From: Pavel Begunkov asml.silence@gmail.com
[ Upstream commit 9cd2be519d05ee78876d55e8e902b7125f78b74f ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- fs/io_uring.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/fs/io_uring.c b/fs/io_uring.c index 86dac2b2e2763..4b3dbe588d111 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1632,8 +1632,6 @@ 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; @@ -6548,8 +6546,7 @@ 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; }