AcoSail/kernel_optimize_test
8
0
Fork 0
forked from luck/tmp_suning_uos_patched
Code Pull Requests Activity

io_uring: remove racy overflow list fast checks

Browse Source 
[ 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>
This commit is contained in:
Pavel Begunkov 2020-12-17 00:24:36 +00:00 committed by Greg Kroah-Hartman
parent 13f9eec229
commit c7b04d27c9
1 changed files with 1 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
fs/io_uring.c
View File

@ -1636,8 +1636,6 @@ 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;
@ -6579,8 +6577,7 @@ 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;
}