[PATCH 5.10 003/103] io_uring: limit {io|sq}poll submit locking scope

Greg Kroah-Hartman
2021-01-15T12:48:16Z

From: Pavel Begunkov <asml.silence@gmail.com>

commit 89448c47b8452b67c146dc6cad6f737e004c5caf upstream

We don't need to take uring_lock for SQPOLL|IOPOLL to do
io_cqring_overflow_flush() when cq_overflow_list is empty, remove it
from the hot 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 | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 3974b4f124b6a..5ba312ab99786 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9024,10 +9024,13 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
*/
ret = 0;
if (ctx->flags & IORING_SETUP_SQPOLL) {
- io_ring_submit_lock(ctx, (ctx->flags & IORING_SETUP_IOPOLL));
- if (!list_empty_careful(&ctx->cq_overflow_list))
+ if (!list_empty_careful(&ctx->cq_overflow_list)) {
+ bool needs_lock = ctx->flags & IORING_SETUP_IOPOLL;
+
+ io_ring_submit_lock(ctx, needs_lock);
io_cqring_overflow_flush(ctx, false, NULL, NULL);
- io_ring_submit_unlock(ctx, (ctx->flags & IORING_SETUP_IOPOLL));
+ io_ring_submit_unlock(ctx, needs_lock);
+ }
if (flags & IORING_ENTER_SQ_WAKEUP)
wake_up(&ctx->sq_data->wait);
if (flags & IORING_ENTER_SQ_WAIT)
--
2.27.0