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Tsirkin" , Stefan Hajnoczi , Hanna Reitz , pkrempa@redhat.com, John Snow Subject: [PATCH v2 06/13] virtio-scsi: protect events_dropped field Date: Tue, 11 Mar 2025 18:11:38 +0800 Message-ID: <20250311101145.1037388-7-stefanha@redhat.com> In-Reply-To: <20250311101145.1037388-1-stefanha@redhat.com> References: <20250311101145.1037388-1-stefanha@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass client-ip=170.10.129.124; envelope-from=stefanha@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org 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 Reviewed-by: Kevin Wolf --- include/hw/virtio/virtio-scsi.h | 3 ++- hw/scsi/virtio-scsi.c | 29 ++++++++++++++++++++--------- 2 files changed, 22 insertions(+), 10 deletions(-) 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 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, };