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Tsirkin" , =?UTF-8?q?Philippe=20Mathieu-Daud=C3=A9?= , Stefan Hajnoczi , Kevin Wolf , pkrempa@redhat.com, Fam Zheng , , David Hildenbrand , Peter Xu , Hanna Reitz Subject: [PATCH v4 06/13] virtio-scsi: protect events_dropped field Date: Tue, 11 Mar 2025 21:26:09 +0800 Message-ID: <20250311132616.1049687-7-stefanha@redhat.com> In-Reply-To: <20250311132616.1049687-1-stefanha@redhat.com> References: <20250311132616.1049687-1-stefanha@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=170.10.133.124; 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_H2=0.001, RCVD_IN_VALIDITY_CERTIFIED_BLOCKED=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, SPF_HELO_NONE=0.001, T_SPF_TEMPERROR=0.01 autolearn=unavailable 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @redhat.com) X-ZM-MESSAGEID: 1741699769578019000 Content-Type: text/plain; charset="utf-8" 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-scs= i.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 { =20 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; =20 QemuMutex ctrl_lock; /* protects ctrl_vq */ - QemuMutex event_lock; /* protects event_vq */ =20 /* * 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) =20 vs->sense_size =3D VIRTIO_SCSI_SENSE_DEFAULT_SIZE; vs->cdb_size =3D VIRTIO_SCSI_CDB_DEFAULT_SIZE; - s->events_dropped =3D false; + + WITH_QEMU_LOCK_GUARD(&s->event_lock) { + s->events_dropped =3D false; + } } =20 typedef struct { @@ -978,14 +981,16 @@ static void virtio_scsi_push_event(VirtIOSCSI *s, } =20 req =3D virtio_scsi_pop_req(s, vs->event_vq, &s->event_lock); - if (!req) { - s->events_dropped =3D true; - return; - } + WITH_QEMU_LOCK_GUARD(&s->event_lock) { + if (!req) { + s->events_dropped =3D true; + return; + } =20 - if (s->events_dropped) { - event |=3D VIRTIO_SCSI_T_EVENTS_MISSED; - s->events_dropped =3D false; + if (s->events_dropped) { + event |=3D VIRTIO_SCSI_T_EVENTS_MISSED; + s->events_dropped =3D false; + } } =20 if (virtio_scsi_parse_req(req, 0, sizeof(VirtIOSCSIEvent))) { @@ -1014,7 +1019,13 @@ static void virtio_scsi_push_event(VirtIOSCSI *s, =20 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 =3D s->events_dropped; + } + + if (events_dropped) { VirtIOSCSIEventInfo info =3D { .event =3D VIRTIO_SCSI_T_NO_EVENT, }; --=20 2.48.1