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task_work: remove legacy TWA_SIGNAL path

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All archs now support TIF_NOTIFY_SIGNAL.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Jens Axboe 2020-10-09 16:01:33 -06:00
parent f50a7052f5
commit 03941ccfda
1 changed files with 1 additions and 29 deletions
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30
kernel/task_work.c
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@ -5,34 +5,6 @@
static struct callback_head work_exited; /* all we need is ->next == NULL */
/*
* TWA_SIGNAL signaling - use TIF_NOTIFY_SIGNAL, if available, as it's faster
* than TIF_SIGPENDING as there's no dependency on ->sighand. The latter is
* shared for threads, and can cause contention on sighand->lock. Even for
* the non-threaded case TIF_NOTIFY_SIGNAL is more efficient, as no locking
* or IRQ disabling is involved for notification (or running) purposes.
*/
static void task_work_notify_signal(struct task_struct *task)
{
#if defined(TIF_NOTIFY_SIGNAL)
set_notify_signal(task);
#else
unsigned long flags;
/*
* Only grab the sighand lock if we don't already have some
* task_work pending. This pairs with the smp_store_mb()
* in get_signal(), see comment there.
*/
if (!(READ_ONCE(task->jobctl) & JOBCTL_TASK_WORK) &&
lock_task_sighand(task, &flags)) {
task->jobctl |= JOBCTL_TASK_WORK;
signal_wake_up(task, 0);
unlock_task_sighand(task, &flags);
}
#endif
}
/**
* task_work_add - ask the @task to execute @work->func()
* @task: the task which should run the callback
@ -76,7 +48,7 @@ int task_work_add(struct task_struct *task, struct callback_head *work,
set_notify_resume(task);
break;
case TWA_SIGNAL:
task_work_notify_signal(task);
set_notify_signal(task);
break;
default:
WARN_ON_ONCE(1);