qemu-kvm/SOURCES/kvm-virtio-scsi-don-t-lock-AioContext-around-virtio_queu.patch

59 lines
2.1 KiB
Diff

From 1ee3f919a51135a0798a14c734ca80d74d30025d Mon Sep 17 00:00:00 2001
From: Stefan Hajnoczi <stefanha@redhat.com>
Date: Mon, 4 Dec 2023 11:42:57 -0500
Subject: [PATCH 078/101] virtio-scsi: don't lock AioContext around
virtio_queue_aio_attach_host_notifier()
RH-Author: Kevin Wolf <kwolf@redhat.com>
RH-MergeRequest: 214: Remove AioContext lock
RH-Jira: RHEL-15965
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Commit: [9/26] 5e1179e617d05bf765b285ba42393ec1ddbeba28 (kmwolf/centos-qemu-kvm)
virtio_queue_aio_attach_host_notifier() does not require the AioContext
lock. Stop taking the lock and add an explicit smp_wmb() because we were
relying on the implicit barrier in the AioContext lock before.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20231204164259.1515217-3-stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
hw/scsi/virtio-scsi-dataplane.c | 8 +-------
1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/hw/scsi/virtio-scsi-dataplane.c b/hw/scsi/virtio-scsi-dataplane.c
index 1e684beebe..135e23fe54 100644
--- a/hw/scsi/virtio-scsi-dataplane.c
+++ b/hw/scsi/virtio-scsi-dataplane.c
@@ -149,23 +149,17 @@ int virtio_scsi_dataplane_start(VirtIODevice *vdev)
memory_region_transaction_commit();
- /*
- * These fields are visible to the IOThread so we rely on implicit barriers
- * in aio_context_acquire() on the write side and aio_notify_accept() on
- * the read side.
- */
s->dataplane_starting = false;
s->dataplane_started = true;
+ smp_wmb(); /* paired with aio_notify_accept() */
if (s->bus.drain_count == 0) {
- aio_context_acquire(s->ctx);
virtio_queue_aio_attach_host_notifier(vs->ctrl_vq, s->ctx);
virtio_queue_aio_attach_host_notifier_no_poll(vs->event_vq, s->ctx);
for (i = 0; i < vs->conf.num_queues; i++) {
virtio_queue_aio_attach_host_notifier(vs->cmd_vqs[i], s->ctx);
}
- aio_context_release(s->ctx);
}
return 0;
--
2.39.3