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[79.181.55.232]) by smtp.gmail.com with ESMTPSA id w17sm6177997wra.71.2020.06.09.21.27.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Jun 2020 21:27:52 -0700 (PDT) Date: Wed, 10 Jun 2020 00:27:50 -0400 From: "Michael S. Tsirkin" To: qemu-devel@nongnu.org Subject: [PULL 35/56] vhost-user-blk: delay vhost_user_blk_disconnect Message-ID: <20200610042613.1459309-36-mst@redhat.com> References: <20200610042613.1459309-1-mst@redhat.com> MIME-Version: 1.0 In-Reply-To: <20200610042613.1459309-1-mst@redhat.com> X-Mailer: git-send-email 2.24.1.751.gd10ce2899c X-Mutt-Fcc: =sent X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Disposition: inline Received-SPF: pass client-ip=205.139.110.61; envelope-from=mst@redhat.com; helo=us-smtp-delivery-1.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/06/09 23:51:15 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -30 X-Spam_score: -3.1 X-Spam_bar: --- X-Spam_report: (-3.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-1, 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_H4=-0.01, RCVD_IN_MSPIKE_WL=-0.01, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Peter Maydell , qemu-block@nongnu.org, Max Reitz , Li Feng , Raphael Norwitz , Dima Stepanov Errors-To: qemu-devel-bounces+patchwork-qemu-devel=patchwork.kernel.org@nongnu.org Sender: "Qemu-devel" From: Dima Stepanov A socket write during vhost-user communication may trigger a disconnect event, calling vhost_user_blk_disconnect() and clearing all the vhost_dev structures holding data that vhost-user functions expect to remain valid to roll back initialization correctly. Delay the cleanup to keep vhost_dev structure valid. There are two possible states to handle: 1. RUN_STATE_PRELAUNCH: skip bh oneshot call and perform disconnect in the caller routine. 2. RUN_STATE_RUNNING: delay by using bh BH changes are based on the similar changes for the vhost-user-net device: commit e7c83a885f865128ae3cf1946f8cb538b63cbfba "vhost-user: delay vhost_user_stop" Signed-off-by: Dima Stepanov Message-Id: <69b73b94dcd066065595266c852810e0863a0895.1590396396.git.dimastep@yandex-team.ru> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin Signed-off-by: Li Feng Reviewed-by: Raphael Norwitz --- hw/block/vhost-user-blk.c | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/hw/block/vhost-user-blk.c b/hw/block/vhost-user-blk.c index 9d8c0b3909..76838e76d3 100644 --- a/hw/block/vhost-user-blk.c +++ b/hw/block/vhost-user-blk.c @@ -349,6 +349,19 @@ static void vhost_user_blk_disconnect(DeviceState *dev) vhost_dev_cleanup(&s->dev); } +static void vhost_user_blk_event(void *opaque, QEMUChrEvent event); + +static void vhost_user_blk_chr_closed_bh(void *opaque) +{ + DeviceState *dev = opaque; + VirtIODevice *vdev = VIRTIO_DEVICE(dev); + VHostUserBlk *s = VHOST_USER_BLK(vdev); + + vhost_user_blk_disconnect(dev); + qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, vhost_user_blk_event, + NULL, opaque, NULL, true); +} + static void vhost_user_blk_event(void *opaque, QEMUChrEvent event) { DeviceState *dev = opaque; @@ -363,7 +376,30 @@ static void vhost_user_blk_event(void *opaque, QEMUChrEvent event) } break; case CHR_EVENT_CLOSED: - vhost_user_blk_disconnect(dev); + /* + * A close event may happen during a read/write, but vhost + * code assumes the vhost_dev remains setup, so delay the + * stop & clear. There are two possible paths to hit this + * disconnect event: + * 1. When VM is in the RUN_STATE_PRELAUNCH state. The + * vhost_user_blk_device_realize() is a caller. + * 2. In tha main loop phase after VM start. + * + * For p2 the disconnect event will be delayed. We can't + * do the same for p1, because we are not running the loop + * at this moment. So just skip this step and perform + * disconnect in the caller function. + * + * TODO: maybe it is a good idea to make the same fix + * for other vhost-user devices. + */ + if (runstate_is_running()) { + AioContext *ctx = qemu_get_current_aio_context(); + + qemu_chr_fe_set_handlers(&s->chardev, NULL, NULL, NULL, NULL, + NULL, NULL, false); + aio_bh_schedule_oneshot(ctx, vhost_user_blk_chr_closed_bh, opaque); + } break; case CHR_EVENT_BREAK: case CHR_EVENT_MUX_IN: