diff --git a/drivers/reset/core.c b/drivers/reset/core.c index 2102093624aa..e6c12fbebca9 100644 --- a/drivers/reset/core.c +++ b/drivers/reset/core.c @@ -23,6 +23,7 @@ #include #include #include +#include static DEFINE_MUTEX(reset_list_mutex); static LIST_HEAD(reset_controller_list); @@ -36,6 +37,7 @@ static DEFINE_IDA(reset_gpio_ida); * struct reset_control - a reset control * @rcdev: a pointer to the reset controller device * this reset control belongs to + * @srcu: protects the rcdev pointer from removal during consumer access * @list: list entry for the rcdev's reset controller list * @id: ID of the reset controller in the reset * controller device @@ -49,7 +51,8 @@ static DEFINE_IDA(reset_gpio_ida); * will be either 0 or 1. */ struct reset_control { - struct reset_controller_dev *rcdev; + struct reset_controller_dev __rcu *rcdev; + struct srcu_struct srcu; struct list_head list; unsigned int id; struct kref refcnt; @@ -137,15 +140,35 @@ int reset_controller_register(struct reset_controller_dev *rcdev) } EXPORT_SYMBOL_GPL(reset_controller_register); +static void reset_controller_remove(struct reset_controller_dev *rcdev, + struct reset_control *rstc) +{ + list_del(&rstc->list); + module_put(rcdev->owner); + put_device(rcdev->dev); +} + /** * reset_controller_unregister - unregister a reset controller device * @rcdev: a pointer to the reset controller device */ void reset_controller_unregister(struct reset_controller_dev *rcdev) { + struct reset_control *rstc, *pos; + 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); + } } EXPORT_SYMBOL_GPL(reset_controller_unregister); @@ -322,6 +345,7 @@ static inline bool reset_control_is_array(struct reset_control *rstc) */ int reset_control_reset(struct reset_control *rstc) { + struct reset_controller_dev *rcdev; int ret; if (!rstc) @@ -333,7 +357,13 @@ int reset_control_reset(struct reset_control *rstc) if (reset_control_is_array(rstc)) return reset_control_array_reset(rstc_to_array(rstc)); - if (!rstc->rcdev->ops->reset) + guard(srcu)(&rstc->srcu); + + rcdev = srcu_dereference(rstc->rcdev, &rstc->srcu); + if (!rcdev) + return -ENODEV; + + if (!rcdev->ops->reset) return -ENOTSUPP; if (rstc->shared) { @@ -347,7 +377,7 @@ int reset_control_reset(struct reset_control *rstc) return -EPERM; } - ret = rstc->rcdev->ops->reset(rstc->rcdev, rstc->id); + ret = rcdev->ops->reset(rcdev, rstc->id); if (rstc->shared && ret) atomic_dec(&rstc->triggered_count); @@ -437,6 +467,8 @@ EXPORT_SYMBOL_GPL(reset_control_rearm); */ int reset_control_assert(struct reset_control *rstc) { + struct reset_controller_dev *rcdev; + if (!rstc) return 0; @@ -446,6 +478,12 @@ int reset_control_assert(struct reset_control *rstc) if (reset_control_is_array(rstc)) return reset_control_array_assert(rstc_to_array(rstc)); + guard(srcu)(&rstc->srcu); + + rcdev = srcu_dereference(rstc->rcdev, &rstc->srcu); + if (!rcdev) + return -ENODEV; + if (rstc->shared) { if (WARN_ON(atomic_read(&rstc->triggered_count) != 0)) return -EINVAL; @@ -460,7 +498,7 @@ int reset_control_assert(struct reset_control *rstc) * Shared reset controls allow the reset line to be in any state * after this call, so doing nothing is a valid option. */ - if (!rstc->rcdev->ops->assert) + if (!rcdev->ops->assert) return 0; } else { /* @@ -468,17 +506,17 @@ int reset_control_assert(struct reset_control *rstc) * is no way to guarantee that the reset line is asserted after * this call. */ - if (!rstc->rcdev->ops->assert) + if (!rcdev->ops->assert) return -ENOTSUPP; if (!rstc->acquired) { WARN(1, "reset %s (ID: %u) is not acquired\n", - rcdev_name(rstc->rcdev), rstc->id); + rcdev_name(rcdev), rstc->id); return -EPERM; } } - return rstc->rcdev->ops->assert(rstc->rcdev, rstc->id); + return rcdev->ops->assert(rcdev, rstc->id); } EXPORT_SYMBOL_GPL(reset_control_assert); @@ -525,6 +563,8 @@ EXPORT_SYMBOL_GPL(reset_control_bulk_assert); */ int reset_control_deassert(struct reset_control *rstc) { + struct reset_controller_dev *rcdev; + if (!rstc) return 0; @@ -534,6 +574,12 @@ int reset_control_deassert(struct reset_control *rstc) if (reset_control_is_array(rstc)) return reset_control_array_deassert(rstc_to_array(rstc)); + guard(srcu)(&rstc->srcu); + + rcdev = srcu_dereference(rstc->rcdev, &rstc->srcu); + if (!rcdev) + return -ENODEV; + if (rstc->shared) { if (WARN_ON(atomic_read(&rstc->triggered_count) != 0)) return -EINVAL; @@ -543,7 +589,7 @@ int reset_control_deassert(struct reset_control *rstc) } else { if (!rstc->acquired) { WARN(1, "reset %s (ID: %u) is not acquired\n", - rcdev_name(rstc->rcdev), rstc->id); + rcdev_name(rcdev), rstc->id); return -EPERM; } } @@ -555,10 +601,10 @@ int reset_control_deassert(struct reset_control *rstc) * case, the reset controller driver should implement .deassert() and * return -ENOTSUPP. */ - if (!rstc->rcdev->ops->deassert) + if (!rcdev->ops->deassert) return 0; - return rstc->rcdev->ops->deassert(rstc->rcdev, rstc->id); + return rcdev->ops->deassert(rcdev, rstc->id); } EXPORT_SYMBOL_GPL(reset_control_deassert); @@ -600,14 +646,22 @@ EXPORT_SYMBOL_GPL(reset_control_bulk_deassert); */ int reset_control_status(struct reset_control *rstc) { + struct reset_controller_dev *rcdev; + if (!rstc) return 0; if (WARN_ON(IS_ERR(rstc)) || reset_control_is_array(rstc)) return -EINVAL; - if (rstc->rcdev->ops->status) - return rstc->rcdev->ops->status(rstc->rcdev, rstc->id); + guard(srcu)(&rstc->srcu); + + rcdev = srcu_dereference(rstc->rcdev, &rstc->srcu); + if (!rcdev) + return -ENODEV; + + if (rcdev->ops->status) + return rcdev->ops->status(rcdev, rstc->id); return -ENOTSUPP; } @@ -635,6 +689,7 @@ EXPORT_SYMBOL_GPL(reset_control_status); */ int reset_control_acquire(struct reset_control *rstc) { + struct reset_controller_dev *rcdev; struct reset_control *rc; if (!rstc) @@ -651,7 +706,13 @@ int reset_control_acquire(struct reset_control *rstc) if (rstc->acquired) return 0; - list_for_each_entry(rc, &rstc->rcdev->reset_control_head, list) { + guard(srcu)(&rstc->srcu); + + rcdev = srcu_dereference(rstc->rcdev, &rstc->srcu); + 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; @@ -743,6 +804,7 @@ __reset_control_get_internal(struct reset_controller_dev *rcdev, bool shared = flags & RESET_CONTROL_FLAGS_BIT_SHARED; bool acquired = flags & RESET_CONTROL_FLAGS_BIT_ACQUIRED; struct reset_control *rstc; + int ret; lockdep_assert_held(&reset_list_mutex); @@ -773,12 +835,19 @@ __reset_control_get_internal(struct reset_controller_dev *rcdev, if (!rstc) return ERR_PTR(-ENOMEM); + ret = init_srcu_struct(&rstc->srcu); + if (ret) { + kfree(rstc); + return ERR_PTR(ret); + } + if (!try_module_get(rcdev->owner)) { + cleanup_srcu_struct(&rstc->srcu); kfree(rstc); return ERR_PTR(-ENODEV); } - rstc->rcdev = rcdev; + rcu_assign_pointer(rstc->rcdev, rcdev); list_add(&rstc->list, &rcdev->reset_control_head); rstc->id = index; kref_init(&rstc->refcnt); @@ -793,13 +862,18 @@ static void __reset_control_release(struct kref *kref) { struct reset_control *rstc = container_of(kref, struct reset_control, refcnt); + struct reset_controller_dev *rcdev; lockdep_assert_held(&reset_list_mutex); - module_put(rstc->rcdev->owner); + scoped_guard(srcu, &rstc->srcu) { + rcdev = rcu_replace_pointer(rstc->rcdev, NULL, true); + if (rcdev) + reset_controller_remove(rcdev, rstc); + } - list_del(&rstc->list); - put_device(rstc->rcdev->dev); + synchronize_srcu(&rstc->srcu); + cleanup_srcu_struct(&rstc->srcu); kfree(rstc); }