From 773d1bb4e9ea9ca704372e52569955937f91f15c Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Eugenio=20P=C3=A9rez?= Date: Tue, 23 Aug 2022 20:30:28 +0200 Subject: [PATCH 13/23] vhost: Delete useless read memory barrier MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RH-Author: Eugenio Pérez RH-MergeRequest: 116: vdpa: Restore device state on destination RH-Bugzilla: 2114060 RH-Acked-by: Cindy Lu RH-Acked-by: Miroslav Rezanina RH-Commit: [12/21] 0e238fe934b1fc2c7e10b6f693468bc25ea3243f (eperezmartin/qemu-kvm) Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2114060 Upstream status: git@github.com:jasowang/qemu.git net-next As discussed in previous series [1], this memory barrier is useless with the atomic read of used idx at vhost_svq_more_used. Deleting it. [1] https://lists.nongnu.org/archive/html/qemu-devel/2022-07/msg02616.html Signed-off-by: Eugenio Pérez Acked-by: Jason Wang Signed-off-by: Jason Wang (cherry picked from commit cdfb1612ba0f9b76367c96ce26ba94fedc7a0e61) --- hw/virtio/vhost-shadow-virtqueue.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/hw/virtio/vhost-shadow-virtqueue.c b/hw/virtio/vhost-shadow-virtqueue.c index 7792f3db1d..d36afbc547 100644 --- a/hw/virtio/vhost-shadow-virtqueue.c +++ b/hw/virtio/vhost-shadow-virtqueue.c @@ -509,9 +509,6 @@ size_t vhost_svq_poll(VhostShadowVirtqueue *svq) if (unlikely(g_get_monotonic_time() - start_us > 10e6)) { return 0; } - - /* Make sure we read new used_idx */ - smp_rmb(); } while (true); } -- 2.31.1