1 files changed, 41 insertions, 0 deletions

diff --git a/kernel/livepatch/transition.c b/kernel/livepatch/transition.c
index 56add6327736..edcfcb8ebb2d 100644
--- a/kernel/livepatch/transition.c
+++ b/kernel/livepatch/transition.c
@@ -608,3 +608,44 @@ void klp_copy_process(struct task_struct *child)
 
         /* TIF_PATCH_PENDING gets copied in setup_thread_stack() */
 }
+
+/*
+ * Sends a fake signal to all non-kthread tasks with TIF_PATCH_PENDING set.
+ * Kthreads with TIF_PATCH_PENDING set are woken up. Only admin can request this
+ * action currently.
+ */
+void klp_send_signals(void)
+{
+        struct task_struct *g, *task;
+
+        pr_notice("signaling remaining tasks\n");
+
+        read_lock(&tasklist_lock);
+        for_each_process_thread(g, task) {
+                if (!klp_patch_pending(task))
+                        continue;
+
+                /*
+                 * There is a small race here. We could see TIF_PATCH_PENDING
+                 * set and decide to wake up a kthread or send a fake signal.
+                 * Meanwhile the task could migrate itself and the action
+                 * would be meaningless. It is not serious though.
+                 */
+                if (task->flags & PF_KTHREAD) {
+                        /*
+                         * Wake up a kthread which sleeps interruptedly and
+                         * still has not been migrated.
+                         */
+                        wake_up_state(task, TASK_INTERRUPTIBLE);
+                } else {
+                        /*
+                         * Send fake signal to all non-kthread tasks which are
+                         * still not migrated.
+                         */
+                        spin_lock_irq(&task->sighand->siglock);
+                        signal_wake_up(task, 0);
+                        spin_unlock_irq(&task->sighand->siglock);
+                }
+        }
+        read_unlock(&tasklist_lock);
+}