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Locking can be made a lot more fine-grained if we use a separate mutex for serializing operations on the list AND accessing the reset controller device. Signed-off-by: Bartosz Golaszewski --- drivers/reset/core.c | 44 ++++++++++++++++++++++++---------------- include/linux/reset-controller.h | 3 +++ 2 files changed, 30 insertions(+), 17 deletions(-) diff --git a/drivers/reset/core.c b/drivers/reset/core.c index 96199e7b0dd7c89c5a11e2e2c3e5eb7fd5d49355..d4813c712abf3df7993b0c2be1fe292b89241d11 100644 --- a/drivers/reset/core.c +++ b/drivers/reset/core.c @@ -131,6 +131,7 @@ int reset_controller_register(struct reset_controller_dev *rcdev) } INIT_LIST_HEAD(&rcdev->reset_control_head); + mutex_init(&rcdev->lock); guard(mutex)(&reset_list_mutex); @@ -143,6 +144,8 @@ EXPORT_SYMBOL_GPL(reset_controller_register); static void reset_controller_remove(struct reset_controller_dev *rcdev, struct reset_control *rstc) { + lockdep_assert_held(&rcdev->lock); + list_del(&rstc->list); module_put(rcdev->owner); put_device(rcdev->dev); @@ -156,19 +159,22 @@ void reset_controller_unregister(struct reset_controller_dev *rcdev) { struct reset_control *rstc, *pos; - guard(mutex)(&reset_list_mutex); - - list_del(&rcdev->list); + scoped_guard(mutex, &reset_list_mutex) + list_del(&rcdev->list); - /* - * Numb but don't free the remaining reset control handles that are - * still held by consumers. - */ - list_for_each_entry_safe(rstc, pos, &rcdev->reset_control_head, list) { - rcu_assign_pointer(rstc->rcdev, NULL); - synchronize_srcu(&rstc->srcu); - reset_controller_remove(rcdev, rstc); + scoped_guard(mutex, &rcdev->lock) { + /* + * Numb but don't free the remaining reset control handles that are + * still held by consumers. + */ + list_for_each_entry_safe(rstc, pos, &rcdev->reset_control_head, list) { + rcu_assign_pointer(rstc->rcdev, NULL); + synchronize_srcu(&rstc->srcu); + reset_controller_remove(rcdev, rstc); + } } + + mutex_destroy(&rcdev->lock); } EXPORT_SYMBOL_GPL(reset_controller_unregister); @@ -712,10 +718,12 @@ int reset_control_acquire(struct reset_control *rstc) if (!rcdev) return -ENODEV; - list_for_each_entry(rc, &rcdev->reset_control_head, list) { - if (rstc != rc && rstc->id == rc->id) { - if (rc->acquired) - return -EBUSY; + scoped_guard(mutex, &rcdev->lock) { + list_for_each_entry(rc, &rcdev->reset_control_head, list) { + if (rstc != rc && rstc->id == rc->id) { + if (rc->acquired) + return -EBUSY; + } } } @@ -806,7 +814,7 @@ __reset_control_get_internal(struct reset_controller_dev *rcdev, struct reset_control *rstc; int ret; - lockdep_assert_held(&reset_list_mutex); + lockdep_assert_held(&rcdev->lock); /* Expect callers to filter out OPTIONAL and DEASSERTED bits */ if (WARN_ON(flags & ~(RESET_CONTROL_FLAGS_BIT_SHARED | @@ -868,8 +876,10 @@ static void __reset_control_release(struct kref *kref) scoped_guard(srcu, &rstc->srcu) { rcdev = rcu_replace_pointer(rstc->rcdev, NULL, true); - if (rcdev) + if (rcdev) { + guard(mutex)(&rcdev->lock); reset_controller_remove(rcdev, rstc); + } } synchronize_srcu(&rstc->srcu); diff --git a/include/linux/reset-controller.h b/include/linux/reset-controller.h index aa95b460fdf86f10002a465e285cd0119da6eeaf..185d2a9bd7cd381ddc51c0f1643c4e3cb196015e 100644 --- a/include/linux/reset-controller.h +++ b/include/linux/reset-controller.h @@ -3,6 +3,7 @@ #define _LINUX_RESET_CONTROLLER_H_ #include +#include struct reset_controller_dev; @@ -40,6 +41,7 @@ struct of_phandle_args; * device tree to id as given to the reset control ops, defaults * to :c:func:`of_reset_simple_xlate`. * @nr_resets: number of reset controls in this reset controller device + * @lock: protects the reset control list from concurrent access */ struct reset_controller_dev { const struct reset_control_ops *ops; @@ -52,6 +54,7 @@ struct reset_controller_dev { int (*of_xlate)(struct reset_controller_dev *rcdev, const struct of_phandle_args *reset_spec); unsigned int nr_resets; + struct mutex lock; }; #if IS_ENABLED(CONFIG_RESET_CONTROLLER) -- 2.47.3