io_uring: limit {io|sq}poll submit locking scope

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>

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5c9aa8b..8cf6f22 100644 (file)
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -9154,10 +9154,13 @@ 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)