Blame view
kernel/task_work.c
3.36 KB
e73f8959a task_work_add: ge... |
1 2 3 |
#include <linux/spinlock.h> #include <linux/task_work.h> #include <linux/tracehook.h> |
9da33de62 task_work: task_w... |
4 |
static struct callback_head work_exited; /* all we need is ->next == NULL */ |
892f6668f task_work: docume... |
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 |
/** * task_work_add - ask the @task to execute @work->func() * @task: the task which should run the callback * @work: the callback to run * @notify: send the notification if true * * Queue @work for task_work_run() below and notify the @task if @notify. * Fails if the @task is exiting/exited and thus it can't process this @work. * Otherwise @work->func() will be called when the @task returns from kernel * mode or exits. * * This is like the signal handler which runs in kernel mode, but it doesn't * try to wake up the @task. * * RETURNS: * 0 if succeeds or -ESRCH. */ |
e73f8959a task_work_add: ge... |
22 |
int |
ac3d0da8f task_work: Make t... |
23 |
task_work_add(struct task_struct *task, struct callback_head *work, bool notify) |
e73f8959a task_work_add: ge... |
24 |
{ |
ac3d0da8f task_work: Make t... |
25 |
struct callback_head *head; |
9da33de62 task_work: task_w... |
26 |
|
ac3d0da8f task_work: Make t... |
27 28 |
do { head = ACCESS_ONCE(task->task_works); |
9da33de62 task_work: task_w... |
29 30 |
if (unlikely(head == &work_exited)) return -ESRCH; |
ac3d0da8f task_work: Make t... |
31 32 |
work->next = head; } while (cmpxchg(&task->task_works, head, work) != head); |
e73f8959a task_work_add: ge... |
33 |
|
ed3e694d7 move exit_task_wo... |
34 |
if (notify) |
e73f8959a task_work_add: ge... |
35 |
set_notify_resume(task); |
ed3e694d7 move exit_task_wo... |
36 |
return 0; |
e73f8959a task_work_add: ge... |
37 |
} |
892f6668f task_work: docume... |
38 39 40 41 42 43 44 45 46 47 48 |
/** * task_work_cancel - cancel a pending work added by task_work_add() * @task: the task which should execute the work * @func: identifies the work to remove * * Find the last queued pending work with ->func == @func and remove * it from queue. * * RETURNS: * The found work or NULL if not found. */ |
67d121455 merge task_work a... |
49 |
struct callback_head * |
e73f8959a task_work_add: ge... |
50 51 |
task_work_cancel(struct task_struct *task, task_work_func_t func) { |
ac3d0da8f task_work: Make t... |
52 |
struct callback_head **pprev = &task->task_works; |
205e550a0 task_work: minor ... |
53 |
struct callback_head *work; |
e73f8959a task_work_add: ge... |
54 |
unsigned long flags; |
ac3d0da8f task_work: Make t... |
55 56 57 58 |
/* * If cmpxchg() fails we continue without updating pprev. * Either we raced with task_work_add() which added the * new entry before this work, we will find it again. Or |
9da33de62 task_work: task_w... |
59 |
* we raced with task_work_run(), *pprev == NULL/exited. |
ac3d0da8f task_work: Make t... |
60 |
*/ |
e73f8959a task_work_add: ge... |
61 |
raw_spin_lock_irqsave(&task->pi_lock, flags); |
ac3d0da8f task_work: Make t... |
62 |
while ((work = ACCESS_ONCE(*pprev))) { |
205e550a0 task_work: minor ... |
63 |
smp_read_barrier_depends(); |
ac3d0da8f task_work: Make t... |
64 65 66 67 |
if (work->func != func) pprev = &work->next; else if (cmpxchg(pprev, work, work->next) == work) break; |
e73f8959a task_work_add: ge... |
68 |
} |
e73f8959a task_work_add: ge... |
69 |
raw_spin_unlock_irqrestore(&task->pi_lock, flags); |
ac3d0da8f task_work: Make t... |
70 71 |
return work; |
e73f8959a task_work_add: ge... |
72 |
} |
892f6668f task_work: docume... |
73 74 75 76 77 78 79 80 |
/** * task_work_run - execute the works added by task_work_add() * * Flush the pending works. Should be used by the core kernel code. * Called before the task returns to the user-mode or stops, or when * it exits. In the latter case task_work_add() can no longer add the * new work after task_work_run() returns. */ |
e73f8959a task_work_add: ge... |
81 82 83 |
void task_work_run(void) { struct task_struct *task = current; |
ac3d0da8f task_work: Make t... |
84 |
struct callback_head *work, *head, *next; |
e73f8959a task_work_add: ge... |
85 |
|
ac3d0da8f task_work: Make t... |
86 |
for (;;) { |
9da33de62 task_work: task_w... |
87 88 89 90 91 92 93 94 95 |
/* * work->func() can do task_work_add(), do not set * work_exited unless the list is empty. */ do { work = ACCESS_ONCE(task->task_works); head = !work && (task->flags & PF_EXITING) ? &work_exited : NULL; } while (cmpxchg(&task->task_works, work, head) != work); |
ac3d0da8f task_work: Make t... |
96 97 98 99 100 101 102 103 104 |
if (!work) break; /* * Synchronize with task_work_cancel(). It can't remove * the first entry == work, cmpxchg(task_works) should * fail, but it can play with *work and other entries. */ raw_spin_unlock_wait(&task->pi_lock); smp_mb(); |
e73f8959a task_work_add: ge... |
105 |
|
ac3d0da8f task_work: Make t... |
106 107 108 109 110 111 112 113 |
/* Reverse the list to run the works in fifo order */ head = NULL; do { next = work->next; work->next = head; head = work; work = next; } while (work); |
e73f8959a task_work_add: ge... |
114 |
|
ac3d0da8f task_work: Make t... |
115 116 117 118 119 |
work = head; do { next = work->next; work->func(work); work = next; |
f341861fb task_work: add a ... |
120 |
cond_resched(); |
ac3d0da8f task_work: Make t... |
121 |
} while (work); |
e73f8959a task_work_add: ge... |
122 123 |
} } |