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io_uring: refactor io_cqring_wait

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It's easy to make a mistake in io_cqring_wait() because for all
break/continue clauses we need to watch for prepare/finish_wait to be
used correctly. Extract all those into a new helper
io_cqring_wait_schedule(), and transforming the loop into simple series
of func calls: prepare(); check_and_schedule(); finish();

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2021-02-04 13:51:58 +00:00 committed by Jens Axboe
parent c1d5a22468
commit eeb60b9ab4
1 changed files with 22 additions and 21 deletions
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43
fs/io_uring.c
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@ -7195,6 +7195,25 @@ static int io_run_task_work_sig(void)
return -EINTR;
}
/* when returns >0, the caller should retry */
static inline int io_cqring_wait_schedule(struct io_ring_ctx *ctx,
struct io_wait_queue *iowq,
signed long *timeout)
{
int ret;
/* make sure we run task_work before checking for signals */
ret = io_run_task_work_sig();
if (ret || io_should_wake(iowq))
return ret;
/* let the caller flush overflows, retry */
if (test_bit(0, &ctx->cq_check_overflow))
return 1;
*timeout = schedule_timeout(*timeout);
return !*timeout ? -ETIME : 1;
}
/*
* Wait until events become available, if we don't already have some. The
* application must reap them itself, as they reside on the shared cq ring.
@ -7251,27 +7270,9 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
io_cqring_overflow_flush(ctx, false, NULL, NULL);
prepare_to_wait_exclusive(&ctx->wait, &iowq.wq,
TASK_INTERRUPTIBLE);
/* make sure we run task_work before checking for signals */
ret = io_run_task_work_sig();
if (ret > 0) {
finish_wait(&ctx->wait, &iowq.wq);
continue;
}
else if (ret < 0)
break;
if (io_should_wake(&iowq))
break;
if (test_bit(0, &ctx->cq_check_overflow)) {
finish_wait(&ctx->wait, &iowq.wq);
continue;
}
timeout = schedule_timeout(timeout);
if (timeout == 0) {
ret = -ETIME;
break;
}
} while (1);
finish_wait(&ctx->wait, &iowq.wq);
ret = io_cqring_wait_schedule(ctx, &iowq, &timeout);
finish_wait(&ctx->wait, &iowq.wq);
} while (ret > 0);
restore_saved_sigmask_unless(ret == -EINTR);