From 459a25afe97cb3d7f978b90c881f4d7aac8fb755 Mon Sep 17 00:00:00 2001 From: Boris BREZILLON Date: Wed, 30 Mar 2016 22:03:27 +0200 Subject: pwm: Get rid of pwm->lock PWM devices are not protected against concurrent accesses. The lock in struct pwm_device might let PWM users think it is, but it's actually only protecting the enabled state. Removing this lock should be fine as long as all PWM users are aware that accesses to the PWM device have to be serialized, which seems to be the case for all of them except the sysfs interface. Patch the sysfs code by adding a lock to the pwm_export struct and making sure it's taken for all relevant accesses to the exported PWM device. Signed-off-by: Boris Brezillon Signed-off-by: Thierry Reding --- drivers/pwm/core.c | 19 ++++--------------- 1 file changed, 4 insertions(+), 15 deletions(-) (limited to 'drivers/pwm/core.c') diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c index 22cf3959041c..cb762cf51332 100644 --- a/drivers/pwm/core.c +++ b/drivers/pwm/core.c @@ -269,7 +269,6 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip, pwm->pwm = chip->base + i; pwm->hwpwm = i; pwm->polarity = polarity; - mutex_init(&pwm->lock); radix_tree_insert(&pwm_tree, pwm->pwm, pwm); } @@ -474,22 +473,16 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity) if (!pwm->chip->ops->set_polarity) return -ENOSYS; - mutex_lock(&pwm->lock); - - if (pwm_is_enabled(pwm)) { - err = -EBUSY; - goto unlock; - } + if (pwm_is_enabled(pwm)) + return -EBUSY; err = pwm->chip->ops->set_polarity(pwm->chip, pwm, polarity); if (err) - goto unlock; + return err; pwm->polarity = polarity; -unlock: - mutex_unlock(&pwm->lock); - return err; + return 0; } EXPORT_SYMBOL_GPL(pwm_set_polarity); @@ -506,16 +499,12 @@ int pwm_enable(struct pwm_device *pwm) if (!pwm) return -EINVAL; - mutex_lock(&pwm->lock); - if (!test_and_set_bit(PWMF_ENABLED, &pwm->flags)) { err = pwm->chip->ops->enable(pwm->chip, pwm); if (err) clear_bit(PWMF_ENABLED, &pwm->flags); } - mutex_unlock(&pwm->lock); - return err; } EXPORT_SYMBOL_GPL(pwm_enable); -- cgit v1.2.3