Merge tag 'please-pull-naveen' of git://git.kernel.org/pub/scm/linux/kernel/git/ras...
[linux-3.10.git] / kernel / task_work.c
1 #include <linux/spinlock.h>
2 #include <linux/task_work.h>
3 #include <linux/tracehook.h>
4
5 int
6 task_work_add(struct task_struct *task, struct callback_head *twork, bool notify)
7 {
8         struct callback_head *last, *first;
9         unsigned long flags;
10
11         /*
12          * Not inserting the new work if the task has already passed
13          * exit_task_work() is the responisbility of callers.
14          */
15         raw_spin_lock_irqsave(&task->pi_lock, flags);
16         last = task->task_works;
17         first = last ? last->next : twork;
18         twork->next = first;
19         if (last)
20                 last->next = twork;
21         task->task_works = twork;
22         raw_spin_unlock_irqrestore(&task->pi_lock, flags);
23
24         /* test_and_set_bit() implies mb(), see tracehook_notify_resume(). */
25         if (notify)
26                 set_notify_resume(task);
27         return 0;
28 }
29
30 struct callback_head *
31 task_work_cancel(struct task_struct *task, task_work_func_t func)
32 {
33         unsigned long flags;
34         struct callback_head *last, *res = NULL;
35
36         raw_spin_lock_irqsave(&task->pi_lock, flags);
37         last = task->task_works;
38         if (last) {
39                 struct callback_head *q = last, *p = q->next;
40                 while (1) {
41                         if (p->func == func) {
42                                 q->next = p->next;
43                                 if (p == last)
44                                         task->task_works = q == p ? NULL : q;
45                                 res = p;
46                                 break;
47                         }
48                         if (p == last)
49                                 break;
50                         q = p;
51                         p = q->next;
52                 }
53         }
54         raw_spin_unlock_irqrestore(&task->pi_lock, flags);
55         return res;
56 }
57
58 void task_work_run(void)
59 {
60         struct task_struct *task = current;
61         struct callback_head *p, *q;
62
63         while (1) {
64                 raw_spin_lock_irq(&task->pi_lock);
65                 p = task->task_works;
66                 task->task_works = NULL;
67                 raw_spin_unlock_irq(&task->pi_lock);
68
69                 if (unlikely(!p))
70                         return;
71
72                 q = p->next; /* head */
73                 p->next = NULL; /* cut it */
74                 while (q) {
75                         p = q->next;
76                         q->func(q);
77                         q = p;
78                         cond_resched();
79                 }
80         }
81 }