47 lines
1.4 KiB
C
47 lines
1.4 KiB
C
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#include <linux/user-return-notifier.h>
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#include <linux/percpu.h>
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#include <linux/sched.h>
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#include <linux/module.h>
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static DEFINE_PER_CPU(struct hlist_head, return_notifier_list);
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#define URN_LIST_HEAD per_cpu(return_notifier_list, raw_smp_processor_id())
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/*
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* Request a notification when the current cpu returns to userspace. Must be
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* called in atomic context. The notifier will also be called in atomic
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* context.
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*/
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void user_return_notifier_register(struct user_return_notifier *urn)
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{
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set_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY);
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hlist_add_head(&urn->link, &URN_LIST_HEAD);
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}
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EXPORT_SYMBOL_GPL(user_return_notifier_register);
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/*
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* Removes a registered user return notifier. Must be called from atomic
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* context, and from the same cpu registration occured in.
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*/
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void user_return_notifier_unregister(struct user_return_notifier *urn)
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{
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hlist_del(&urn->link);
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if (hlist_empty(&URN_LIST_HEAD))
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clear_tsk_thread_flag(current, TIF_USER_RETURN_NOTIFY);
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}
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EXPORT_SYMBOL_GPL(user_return_notifier_unregister);
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/* Calls registered user return notifiers */
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void fire_user_return_notifiers(void)
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{
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struct user_return_notifier *urn;
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struct hlist_node *tmp1, *tmp2;
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struct hlist_head *head;
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head = &get_cpu_var(return_notifier_list);
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hlist_for_each_entry_safe(urn, tmp1, tmp2, head, link)
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urn->on_user_return(urn);
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put_cpu_var(return_notifier_list);
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}
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