The introduction of the mutex in commit d1cd21427747 ("pwm: Set enable
state properly on failed call to enable") effectively makes all PWM drivers
potentially sleeping. That in turn makes the .can_sleep field obsolete
since all drivers can now sleep.
Changes fix the below bug by using spinlocks instead of mutex
[ 22.300239] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:97
[ 22.307212] in_atomic(): 1, irqs_disabled(): 0, pid: 2257, name: sh
[ 22.313454] Preemption disabled at:[< (null)>] (null)
[ 23.655232] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:97
[ 23.662174] in_atomic(): 1, irqs_disabled(): 0, pid: 2404, name: upowerd
[ 23.668932] Preemption disabled at:[< (null)>] (null)
[ 25.010207] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:97
[ 25.017125] in_atomic(): 1, irqs_disabled(): 0, pid: 2262, name: indicator-keybo
[ 25.024491] Preemption disabled at:[< (null)>] (null)
[ 26.355237] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:97
[ 26.362141] in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper/0
[ 26.368728] Preemption disabled at:[< (null)>] (null)
[ 27.680220] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:97
[ 27.687119] in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper/0
[ 27.693698] Preemption disabled at:[< (null)>] (null)
[ 29.005199] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:97
[ 29.012124] in_atomic(): 1, irqs_disabled(): 0, pid: 0, name: swapper/0
[thierry.reding@xxxxxxxxx: Fixed the commit message]
Signed-off-by: Anand Moon <linux.amoon@xxxxxxxxx>
---
Changes logs: droped my prevoius approch.
---
drivers/pwm/core.c | 10 +++++-----
include/linux/pwm.h | 4 ++--
2 files changed, 7 insertions(+), 7 deletions(-)
diff --git a/drivers/pwm/core.c b/drivers/pwm/core.c
index d24ca5f..58e7091 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -269,7 +269,7 @@ int pwmchip_add_with_polarity(struct pwm_chip *chip,
pwm->pwm = chip->base + i;
pwm->hwpwm = i;
pwm->polarity = polarity;
- mutex_init(&pwm->lock);
+ spin_lock_init(&pwm->lock);
radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
}
@@ -474,7 +474,7 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
if (!pwm->chip->ops->set_polarity)
return -ENOSYS;
- mutex_lock(&pwm->lock);
+ spin_lock_irq(&pwm->lock);
if (pwm_is_enabled(pwm)) {
err = -EBUSY;
@@ -488,7 +488,7 @@ int pwm_set_polarity(struct pwm_device *pwm, enum pwm_polarity polarity)
pwm->polarity = polarity;
unlock:
- mutex_unlock(&pwm->lock);
+ spin_unlock_irq(&pwm->lock);
return err;
}
EXPORT_SYMBOL_GPL(pwm_set_polarity);
@@ -506,7 +506,7 @@ int pwm_enable(struct pwm_device *pwm)
if (!pwm)
return -EINVAL;
- mutex_lock(&pwm->lock);
+ spin_lock_irq(&pwm->lock);
if (!test_and_set_bit(PWMF_ENABLED, &pwm->flags)) {
err = pwm->chip->ops->enable(pwm->chip, pwm);
@@ -514,7 +514,7 @@ int pwm_enable(struct pwm_device *pwm)
clear_bit(PWMF_ENABLED, &pwm->flags);
}
- mutex_unlock(&pwm->lock);
+ spin_unlock_irq(&pwm->lock);
return err;
}
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index cfc3ed4..86ad4c2 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -2,7 +2,7 @@
#define __LINUX_PWM_H
#include <linux/err.h>
-#include <linux/mutex.h>
+#include <linux/spinlock.h>
#include <linux/of.h>
struct pwm_device;
@@ -100,7 +100,7 @@ struct pwm_device {
unsigned int pwm;
struct pwm_chip *chip;
void *chip_data;
- struct mutex lock;
+ spinlock_t lock;
unsigned int period;
unsigned int duty_cycle;
--
2.1.4
--
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