regulator: core: Make locks re-entrant
Setting voltage, enabling/disabling regulators requires operations on
all regulators related with the regulator being changed. Therefore,
all of them should be locked for the whole operation. With the current
locking implementation, adding additional dependency (regulators
coupling) causes deadlocks in some cases.
Introduce a possibility to attempt to lock a mutex multiple times
by the same task without waiting on a mutex. This should handle all
reasonable coupling-supplying combinations, especially when two coupled
regulators share common supplies. The only situation that should be
forbidden is simultaneous coupling and supplying between a pair of
regulators.
The idea is based on clk core.
Signed-off-by: Maciej Purski <m.purski@samsung.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index fe314ff..0ca941b 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -147,6 +147,56 @@
}
/**
+ * regulator_lock_nested - lock a single regulator
+ * @rdev: regulator source
+ * @subclass: mutex subclass used for lockdep
+ *
+ * This function can be called many times by one task on
+ * a single regulator and its mutex will be locked only
+ * once. If a task, which is calling this function is other
+ * than the one, which initially locked the mutex, it will
+ * wait on mutex.
+ */
+static void regulator_lock_nested(struct regulator_dev *rdev,
+ unsigned int subclass)
+{
+ if (!mutex_trylock(&rdev->mutex)) {
+ if (rdev->mutex_owner == current) {
+ rdev->ref_cnt++;
+ return;
+ }
+ mutex_lock_nested(&rdev->mutex, subclass);
+ }
+
+ rdev->ref_cnt = 1;
+ rdev->mutex_owner = current;
+}
+
+static inline void regulator_lock(struct regulator_dev *rdev)
+{
+ regulator_lock_nested(rdev, 0);
+}
+
+/**
+ * regulator_unlock - unlock a single regulator
+ * @rdev: regulator_source
+ *
+ * This function unlocks the mutex when the
+ * reference counter reaches 0.
+ */
+static void regulator_unlock(struct regulator_dev *rdev)
+{
+ if (rdev->ref_cnt != 0) {
+ rdev->ref_cnt--;
+
+ if (!rdev->ref_cnt) {
+ rdev->mutex_owner = NULL;
+ mutex_unlock(&rdev->mutex);
+ }
+ }
+}
+
+/**
* regulator_lock_supply - lock a regulator and its supplies
* @rdev: regulator source
*/
@@ -155,7 +205,7 @@
int i;
for (i = 0; rdev; rdev = rdev_get_supply(rdev), i++)
- mutex_lock_nested(&rdev->mutex, i);
+ regulator_lock_nested(rdev, i);
}
/**
@@ -167,7 +217,7 @@
struct regulator *supply;
while (1) {
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
supply = rdev->supply;
if (!rdev->supply)
@@ -350,9 +400,9 @@
struct regulator_dev *rdev = dev_get_drvdata(dev);
ssize_t ret;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
ret = sprintf(buf, "%d\n", _regulator_get_voltage(rdev));
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
@@ -416,9 +466,9 @@
struct regulator_dev *rdev = dev_get_drvdata(dev);
ssize_t ret;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
ret = regulator_print_state(buf, _regulator_is_enabled(rdev));
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
@@ -526,10 +576,10 @@
struct regulator *regulator;
int uA = 0;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
list_for_each_entry(regulator, &rdev->consumer_list, list)
uA += regulator->uA_load;
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return sprintf(buf, "%d\n", uA);
}
static DEVICE_ATTR(requested_microamps, 0444, regulator_total_uA_show, NULL);
@@ -1333,7 +1383,7 @@
if (regulator == NULL)
return NULL;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
regulator->rdev = rdev;
list_add(®ulator->list, &rdev->consumer_list);
@@ -1388,12 +1438,12 @@
_regulator_is_enabled(rdev))
regulator->always_on = true;
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return regulator;
overflow_err:
list_del(®ulator->list);
kfree(regulator);
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return NULL;
}
@@ -1782,13 +1832,13 @@
/* remove any sysfs entries */
if (regulator->dev)
sysfs_remove_link(&rdev->dev.kobj, regulator->supply_name);
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
list_del(®ulator->list);
rdev->open_count--;
rdev->exclusive = 0;
put_device(&rdev->dev);
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
kfree_const(regulator->supply_name);
kfree(regulator);
@@ -2396,7 +2446,7 @@
disable_work.work);
int count, i, ret;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
BUG_ON(!rdev->deferred_disables);
@@ -2417,7 +2467,7 @@
rdev_err(rdev, "Deferred disable failed: %d\n", ret);
}
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
if (rdev->supply) {
for (i = 0; i < count; i++) {
@@ -2452,11 +2502,11 @@
if (!ms)
return regulator_disable(regulator);
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
rdev->deferred_disables++;
mod_delayed_work(system_power_efficient_wq, &rdev->disable_work,
msecs_to_jiffies(ms));
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return 0;
}
@@ -2488,10 +2538,10 @@
if (selector >= rdev->desc->n_voltages)
return -EINVAL;
if (lock)
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
ret = ops->list_voltage(rdev, selector);
if (lock)
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
} else if (rdev->is_switch && rdev->supply) {
ret = _regulator_list_voltage(rdev->supply->rdev,
selector, lock);
@@ -3264,7 +3314,7 @@
struct regulator_voltage *voltage = ®ulator->voltage[PM_SUSPEND_ON];
int ret, min_uV, max_uV;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
if (!rdev->desc->ops->set_voltage &&
!rdev->desc->ops->set_voltage_sel) {
@@ -3293,7 +3343,7 @@
ret = _regulator_do_set_voltage(rdev, min_uV, max_uV);
out:
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
EXPORT_SYMBOL_GPL(regulator_sync_voltage);
@@ -3386,7 +3436,7 @@
struct regulator_dev *rdev = regulator->rdev;
int ret;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
/* sanity check */
if (!rdev->desc->ops->set_current_limit) {
@@ -3401,7 +3451,7 @@
ret = rdev->desc->ops->set_current_limit(rdev, min_uA, max_uA);
out:
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
EXPORT_SYMBOL_GPL(regulator_set_current_limit);
@@ -3410,7 +3460,7 @@
{
int ret;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
/* sanity check */
if (!rdev->desc->ops->get_current_limit) {
@@ -3420,7 +3470,7 @@
ret = rdev->desc->ops->get_current_limit(rdev);
out:
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
@@ -3456,7 +3506,7 @@
int ret;
int regulator_curr_mode;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
/* sanity check */
if (!rdev->desc->ops->set_mode) {
@@ -3480,7 +3530,7 @@
ret = rdev->desc->ops->set_mode(rdev, mode);
out:
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
EXPORT_SYMBOL_GPL(regulator_set_mode);
@@ -3489,7 +3539,7 @@
{
int ret;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
/* sanity check */
if (!rdev->desc->ops->get_mode) {
@@ -3499,7 +3549,7 @@
ret = rdev->desc->ops->get_mode(rdev);
out:
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
@@ -3520,7 +3570,7 @@
{
int ret;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
/* sanity check */
if (!rdev->desc->ops->get_error_flags) {
@@ -3530,7 +3580,7 @@
ret = rdev->desc->ops->get_error_flags(rdev, flags);
out:
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
@@ -3579,10 +3629,10 @@
struct regulator_dev *rdev = regulator->rdev;
int ret;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
regulator->uA_load = uA_load;
ret = drms_uA_update(rdev);
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
@@ -3610,7 +3660,7 @@
if (!regulator_ops_is_valid(rdev, REGULATOR_CHANGE_BYPASS))
return 0;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
if (enable && !regulator->bypass) {
rdev->bypass_count++;
@@ -3634,7 +3684,7 @@
if (ret == 0)
regulator->bypass = enable;
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
@@ -4300,9 +4350,9 @@
suspend_state_t *state = data;
int ret;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
ret = suspend_set_state(rdev, *state);
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
@@ -4332,14 +4382,14 @@
if (rstate == NULL)
return 0;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
if (rdev->desc->ops->resume_early &&
(rstate->enabled == ENABLE_IN_SUSPEND ||
rstate->enabled == DISABLE_IN_SUSPEND))
ret = rdev->desc->ops->resume_early(rdev);
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return ret;
}
@@ -4641,7 +4691,7 @@
if (!regulator_ops_is_valid(rdev, REGULATOR_CHANGE_STATUS))
return 0;
- mutex_lock(&rdev->mutex);
+ regulator_lock(rdev);
if (rdev->use_count)
goto unlock;
@@ -4672,7 +4722,7 @@
}
unlock:
- mutex_unlock(&rdev->mutex);
+ regulator_unlock(rdev);
return 0;
}
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 14e512a..c2a181f 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -434,6 +434,8 @@
struct blocking_notifier_head notifier;
struct mutex mutex; /* consumer lock */
+ struct task_struct *mutex_owner;
+ int ref_cnt;
struct module *owner;
struct device dev;
struct regulation_constraints *constraints;