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io_uring: don't wait when under-submitting 

[ Upstream commit 7c504e6520 ]

There is no reliable way to submit and wait in a single syscall, as
io_submit_sqes() may under-consume sqes (in case of an early error).
Then it will wait for not-yet-submitted requests, deadlocking the user
in most cases.

Don't wait/poll if can't submit all sqes

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Pavel Begunkov 2019-12-18 19:53:45 +03:00 committed by Greg Kroah-Hartman
parent 2d26e06cb1
commit 0023527474
1 changed files with 4 additions and 0 deletions
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4
fs/io_uring.c
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@ -3721,6 +3721,9 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
mutex_lock(&ctx->uring_lock);
submitted = io_ring_submit(ctx, to_submit);
mutex_unlock(&ctx->uring_lock);
if (submitted != to_submit)
goto out;
}
if (flags & IORING_ENTER_GETEVENTS) {
unsigned nr_events = 0;
@ -3734,6 +3737,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
}
}
out:
percpu_ref_put(&ctx->refs);
out_fput:
fdput(f);