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authorUwe Kleine-König <u.kleine-koenig@pengutronix.de>2024-03-17 11:40:35 +0100
committerUwe Kleine-König <u.kleine-koenig@pengutronix.de>2024-04-26 21:29:17 +0200
commitee37bf50749f06b29394d7ba8a85b47f023b61e2 (patch)
tree061cf6f9a5e533c464ff1aa26373487494e1126c /drivers/pwm/core.c
parente9cc807f87ffd1ccc919731e8f624982935af3e0 (diff)
pwm: Ensure a struct pwm has the same lifetime as its pwm_chip
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 <gustavoars@kernel.org> # 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 <u.kleine-koenig@pengutronix.de>
Diffstat (limited to 'drivers/pwm/core.c')
-rw-r--r--drivers/pwm/core.c27
1 files changed, 10 insertions, 17 deletions
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);