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bh=AJdV4X+lnavj8ZoIfgg+Z3J0O/lFFA5Rp1W5gL/hrq4=; b=ZA8zhPTmS8Cg9f2b/uQ0ZTWK9fEVrRvNsr6BUG4i485c9uIbVPG/jyfSFE3fd4YJVdB00F Kp9mEBrJgoumZvLNNDNsRPmrjkEbcVk1ypyVOFSpHFH1kD9xpHEvkY1TVxk9RuN7Kdp9ea oFBwGsMedPb6JI1Ft9/KIC6qTzI572I= X-MC-Unique: dTa05JIHNlyxtJU5vJZirg-1 From: Kevin Wolf To: qemu-block@nongnu.org Cc: kwolf@redhat.com, stefanha@redhat.com, qemu-devel@nongnu.org Subject: [PULL 05/33] virtio-blk: add lock to protect s->rq Date: Thu, 21 Dec 2023 22:23:10 +0100 Message-ID: <20231221212339.164439-6-kwolf@redhat.com> In-Reply-To: <20231221212339.164439-1-kwolf@redhat.com> References: <20231221212339.164439-1-kwolf@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.8 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=kwolf@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.061, 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_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-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: 1703194105714100001 Content-Type: text/plain; charset="utf-8" From: Stefan Hajnoczi s->rq is accessed from IO_CODE and GLOBAL_STATE_CODE. Introduce a lock to protect s->rq and eliminate reliance on the AioContext lock. Signed-off-by: Stefan Hajnoczi Message-ID: <20230914140101.1065008-3-stefanha@redhat.com> Reviewed-by: Kevin Wolf Reviewed-by: Eric Blake Reviewed-by: Michael S. Tsirkin Signed-off-by: Kevin Wolf --- include/hw/virtio/virtio-blk.h | 3 +- hw/block/virtio-blk.c | 67 +++++++++++++++++++++++----------- 2 files changed, 47 insertions(+), 23 deletions(-) diff --git a/include/hw/virtio/virtio-blk.h b/include/hw/virtio/virtio-blk.h index dafec432ce..9881009c22 100644 --- a/include/hw/virtio/virtio-blk.h +++ b/include/hw/virtio/virtio-blk.h @@ -54,7 +54,8 @@ struct VirtIOBlockReq; struct VirtIOBlock { VirtIODevice parent_obj; BlockBackend *blk; - void *rq; + QemuMutex rq_lock; + void *rq; /* protected by rq_lock */ VirtIOBlkConf conf; unsigned short sector_mask; bool original_wce; diff --git a/hw/block/virtio-blk.c b/hw/block/virtio-blk.c index a1f8e15522..ee38e089bc 100644 --- a/hw/block/virtio-blk.c +++ b/hw/block/virtio-blk.c @@ -82,8 +82,11 @@ static int virtio_blk_handle_rw_error(VirtIOBlockReq *re= q, int error, /* Break the link as the next request is going to be parsed from t= he * ring again. Otherwise we may end up doing a double completion! = */ req->mr_next =3D NULL; - req->next =3D s->rq; - s->rq =3D req; + + WITH_QEMU_LOCK_GUARD(&s->rq_lock) { + req->next =3D s->rq; + s->rq =3D req; + } } else if (action =3D=3D BLOCK_ERROR_ACTION_REPORT) { virtio_blk_req_complete(req, VIRTIO_BLK_S_IOERR); if (acct_failed) { @@ -1183,10 +1186,13 @@ static void virtio_blk_dma_restart_bh(void *opaque) { VirtIOBlock *s =3D opaque; =20 - VirtIOBlockReq *req =3D s->rq; + VirtIOBlockReq *req; MultiReqBuffer mrb =3D {}; =20 - s->rq =3D NULL; + WITH_QEMU_LOCK_GUARD(&s->rq_lock) { + req =3D s->rq; + s->rq =3D NULL; + } =20 aio_context_acquire(blk_get_aio_context(s->conf.conf.blk)); while (req) { @@ -1238,22 +1244,29 @@ static void virtio_blk_reset(VirtIODevice *vdev) AioContext *ctx; VirtIOBlockReq *req; =20 + /* Dataplane has stopped... */ + assert(!s->dataplane_started); + + /* ...but requests may still be in flight. */ ctx =3D blk_get_aio_context(s->blk); aio_context_acquire(ctx); blk_drain(s->blk); + aio_context_release(ctx); =20 /* We drop queued requests after blk_drain() because blk_drain() itsel= f can * produce them. */ - while (s->rq) { - req =3D s->rq; - s->rq =3D req->next; - virtqueue_detach_element(req->vq, &req->elem, 0); - virtio_blk_free_request(req); - } + WITH_QEMU_LOCK_GUARD(&s->rq_lock) { + while (s->rq) { + req =3D s->rq; + s->rq =3D req->next; =20 - aio_context_release(ctx); + /* No other threads can access req->vq here */ + virtqueue_detach_element(req->vq, &req->elem, 0); + + virtio_blk_free_request(req); + } + } =20 - assert(!s->dataplane_started); blk_set_enable_write_cache(s->blk, s->original_wce); } =20 @@ -1443,18 +1456,22 @@ static void virtio_blk_set_status(VirtIODevice *vde= v, uint8_t status) static void virtio_blk_save_device(VirtIODevice *vdev, QEMUFile *f) { VirtIOBlock *s =3D VIRTIO_BLK(vdev); - VirtIOBlockReq *req =3D s->rq; =20 - while (req) { - qemu_put_sbyte(f, 1); + WITH_QEMU_LOCK_GUARD(&s->rq_lock) { + VirtIOBlockReq *req =3D s->rq; =20 - if (s->conf.num_queues > 1) { - qemu_put_be32(f, virtio_get_queue_index(req->vq)); - } + while (req) { + qemu_put_sbyte(f, 1); =20 - qemu_put_virtqueue_element(vdev, f, &req->elem); - req =3D req->next; + if (s->conf.num_queues > 1) { + qemu_put_be32(f, virtio_get_queue_index(req->vq)); + } + + qemu_put_virtqueue_element(vdev, f, &req->elem); + req =3D req->next; + } } + qemu_put_sbyte(f, 0); } =20 @@ -1480,8 +1497,11 @@ static int virtio_blk_load_device(VirtIODevice *vdev= , QEMUFile *f, =20 req =3D qemu_get_virtqueue_element(vdev, f, sizeof(VirtIOBlockReq)= ); virtio_blk_init_request(s, virtio_get_queue(vdev, vq_idx), req); - req->next =3D s->rq; - s->rq =3D req; + + WITH_QEMU_LOCK_GUARD(&s->rq_lock) { + req->next =3D s->rq; + s->rq =3D req; + } } =20 return 0; @@ -1628,6 +1648,8 @@ static void virtio_blk_device_realize(DeviceState *de= v, Error **errp) s->host_features); virtio_init(vdev, VIRTIO_ID_BLOCK, s->config_size); =20 + qemu_mutex_init(&s->rq_lock); + s->blk =3D conf->conf.blk; s->rq =3D NULL; s->sector_mask =3D (s->conf.conf.logical_block_size / BDRV_SECTOR_SIZE= ) - 1; @@ -1679,6 +1701,7 @@ static void virtio_blk_device_unrealize(DeviceState *= dev) virtio_del_queue(vdev, i); } qemu_coroutine_dec_pool_size(conf->num_queues * conf->queue_size / 2); + qemu_mutex_destroy(&s->rq_lock); blk_ram_registrar_destroy(&s->blk_ram_registrar); qemu_del_vm_change_state_handler(s->change); blockdev_mark_auto_del(s->blk); --=20 2.43.0