This Linux kernel change "io_uring: remove unnecessary barrier after incrementing dropped counter" is included in the Linux 5.1 release. This change is authored by Stefan Bühler <source [at] stbuehler.de> on Wed Apr 24 23:54:21 2019 +0200. The commit for this change in Linux stable tree is b841f19 (patch).
io_uring: remove unnecessary barrier after incrementing dropped counter smp_store_release in io_commit_sqring already orders the store to dropped before the update to SQ head. Signed-off-by: Stefan Bühler <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
There are 2 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.
fs/io_uring.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 662f1c0..2ebc33c 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1846,8 +1846,6 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s) /* drop invalid entries */ ctx->cached_sq_head++; ring->dropped++; - /* See comment at the top of this file */ - smp_wmb(); return false; }