + for (i = 0; i < chip->npwm; i++) { + struct pwm_device *pwm = &chip->pwms[i]; + pwm->chip = chip; + pwm->hwpwm = i; + } + return chip; } EXPORT_SYMBOL_GPL(pwmchip_alloc); @@ -1085,7 +1093,6 @@ static bool pwm_ops_check(const struct pwm_chip *chip) */ int __pwmchip_add(struct pwm_chip *chip, struct module *owner) { - unsigned int i; int ret; if (!chip || !pwmchip_parent(chip) || !chip->ops || !chip->npwm) @@ -1105,28 +1112,16 @@ int __pwmchip_add(struct pwm_chip *chip, struct module *owner) chip->owner = owner; - chip->pwms = kcalloc(chip->npwm, sizeof(*chip->pwms), GFP_KERNEL); - if (!chip->pwms) - return -ENOMEM; - mutex_lock(&pwm_lock); ret = idr_alloc(&pwm_chips, chip, 0, 0, GFP_KERNEL); if (ret < 0) { mutex_unlock(&pwm_lock); - kfree(chip->pwms); return ret; } chip->id = ret; - for (i = 0; i < chip->npwm; i++) { - struct pwm_device *pwm = &chip->pwms[i]; - - pwm->chip = chip; - pwm->hwpwm = i; - } - mutex_unlock(&pwm_lock); if (IS_ENABLED(CONFIG_OF)) @@ -1156,8 +1151,6 @@ void pwmchip_remove(struct pwm_chip *chip) idr_remove(&pwm_chips, chip->id); mutex_unlock(&pwm_lock); - - kfree(chip->pwms); } EXPORT_SYMBOL_GPL(pwmchip_remove); -- cgit v1.2.3-70-g09d2