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// SPDX-License-Identifier: GPL-2.0-only #include <linux/user-return-notifier.h> #include <linux/percpu.h> #include <linux/sched.h> #include <linux/export.h> static DEFINE_PER_CPU(struct hlist_head, return_notifier_list); /* * Request a notification when the current cpu returns to userspace. Must be * called in atomic context. The notifier will also be called in atomic * context. */ void user_return_notifier_register(struct user_return_notifier *urn) { set_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY); hlist_add_head(&urn->link, this_cpu_ptr(&return_notifier_list)); } EXPORT_SYMBOL_GPL(user_return_notifier_register); /* * Removes a registered user return notifier. Must be called from atomic * context, and from the same cpu registration occurred in. */ void user_return_notifier_unregister(struct user_return_notifier *urn) { hlist_del(&urn->link); if (hlist_empty(this_cpu_ptr(&return_notifier_list))) clear_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY); } EXPORT_SYMBOL_GPL(user_return_notifier_unregister); /* Calls registered user return notifiers */ void fire_user_return_notifiers(void) { struct user_return_notifier *urn; struct hlist_node *tmp2; struct hlist_head *head; head = &get_cpu_var(return_notifier_list); hlist_for_each_entry_safe(urn, tmp2, head, link) urn->on_user_return(urn); put_cpu_var(return_notifier_list); } |