Wait/wound mutex shall be used in order to avoid lockups on locking of
coupled regulators.
Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
Suggested-by: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
---
drivers/regulator/core.c | 401 +++++++++++++++++++++++--------
include/linux/regulator/driver.h | 3 +-
2 files changed, 307 insertions(+), 97 deletions(-)
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 783ec9c74104..a3448636f334 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -50,6 +50,8 @@
#define rdev_dbg(rdev, fmt, ...) \
pr_debug("%s: " fmt, rdev_get_name(rdev), ##__VA_ARGS__)
+static DEFINE_WW_CLASS(regulator_ww_class);
+static DEFINE_MUTEX(regulator_nesting_mutex);
static DEFINE_MUTEX(regulator_list_mutex);
static LIST_HEAD(regulator_map_list);
static LIST_HEAD(regulator_ena_gpio_list);
@@ -154,7 +156,7 @@ static inline struct regulator_dev *rdev_get_supply(struct regulator_dev *rdev)
/**
* regulator_lock_nested - lock a single regulator
* @rdev: regulator source
- * @subclass: mutex subclass used for lockdep
+ * @ww_ctx: w/w mutex acquire context
*
* This function can be called many times by one task on
* a single regulator and its mutex will be locked only
@@ -162,24 +164,52 @@ static inline struct regulator_dev *rdev_get_supply(struct regulator_dev *rdev)
* 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)
+static inline int regulator_lock_nested(struct regulator_dev *rdev,
+ struct ww_acquire_ctx *ww_ctx)
{
- if (!mutex_trylock(&rdev->mutex)) {
- if (rdev->mutex_owner == current) {
+ bool lock = false;
+ int ret = 0;
+
+ mutex_lock(®ulator_nesting_mutex);
+
+ if (ww_ctx || !ww_mutex_trylock(&rdev->mutex)) {
+ if (rdev->mutex_owner == current)
rdev->ref_cnt++;
- return;
+ else
+ lock = true;
+
+ if (lock) {
+ mutex_unlock(®ulator_nesting_mutex);
+ ret = ww_mutex_lock(&rdev->mutex, ww_ctx);
+ mutex_lock(®ulator_nesting_mutex);
}
- mutex_lock_nested(&rdev->mutex, subclass);
+ } else {
+ lock = true;
}
- rdev->ref_cnt = 1;
- rdev->mutex_owner = current;
+ if (lock && ret != -EDEADLK) {
+ rdev->ref_cnt++;
+ rdev->mutex_owner = current;
+ }
+
+ mutex_unlock(®ulator_nesting_mutex);
+
+ return ret;
}
-static inline void regulator_lock(struct regulator_dev *rdev)
+/**
+ * regulator_lock - lock a single regulator
+ * @rdev: regulator source
+ *
+ * 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(struct regulator_dev *rdev)
{
- regulator_lock_nested(rdev, 0);
+ regulator_lock_nested(rdev, NULL);
}
/**
@@ -191,50 +221,46 @@ static inline void regulator_lock(struct regulator_dev *rdev)
*/
static void regulator_unlock(struct regulator_dev *rdev)
{
- if (rdev->ref_cnt != 0) {
- rdev->ref_cnt--;
+ mutex_lock(®ulator_nesting_mutex);
- if (!rdev->ref_cnt) {
- rdev->mutex_owner = NULL;
- mutex_unlock(&rdev->mutex);
- }
+ if (--rdev->ref_cnt == 0) {
+ rdev->mutex_owner = NULL;
+ ww_mutex_unlock(&rdev->mutex);
}
+
+ WARN_ON_ONCE(rdev->ref_cnt < 0);
+
+ mutex_unlock(®ulator_nesting_mutex);
}
-static int regulator_lock_recursive(struct regulator_dev *rdev,
- unsigned int subclass)
+static void regulator_unlock_recursive(struct regulator_dev *rdev,
+ unsigned int n_coupled)
{
struct regulator_dev *c_rdev;
int i;
- for (i = 0; i < rdev->coupling_desc.n_coupled; i++) {
- c_rdev = rdev->coupling_desc.coupled_rdevs[i];
+ for (i = n_coupled; i > 0; i--) {
+ c_rdev = rdev->coupling_desc.coupled_rdevs[i - 1];
if (!c_rdev)
continue;
- regulator_lock_nested(c_rdev, subclass++);
-
if (c_rdev->supply)
- subclass =
- regulator_lock_recursive(c_rdev->supply->rdev,
- subclass);
- }
+ regulator_unlock_recursive(
+ c_rdev->supply->rdev,
+ c_rdev->coupling_desc.n_coupled);
- return subclass;
+ regulator_unlock(c_rdev);
+ }
}
-/**
- * regulator_unlock_dependent - unlock regulator's suppliers and coupled
- * regulators
- * @rdev: regulator source
- *
- * Unlock all regulators related with rdev by coupling or suppling.
- */
-static void regulator_unlock_dependent(struct regulator_dev *rdev)
+static int regulator_lock_recursive(struct regulator_dev *rdev,
+ struct regulator_dev **new_contended_rdev,
+ struct regulator_dev **old_contended_rdev,
+ struct ww_acquire_ctx *ww_ctx)
{
struct regulator_dev *c_rdev;
- int i;
+ int i, err;
for (i = 0; i < rdev->coupling_desc.n_coupled; i++) {
c_rdev = rdev->coupling_desc.coupled_rdevs[i];
@@ -242,23 +268,95 @@ static void regulator_unlock_dependent(struct regulator_dev *rdev)
if (!c_rdev)
continue;
- regulator_unlock(c_rdev);
+ if (c_rdev != *old_contended_rdev) {
+ err = regulator_lock_nested(c_rdev, ww_ctx);
+ if (err) {
+ if (err == -EDEADLK) {
+ *new_contended_rdev = c_rdev;
+ goto err_unlock;
+ }
- if (c_rdev->supply)
- regulator_unlock_dependent(c_rdev->supply->rdev);
+ /* shouldn't happen */
+ WARN_ON_ONCE(err != -EALREADY);
+ }
+ } else {
+ *old_contended_rdev = NULL;
+ }
+
+ if (c_rdev->supply) {
+ err = regulator_lock_recursive(c_rdev->supply->rdev,
+ new_contended_rdev,
+ old_contended_rdev,
+ ww_ctx);
+ if (err) {
+ regulator_unlock(c_rdev);
+ goto err_unlock;
+ }
+ }
}
+
+ return 0;
+
+err_unlock:
+ regulator_unlock_recursive(rdev, i);
+
+ return err;
+}
+
+/**
+ * regulator_unlock_dependent - unlock regulator's suppliers and coupled
+ * regulators
+ * @rdev: regulator source
+ * @ww_ctx: w/w mutex acquire context
+ *
+ * Unlock all regulators related with rdev by coupling or suppling.
+ */
+static void regulator_unlock_dependent(struct regulator_dev *rdev,
+ struct ww_acquire_ctx *ww_ctx)
+{
+ regulator_unlock_recursive(rdev, rdev->coupling_desc.n_coupled);
+ ww_acquire_fini(ww_ctx);
}
/**
* regulator_lock_dependent - lock regulator's suppliers and coupled regulators
* @rdev: regulator source
+ * @ww_ctx: w/w mutex acquire context
*
* This function as a wrapper on regulator_lock_recursive(), which locks
* all regulators related with rdev by coupling or suppling.
*/
-static inline void regulator_lock_dependent(struct regulator_dev *rdev)
+static void regulator_lock_dependent(struct regulator_dev *rdev,
+ struct ww_acquire_ctx *ww_ctx)
{
- regulator_lock_recursive(rdev, 0);
+ struct regulator_dev *new_contended_rdev = NULL;
+ struct regulator_dev *old_contended_rdev = NULL;
+ int err;
+
+ mutex_lock(®ulator_list_mutex);
+
+ ww_acquire_init(ww_ctx, ®ulator_ww_class);
+
+ do {
+ if (new_contended_rdev) {
+ ww_mutex_lock_slow(&new_contended_rdev->mutex, ww_ctx);
+ old_contended_rdev = new_contended_rdev;
+ old_contended_rdev->ref_cnt++;
+ }
+
+ err = regulator_lock_recursive(rdev,
+ &new_contended_rdev,
+ &old_contended_rdev,
+ ww_ctx);
+
+ if (old_contended_rdev)
+ regulator_unlock(old_contended_rdev);
+
+ } while (err == -EDEADLK);
+
+ ww_acquire_done(ww_ctx);
+
+ mutex_unlock(®ulator_list_mutex);
}
/**
@@ -772,7 +870,7 @@ static int drms_uA_update(struct regulator_dev *rdev)
int current_uA = 0, output_uV, input_uV, err;
unsigned int mode;
- lockdep_assert_held_once(&rdev->mutex);
+ lockdep_assert_held_once(&rdev->mutex.base);
/*
* first check to see if we can set modes at all, otherwise just
@@ -2274,7 +2372,20 @@ static int _regulator_enable(struct regulator_dev *rdev)
{
int ret;
- lockdep_assert_held_once(&rdev->mutex);
+ lockdep_assert_held_once(&rdev->mutex.base);
+
+ if (rdev->supply) {
+ ret = _regulator_enable(rdev->supply->rdev);
+ if (ret < 0)
+ return ret;
+ }
+
+ /* balance only if there are regulators coupled */
+ if (rdev->coupling_desc.n_coupled > 1) {
+ ret = regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+ if (ret < 0)
+ goto err_disable_supply;
+ }
/* check voltage and requested load before enabling */
if (regulator_ops_is_valid(rdev, REGULATOR_CHANGE_DRMS))
@@ -2285,18 +2396,20 @@ static int _regulator_enable(struct regulator_dev *rdev)
ret = _regulator_is_enabled(rdev);
if (ret == -EINVAL || ret == 0) {
if (!regulator_ops_is_valid(rdev,
- REGULATOR_CHANGE_STATUS))
- return -EPERM;
+ REGULATOR_CHANGE_STATUS)) {
+ ret = -EPERM;
+ goto err_disable_supply;
+ }
ret = _regulator_do_enable(rdev);
if (ret < 0)
- return ret;
+ goto err_disable_supply;
_notifier_call_chain(rdev, REGULATOR_EVENT_ENABLE,
NULL);
} else if (ret < 0) {
rdev_err(rdev, "is_enabled() failed: %d\n", ret);
- return ret;
+ goto err_disable_supply;
}
/* Fallthrough on positive return values - already enabled */
}
@@ -2304,6 +2417,12 @@ static int _regulator_enable(struct regulator_dev *rdev)
rdev->use_count++;
return 0;
+
+err_disable_supply:
+ if (rdev->supply)
+ _regulator_disable(rdev->supply->rdev);
+
+ return ret;
}
/**
@@ -2320,30 +2439,15 @@ static int _regulator_enable(struct regulator_dev *rdev)
int regulator_enable(struct regulator *regulator)
{
struct regulator_dev *rdev = regulator->rdev;
+ struct ww_acquire_ctx ww_ctx;
int ret = 0;
if (regulator->always_on)
return 0;
- if (rdev->supply) {
- ret = regulator_enable(rdev->supply);
- if (ret != 0)
- return ret;
- }
-
- regulator_lock_dependent(rdev);
- /* balance only if there are regulators coupled */
- if (rdev->coupling_desc.n_coupled > 1) {
- ret = regulator_balance_voltage(rdev, PM_SUSPEND_ON);
- if (ret != 0)
- goto unlock;
- }
+ regulator_lock_dependent(rdev, &ww_ctx);
ret = _regulator_enable(rdev);
-unlock:
- regulator_unlock_dependent(rdev);
-
- if (ret != 0 && rdev->supply)
- regulator_disable(rdev->supply);
+ regulator_unlock_dependent(rdev, &ww_ctx);
return ret;
}
@@ -2385,7 +2489,7 @@ static int _regulator_disable(struct regulator_dev *rdev)
{
int ret = 0;
- lockdep_assert_held_once(&rdev->mutex);
+ lockdep_assert_held_once(&rdev->mutex.base);
if (WARN(rdev->use_count <= 0,
"unbalanced disables for %s\n", rdev_get_name(rdev)))
@@ -2423,6 +2527,12 @@ static int _regulator_disable(struct regulator_dev *rdev)
rdev->use_count--;
}
+ if (ret == 0 && rdev->coupling_desc.n_coupled > 1)
+ ret = regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+
+ if (ret == 0 && rdev->supply)
+ ret = _regulator_disable(rdev->supply->rdev);
+
return ret;
}
@@ -2441,19 +2551,15 @@ static int _regulator_disable(struct regulator_dev *rdev)
int regulator_disable(struct regulator *regulator)
{
struct regulator_dev *rdev = regulator->rdev;
+ struct ww_acquire_ctx ww_ctx;
int ret = 0;
if (regulator->always_on)
return 0;
- regulator_lock_dependent(rdev);
+ regulator_lock_dependent(rdev, &ww_ctx);
ret = _regulator_disable(rdev);
- if (rdev->coupling_desc.n_coupled > 1)
- regulator_balance_voltage(rdev, PM_SUSPEND_ON);
- regulator_unlock_dependent(rdev);
-
- if (ret == 0 && rdev->supply)
- regulator_disable(rdev->supply);
+ regulator_unlock_dependent(rdev, &ww_ctx);
return ret;
}
@@ -2464,7 +2570,7 @@ static int _regulator_force_disable(struct regulator_dev *rdev)
{
int ret = 0;
- lockdep_assert_held_once(&rdev->mutex);
+ lockdep_assert_held_once(&rdev->mutex.base);
ret = _notifier_call_chain(rdev, REGULATOR_EVENT_FORCE_DISABLE |
REGULATOR_EVENT_PRE_DISABLE, NULL);
@@ -2497,14 +2603,15 @@ static int _regulator_force_disable(struct regulator_dev *rdev)
int regulator_force_disable(struct regulator *regulator)
{
struct regulator_dev *rdev = regulator->rdev;
+ struct ww_acquire_ctx ww_ctx;
int ret;
- regulator_lock_dependent(rdev);
+ regulator_lock_dependent(rdev, &ww_ctx);
regulator->uA_load = 0;
ret = _regulator_force_disable(regulator->rdev);
if (rdev->coupling_desc.n_coupled > 1)
regulator_balance_voltage(rdev, PM_SUSPEND_ON);
- regulator_unlock_dependent(rdev);
+ regulator_unlock_dependent(rdev, &ww_ctx);
if (rdev->supply)
while (rdev->open_count--)
@@ -2518,9 +2625,10 @@ static void regulator_disable_work(struct work_struct *work)
{
struct regulator_dev *rdev = container_of(work, struct regulator_dev,
disable_work.work);
+ struct ww_acquire_ctx ww_ctx;
int count, i, ret;
- regulator_lock(rdev);
+ regulator_lock_dependent(rdev, &ww_ctx);
BUG_ON(!rdev->deferred_disables);
@@ -2541,7 +2649,10 @@ static void regulator_disable_work(struct work_struct *work)
rdev_err(rdev, "Deferred disable failed: %d\n", ret);
}
- regulator_unlock(rdev);
+ if (rdev->coupling_desc.n_coupled > 1)
+ regulator_balance_voltage(rdev, PM_SUSPEND_ON);
+
+ regulator_unlock_dependent(rdev, &ww_ctx);
if (rdev->supply) {
for (i = 0; i < count; i++) {
@@ -2652,9 +2763,9 @@ int regulator_is_enabled(struct regulator *regulator)
if (regulator->always_on)
return 1;
- regulator_lock_dependent(regulator->rdev);
+ regulator_lock(regulator->rdev);
ret = _regulator_is_enabled(regulator->rdev);
- regulator_unlock_dependent(regulator->rdev);
+ regulator_unlock(regulator->rdev);
return ret;
}
@@ -3268,7 +3379,7 @@ static int regulator_get_optimal_voltage(struct regulator_dev *rdev,
int tmp_min = 0;
int tmp_max = INT_MAX;
- lockdep_assert_held_once(&c_rdevs[i]->mutex);
+ lockdep_assert_held_once(&c_rdevs[i]->mutex.base);
ret = regulator_check_consumers(c_rdevs[i],
&tmp_min,
@@ -3479,14 +3590,15 @@ static int regulator_balance_voltage(struct regulator_dev *rdev,
*/
int regulator_set_voltage(struct regulator *regulator, int min_uV, int max_uV)
{
- int ret = 0;
+ struct ww_acquire_ctx ww_ctx;
+ int ret;
- regulator_lock_dependent(regulator->rdev);
+ regulator_lock_dependent(regulator->rdev, &ww_ctx);
ret = regulator_set_voltage_unlocked(regulator, min_uV, max_uV,
PM_SUSPEND_ON);
- regulator_unlock_dependent(regulator->rdev);
+ regulator_unlock_dependent(regulator->rdev, &ww_ctx);
return ret;
}
@@ -3558,18 +3670,19 @@ static int _regulator_set_suspend_voltage(struct regulator *regulator,
int regulator_set_suspend_voltage(struct regulator *regulator, int min_uV,
int max_uV, suspend_state_t state)
{
- int ret = 0;
+ struct ww_acquire_ctx ww_ctx;
+ int ret;
/* PM_SUSPEND_ON is handled by regulator_set_voltage() */
if (regulator_check_states(state) || state == PM_SUSPEND_ON)
return -EINVAL;
- regulator_lock_dependent(regulator->rdev);
+ regulator_lock_dependent(regulator->rdev, &ww_ctx);
ret = _regulator_set_suspend_voltage(regulator, min_uV,
max_uV, state);
- regulator_unlock_dependent(regulator->rdev);
+ regulator_unlock_dependent(regulator->rdev, &ww_ctx);
return ret;
}
@@ -3759,13 +3872,12 @@ static int _regulator_get_voltage(struct regulator_dev *rdev)
*/
int regulator_get_voltage(struct regulator *regulator)
{
+ struct ww_acquire_ctx ww_ctx;
int ret;
- regulator_lock_dependent(regulator->rdev);
-
+ regulator_lock_dependent(regulator->rdev, &ww_ctx);
ret = _regulator_get_voltage(regulator->rdev);
-
- regulator_unlock_dependent(regulator->rdev);
+ regulator_unlock_dependent(regulator->rdev, &ww_ctx);
return ret;
}
@@ -4301,7 +4413,7 @@ EXPORT_SYMBOL_GPL(regulator_bulk_free);
int regulator_notifier_call_chain(struct regulator_dev *rdev,
unsigned long event, void *data)
{
- lockdep_assert_held_once(&rdev->mutex);
+ lockdep_assert_held_once(&rdev->mutex.base);
_notifier_call_chain(rdev, event, data);
return NOTIFY_DONE;
@@ -4669,7 +4781,7 @@ regulator_register(const struct regulator_desc *regulator_desc,
rdev->dev.of_node = of_node_get(config->of_node);
}
- mutex_init(&rdev->mutex);
+ ww_mutex_init(&rdev->mutex, ®ulator_ww_class);
rdev->reg_data = config->driver_data;
rdev->owner = regulator_desc->owner;
rdev->desc = regulator_desc;
@@ -5026,8 +5138,6 @@ static void regulator_summary_show_subtree(struct seq_file *s,
if (!rdev)
return;
- regulator_lock_nested(rdev, level);
-
opmode = _regulator_get_mode_unlocked(rdev);
seq_printf(s, "%*s%-*s %3d %4d %6d %7s ",
level * 3 + 1, "",
@@ -5084,8 +5194,101 @@ static void regulator_summary_show_subtree(struct seq_file *s,
class_for_each_device(®ulator_class, NULL, &summary_data,
regulator_summary_show_children);
+}
+
+struct summary_lock_data {
+ struct ww_acquire_ctx *ww_ctx;
+ struct regulator_dev **new_contended_rdev;
+ struct regulator_dev **old_contended_rdev;
+};
+
+static int regulator_summary_lock_one(struct device *dev, void *data)
+{
+ struct regulator_dev *rdev = dev_to_rdev(dev);
+ struct summary_lock_data *lock_data = data;
+ int ret = 0;
+
+ if (rdev != *lock_data->old_contended_rdev) {
+ ret = regulator_lock_nested(rdev, lock_data->ww_ctx);
+
+ if (ret == -EDEADLK)
+ *lock_data->new_contended_rdev = rdev;
+ else
+ WARN_ON_ONCE(ret);
+ } else {
+ *lock_data->old_contended_rdev = NULL;
+ }
+
+ return ret;
+}
+
+static int regulator_summary_unlock_one(struct device *dev, void *data)
+{
+ struct regulator_dev *rdev = dev_to_rdev(dev);
+ struct summary_lock_data *lock_data = data;
+
+ if (lock_data) {
+ if (rdev == *lock_data->new_contended_rdev)
+ return -EDEADLK;
+ }
regulator_unlock(rdev);
+
+ return 0;
+}
+
+static int regulator_summary_lock_all(struct ww_acquire_ctx *ww_ctx,
+ struct regulator_dev **new_contended_rdev,
+ struct regulator_dev **old_contended_rdev)
+{
+ struct summary_lock_data lock_data;
+ int ret;
+
+ lock_data.ww_ctx = ww_ctx;
+ lock_data.new_contended_rdev = new_contended_rdev;
+ lock_data.old_contended_rdev = old_contended_rdev;
+
+ ret = class_for_each_device(®ulator_class, NULL, &lock_data,
+ regulator_summary_lock_one);
+ if (ret)
+ class_for_each_device(®ulator_class, NULL, &lock_data,
+ regulator_summary_unlock_one);
+
+ return ret;
+}
+
+static void regulator_summary_lock(struct ww_acquire_ctx *ww_ctx)
+{
+ struct regulator_dev *new_contended_rdev = NULL;
+ struct regulator_dev *old_contended_rdev = NULL;
+ int err;
+
+ ww_acquire_init(ww_ctx, ®ulator_ww_class);
+
+ do {
+ if (new_contended_rdev) {
+ ww_mutex_lock_slow(&new_contended_rdev->mutex, ww_ctx);
+ old_contended_rdev = new_contended_rdev;
+ old_contended_rdev->ref_cnt++;
+ }
+
+ err = regulator_summary_lock_all(ww_ctx,
+ &new_contended_rdev,
+ &old_contended_rdev);
+
+ if (old_contended_rdev)
+ regulator_unlock(old_contended_rdev);
+
+ } while (err == -EDEADLK);
+
+ ww_acquire_done(ww_ctx);
+}
+
+static void regulator_summary_unlock(struct ww_acquire_ctx *ww_ctx)
+{
+ class_for_each_device(®ulator_class, NULL, NULL,
+ regulator_summary_unlock_one);
+ ww_acquire_fini(ww_ctx);
}
static int regulator_summary_show_roots(struct device *dev, void *data)
@@ -5101,12 +5304,18 @@ static int regulator_summary_show_roots(struct device *dev, void *data)
static int regulator_summary_show(struct seq_file *s, void *data)
{
+ struct ww_acquire_ctx ww_ctx;
+
seq_puts(s, " regulator use open bypass opmode voltage current min max\n");
seq_puts(s, "---------------------------------------------------------------------------------------\n");
+ regulator_summary_lock(&ww_ctx);
+
class_for_each_device(®ulator_class, NULL, s,
regulator_summary_show_roots);
+ regulator_summary_unlock(&ww_ctx);
+
return 0;
}
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index a05d37d0efa1..e71f9c314426 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -20,6 +20,7 @@
#include <linux/device.h>
#include <linux/notifier.h>
#include <linux/regulator/consumer.h>
+#include <linux/ww_mutex.h>
struct gpio_desc;
struct regmap;
@@ -462,7 +463,7 @@ struct regulator_dev {
struct coupling_desc coupling_desc;
struct blocking_notifier_head notifier;
- struct mutex mutex; /* consumer lock */
+ struct ww_mutex mutex; /* consumer lock */
struct task_struct *mutex_owner;
int ref_cnt;
struct module *owner;
--
2.19.0
