Messages in this thread Patch in this message |  | | Date | Sun, 09 Aug 2020 23:16:53 +0200 | From | Michał Mirosław <> | Subject | [PATCH] regulator: simplify locking |
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Simplify regulator locking by removing locking around locking. rdev->ref is now accessed only when the lock is taken. The code still smells fishy, but now its obvious why.
Fixes: f8702f9e4aa7 ("regulator: core: Use ww_mutex for regulators locking") Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl> --- drivers/regulator/core.c | 37 ++++++-------------------------- include/linux/regulator/driver.h | 1 - 2 files changed, 6 insertions(+), 32 deletions(-)
diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c index 9e18997777d3..b0662927487c 100644 --- a/drivers/regulator/core.c +++ b/drivers/regulator/core.c @@ -45,7 +45,6 @@ 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); @@ -150,32 +149,13 @@ static bool regulator_ops_is_valid(struct regulator_dev *rdev, int ops) static inline int regulator_lock_nested(struct regulator_dev *rdev, struct ww_acquire_ctx *ww_ctx) { - bool lock = false; int ret = 0; - mutex_lock(®ulator_nesting_mutex); + if (ww_ctx || !mutex_trylock_recursive(&rdev->mutex.base)) + ret = ww_mutex_lock(&rdev->mutex, ww_ctx); - if (ww_ctx || !ww_mutex_trylock(&rdev->mutex)) { - if (rdev->mutex_owner == current) - rdev->ref_cnt++; - else - lock = true; - - if (lock) { - mutex_unlock(®ulator_nesting_mutex); - ret = ww_mutex_lock(&rdev->mutex, ww_ctx); - mutex_lock(®ulator_nesting_mutex); - } - } else { - lock = true; - } - - if (lock && ret != -EDEADLK) { + if (ret != -EDEADLK) rdev->ref_cnt++; - rdev->mutex_owner = current; - } - - mutex_unlock(®ulator_nesting_mutex); return ret; } @@ -205,16 +185,11 @@ EXPORT_SYMBOL_GPL(regulator_lock); */ void regulator_unlock(struct regulator_dev *rdev) { - mutex_lock(®ulator_nesting_mutex); + if (WARN_ON_ONCE(rdev->ref_cnt <= 0)) + return; - if (--rdev->ref_cnt == 0) { - rdev->mutex_owner = NULL; + if (--rdev->ref_cnt == 0) ww_mutex_unlock(&rdev->mutex); - } - - WARN_ON_ONCE(rdev->ref_cnt < 0); - - mutex_unlock(®ulator_nesting_mutex); } EXPORT_SYMBOL_GPL(regulator_unlock); diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h index 8539f34ae42b..2fe5b1bcbe2f 100644 --- a/include/linux/regulator/driver.h +++ b/include/linux/regulator/driver.h @@ -448,7 +448,6 @@ struct regulator_dev { struct blocking_notifier_head notifier; struct ww_mutex mutex; /* consumer lock */ - struct task_struct *mutex_owner; int ref_cnt; struct module *owner; struct device dev; -- 2.20.1
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