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io_uring: don't resched with empty task_list

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Entering tctx_task_work() with empty task_list is a strange scenario,
that can happen only on rare occasion during task exit, so let's not
check for task_list emptiness in advance and do it do-while style. The
code still correct for the empty case, just would do extra work about
which we don't care.

Do extra step and do the check before cond_resched(), so we don't
resched if have nothing to execute.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/c4173e288e69793d03c7d7ce826f9d28afba718a.1623949695.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-06-17 18:14:09 +01:00 committed by Jens Axboe
parent c6538be9e4
commit 16f7207038
1 changed files with 3 additions and 1 deletions
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4
fs/io_uring.c
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@ -1896,7 +1896,7 @@ static void tctx_task_work(struct callback_head *cb)
clear_bit(0, &tctx->task_state);
while (!wq_list_empty(&tctx->task_list)) {
while (1) {
struct io_wq_work_node *node;
spin_lock_irq(&tctx->task_lock);
@ -1917,6 +1917,8 @@ static void tctx_task_work(struct callback_head *cb)
req->task_work.func(&req->task_work);
node = next;
}
if (wq_list_empty(&tctx->task_list))
break;
cond_resched();
}