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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 18:49:45 +0000
commit2c3c1048746a4622d8c89a29670120dc8fab93c4 (patch)
tree848558de17fb3008cdf4d861b01ac7781903ce39 /kernel/user-return-notifier.c
parentInitial commit. (diff)
downloadlinux-2c3c1048746a4622d8c89a29670120dc8fab93c4.tar.xz
linux-2c3c1048746a4622d8c89a29670120dc8fab93c4.zip
Adding upstream version 6.1.76.upstream/6.1.76
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'kernel/user-return-notifier.c')
-rw-r--r--kernel/user-return-notifier.c45
1 files changed, 45 insertions, 0 deletions
diff --git a/kernel/user-return-notifier.c b/kernel/user-return-notifier.c
new file mode 100644
index 000000000..870ecd7c6
--- /dev/null
+++ b/kernel/user-return-notifier.c
@@ -0,0 +1,45 @@
+// 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);
+}