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io_uring: remove racy overflow list fast checks

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list_empty_careful() is not racy only if some conditions are met, i.e.
no re-adds after del_init. io_cqring_overflow_flush() does list_move(),
so it's actually racy.

Remove those checks, we have ->cq_check_overflow for the fast path.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Pavel Begunkov 2020-12-17 00:24:36 +00:00 committed by Jens Axboe
parent cda286f071
commit 9cd2be519d
1 changed files with 1 additions and 4 deletions
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5
fs/io_uring.c
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@ -1724,8 +1724,6 @@ static bool io_cqring_overflow_flush(struct io_ring_ctx *ctx, bool force,
LIST_HEAD(list);
if (!force) {
if (list_empty_careful(&ctx->cq_overflow_list))
return true;
if ((ctx->cached_cq_tail - READ_ONCE(rings->cq.head) ==
rings->cq_ring_entries))
return false;
@ -6822,8 +6820,7 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr)
/* if we have a backlog and couldn't flush it all, return BUSY */
if (test_bit(0, &ctx->sq_check_overflow)) {
if (!list_empty(&ctx->cq_overflow_list) &&
!io_cqring_overflow_flush(ctx, false, NULL, NULL))
if (!io_cqring_overflow_flush(ctx, false, NULL, NULL))
return -EBUSY;
}