This Linux kernel change "io_uring: remove unnecessary barrier after updating SQ head" is included in the Linux 5.1 release. This change is authored by Stefan Bühler <source [at] stbuehler.de> on Wed Apr 24 23:54:19 2019 +0200. The commit for this change in Linux stable tree is 9e4c15a (patch).
io_uring: remove unnecessary barrier after updating SQ head There is no operation afterwards to order with. Signed-off-by: Stefan Bühler <[email protected]> Signed-off-by: Jens Axboe <[email protected]>
There are 6 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.
fs/io_uring.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 3671a65..d3c57ee 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -1798,12 +1798,6 @@ static void io_commit_sqring(struct io_ring_ctx *ctx) * write new data to them. */ smp_store_release(&ring->r.head, ctx->cached_sq_head); - - /* - * write side barrier of head update, app has read side. See - * comment at the top of this file - */ - smp_wmb(); } }