deal with task_work callbacks adding more work

It doesn't matter on normal return to userland path (we'll recheck the
NOTIFY_RESUME flag anyway), but in case of exit_task_work() we'll
need that as soon as we get callbacks capable of triggering more
task_work_add().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

1 files changed, 14 insertions, 12 deletions

diff --git a/kernel/task_work.c b/kernel/task_work.c
index fb396089f66a..91d4e1742a0c 100644
--- a/kernel/task_work.c
+++ b/kernel/task_work.c
@@ -60,19 +60,21 @@ void task_work_run(void)
         struct task_struct *task = current;
         struct callback_head *p, *q;
 
-        raw_spin_lock_irq(&task->pi_lock);
-        p = task->task_works;
-        task->task_works = NULL;
-        raw_spin_unlock_irq(&task->pi_lock);
+        while (1) {
+                raw_spin_lock_irq(&task->pi_lock);
+                p = task->task_works;
+                task->task_works = NULL;
+                raw_spin_unlock_irq(&task->pi_lock);
 
-        if (unlikely(!p))
-                return;
+                if (unlikely(!p))
+                        return;
 
-        q = p->next; /* head */
-        p->next = NULL; /* cut it */
-        while (q) {
-                p = q->next;
-                q->func(q);
-                q = p;
+                q = p->next; /* head */
+                p->next = NULL; /* cut it */
+                while (q) {
+                        p = q->next;
+                        q->func(q);
+                        q = p;
+                }
         }
 }