Commit 7d8ab5b2f7 for qemu.org
commit 7d8ab5b2f77d84a21dbeb5b254e26320e1943af4
Author: Stefan Hajnoczi <stefanha@redhat.com>
Date: Tue Mar 11 21:26:09 2025 +0800
virtio-scsi: protect events_dropped field
The block layer can invoke the resize callback from any AioContext that
is processing requests. The virtqueue is already protected but the
events_dropped field also needs to be protected against races. Cover it
using the event virtqueue lock because it is closely associated with
accesses to the virtqueue.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Message-ID: <20250311132616.1049687-7-stefanha@redhat.com>
Tested-by: Peter Krempa <pkrempa@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c
index 073ccd3d5b..2d796a861b 100644
--- a/hw/scsi/virtio-scsi.c
+++ b/hw/scsi/virtio-scsi.c
@@ -948,7 +948,10 @@ static void virtio_scsi_reset(VirtIODevice *vdev)
vs->sense_size = VIRTIO_SCSI_SENSE_DEFAULT_SIZE;
vs->cdb_size = VIRTIO_SCSI_CDB_DEFAULT_SIZE;
- s->events_dropped = false;
+
+ WITH_QEMU_LOCK_GUARD(&s->event_lock) {
+ s->events_dropped = false;
+ }
}
typedef struct {
@@ -978,14 +981,16 @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
}
req = virtio_scsi_pop_req(s, vs->event_vq, &s->event_lock);
- if (!req) {
- s->events_dropped = true;
- return;
- }
+ WITH_QEMU_LOCK_GUARD(&s->event_lock) {
+ if (!req) {
+ s->events_dropped = true;
+ return;
+ }
- if (s->events_dropped) {
- event |= VIRTIO_SCSI_T_EVENTS_MISSED;
- s->events_dropped = false;
+ if (s->events_dropped) {
+ event |= VIRTIO_SCSI_T_EVENTS_MISSED;
+ s->events_dropped = false;
+ }
}
if (virtio_scsi_parse_req(req, 0, sizeof(VirtIOSCSIEvent))) {
@@ -1014,7 +1019,13 @@ static void virtio_scsi_push_event(VirtIOSCSI *s,
static void virtio_scsi_handle_event_vq(VirtIOSCSI *s, VirtQueue *vq)
{
- if (s->events_dropped) {
+ bool events_dropped;
+
+ WITH_QEMU_LOCK_GUARD(&s->event_lock) {
+ events_dropped = s->events_dropped;
+ }
+
+ if (events_dropped) {
VirtIOSCSIEventInfo info = {
.event = VIRTIO_SCSI_T_NO_EVENT,
};
diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h
index 4ee98ebf63..7b7e3ced7a 100644
--- a/include/hw/virtio/virtio-scsi.h
+++ b/include/hw/virtio/virtio-scsi.h
@@ -82,10 +82,11 @@ struct VirtIOSCSI {
SCSIBus bus;
int resetting; /* written from main loop thread, read from any thread */
+
+ QemuMutex event_lock; /* protects event_vq and events_dropped */
bool events_dropped;
QemuMutex ctrl_lock; /* protects ctrl_vq */
- QemuMutex event_lock; /* protects event_vq */
/*
* TMFs deferred to main loop BH. These fields are protected by