From:   Mike Christie <michael.christie@oracle.com>
To:     geert@linux-m68k.org, vverma@digitalocean.com, hdanton@sina.com,
        hch@infradead.org, stefanha@redhat.com, jasowang@redhat.com,
        mst@redhat.com, sgarzare@redhat.com,
        virtualization@lists.linux-foundation.org,
        christian.brauner@ubuntu.com, axboe@kernel.dk,
        linux-kernel@vger.kernel.org
Cc:     Mike Christie <michael.christie@oracle.com>,
        Christoph Hellwig <hch@lst.de>
Subject: [PATCH V5 09/10] vhost: move worker thread fields to new struct
Date:   Sun, 21 Nov 2021 11:49:29 -0600
Message-Id: <20211121174930.6690-10-michael.christie@oracle.com>
In-Reply-To: <20211121174930.6690-1-michael.christie@oracle.com>
References: <20211121174930.6690-1-michael.christie@oracle.com>
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?8rpQZKURbuoOUhTPoj1GvR9tzbA6OV1ZJx+OlJ1wjeVssqmvHJfrWSBrDvAb?=
 =?us-ascii?Q?rTHED0KCJ8SHe2JQdw6yy8ZDoAbGM7oo5sdhEa63OIMeihn2wdhy4FgdSiXz?=
 =?us-ascii?Q?hiJ6J6R8dEfGJ+Pid2X5/icnWG/EsalTcMJqQh4+8lVDl/Rhv3TjoVO7TO4F?=
 =?us-ascii?Q?IM/anmYSrEB7lG5N7tvdKIY/k1THvlC3TvTt4fGOc1LL4FbrVdoAwQ5Sdyu4?=
 =?us-ascii?Q?2VgB09BkkQkRMBHHHmVK5v42Mkfb6sgWiajwen/eRgU00P+h+zDRg0uDCxRV?=
 =?us-ascii?Q?iu3SoMV3SiNQASWTsQz9/H4DoJb/QYyh6fSTPfgDUb0Wd213KsdUyjBKWioI?=
 =?us-ascii?Q?EA0jabhqXOmGfOBCR3A+Mj4pxBg50PaPmosqxwLumVzJNHcFt2YLUiJMz79e?=
 =?us-ascii?Q?5kRwBJeR0nzFK6aOlwWPIx1VZ114Ux1uZOUDBIQH6YJIGGrcT2umlObdauMO?=
 =?us-ascii?Q?P2YX6Gj5VGDS6WPDPacDWaa6/5OnduorLpGKUFOCULelmZwi96NQ7aEZYh3s?=
 =?us-ascii?Q?2zuFcVRzeJUySco5zR/oAv6X6u07W2YL6HGNsXwyUKJTIOVK42LoVrNKr1WV?=
 =?us-ascii?Q?U35EY+vQcOcURNLUDIyURMqhC29FYHoz2udyw+hfYmHMrkpCIAwJ34kTCCEU?=
 =?us-ascii?Q?bdgKaEtV2Fx/uBGTLH14hAnjIaZIvGnBHMawi+HW2WSttgdjDvZ41LFzCwvz?=
 =?us-ascii?Q?U2L98H5PiyuP9cVoR0bpdT2n7/sCb2PTbXQDY4ITkEnwgrtxIqoyyl7MxB6v?=
 =?us-ascii?Q?faHCy3eAk7dNrcm/HjF+UdQu7+pCyUHbnMbS88UhPT8U4C4SZutJtFPGDNa2?=
 =?us-ascii?Q?SKMEG+vLTBQiXCpYjTvtaGGg4eyF3UKdliDz8SBpafORSAuPHZZCqIDi9ciG?=
 =?us-ascii?Q?vVU4NdozzocNS81Q6Spy3G5WEOGqtuaVYpOrmYwLzE/wgOKp4IssoFTwy7n/?=
 =?us-ascii?Q?OwX65/vwZqpogo0SgxtbOQIKbRXW5kC3GPj8DewMTjZJMYSQvzIL92e1/3zD?=
 =?us-ascii?Q?AFmXt0C7Opec8oRRZIZeCK16rjZD/uE8H1YrFt/djDf5WeGqcPPhS1NHrQ2p?=
 =?us-ascii?Q?MER0BJ5RL0RivGbbI5Xi3jY6qxk4YCE0LF2q1qMtBJrjdADL2/7AOYj/Svgh?=
 =?us-ascii?Q?uELeVQR9I6xYYgzWF71uGv1aZbDS3y9l5DIX1wtwkOoNgPHmWC9ovIwjaVvK?=
 =?us-ascii?Q?bRIUm1yW5lCo6PcMicrwVK9QfjM07eBDzxaXeusMj0mXMR2TP1hs1PJYbbrP?=
 =?us-ascii?Q?a+pUkY1QWIYRTgPWRRgMPnQWJmsFN05UqMz2ZGdI1zTncIFABtC9ig1Mzrh6?=
 =?us-ascii?Q?4bk/BkU0NF8UiNPE4eR+4vWLIYUFEmZu4as5M41cqL7EMNOdCo6/AYKOVuD8?=
 =?us-ascii?Q?ibbEDiDQDLu40unMT6c4Gu2/IxfsmzjbocmM2uoh2jdY/LKPUP4Y7XNdNsH1?=
 =?us-ascii?Q?uOgWGpHS5WWpJR3YCPCpDdkiKnvBVJ2tyoTgaWv6nCWW/pHig7Kmgt9S+KsF?=
 =?us-ascii?Q?9piuzXi8UhoJYjakce3H+n5Ss7mFgEnrN4oWhKEtx+NSPnd23b3jTsqhxOkg?=
 =?us-ascii?Q?DwCVSCh5LzDwe2SGpO1qdfeg6I8XI7OSPTq1yGskTFCFSLbu2JuuCT9evRka?=
 =?us-ascii?Q?FFXgalMKoYYHVX4nkHQKWbVoLQ+OwmhUJb6QxChD6LckS+Kf4HMYSnRCCKL0?=
 =?us-ascii?Q?pc7lNg=3D=3D?=
X-OriginatorOrg: oracle.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 3dce21d8-7912-41aa-a523-08d9ad17513f
X-MS-Exchange-CrossTenant-AuthSource: DM5PR10MB1466.namprd10.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 21 Nov 2021 17:49:50.9953
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 4e2c6054-71cb-48f1-bd6c-3a9705aca71b
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: BL2GvSJmm3NI8VDW/NYbj4FMO36G4WnhnHvMmKuTm9yUimqCo0ZOZldWyTrQhamb2zRC9e5an5Lywcwzq8k759nxATfxHZK3MoG4Zggq10c=
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR10MB5055
X-Proofpoint-Virus-Version: vendor=nai engine=6300 definitions=10175 signatures=668683
X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 mlxscore=0 spamscore=0
 mlxlogscore=999 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0
 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000
 definitions=main-2111210110
X-Proofpoint-GUID: lrBnqrT98DvN2Ob9Oe_P2qg-l6jurr-Y
X-Proofpoint-ORIG-GUID: lrBnqrT98DvN2Ob9Oe_P2qg-l6jurr-Y
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

This is just a prep patch. It moves the worker related fields to a new
vhost_worker struct and moves the code around to create some helpers that
will be used in the next patch.

Signed-off-by: Mike Christie <michael.christie@oracle.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 drivers/vhost/vhost.c | 98 ++++++++++++++++++++++++++++---------------
 drivers/vhost/vhost.h | 11 +++--
 2 files changed, 72 insertions(+), 37 deletions(-)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 59edb5a1ffe2..c9a1f706989c 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -263,8 +263,8 @@ void vhost_work_queue(struct vhost_dev *dev, struct vhost_work *work)
 		 * sure it was not in the list.
 		 * test_and_set_bit() implies a memory barrier.
 		 */
-		llist_add(&work->node, &dev->work_list);
-		wake_up_process(dev->worker);
+		llist_add(&work->node, &dev->worker->work_list);
+		wake_up_process(dev->worker->task);
 	}
 }
 EXPORT_SYMBOL_GPL(vhost_work_queue);
@@ -272,7 +272,7 @@ EXPORT_SYMBOL_GPL(vhost_work_queue);
 /* A lockless hint for busy polling code to exit the loop */
 bool vhost_has_work(struct vhost_dev *dev)
 {
-	return !llist_empty(&dev->work_list);
+	return dev->worker && !llist_empty(&dev->worker->work_list);
 }
 EXPORT_SYMBOL_GPL(vhost_has_work);
 
@@ -343,7 +343,8 @@ static void vhost_vq_reset(struct vhost_dev *dev,
 
 static int vhost_worker(void *data)
 {
-	struct vhost_dev *dev = data;
+	struct vhost_worker *worker = data;
+	struct vhost_dev *dev = worker->dev;
 	struct vhost_work *work, *work_next;
 	struct llist_node *node;
 
@@ -358,7 +359,7 @@ static int vhost_worker(void *data)
 			break;
 		}
 
-		node = llist_del_all(&dev->work_list);
+		node = llist_del_all(&worker->work_list);
 		if (!node)
 			schedule();
 
@@ -368,7 +369,7 @@ static int vhost_worker(void *data)
 		llist_for_each_entry_safe(work, work_next, node, node) {
 			clear_bit(VHOST_WORK_QUEUED, &work->flags);
 			__set_current_state(TASK_RUNNING);
-			kcov_remote_start_common(dev->kcov_handle);
+			kcov_remote_start_common(worker->kcov_handle);
 			work->fn(work);
 			kcov_remote_stop();
 			if (need_resched())
@@ -487,7 +488,6 @@ void vhost_dev_init(struct vhost_dev *dev,
 	dev->byte_weight = byte_weight;
 	dev->use_worker = use_worker;
 	dev->msg_handler = msg_handler;
-	init_llist_head(&dev->work_list);
 	init_waitqueue_head(&dev->wait);
 	INIT_LIST_HEAD(&dev->read_list);
 	INIT_LIST_HEAD(&dev->pending_list);
@@ -579,10 +579,60 @@ static void vhost_detach_mm(struct vhost_dev *dev)
 	dev->mm = NULL;
 }
 
+static void vhost_worker_free(struct vhost_dev *dev)
+{
+	struct vhost_worker *worker = dev->worker;
+
+	if (!worker)
+		return;
+
+	dev->worker = NULL;
+	WARN_ON(!llist_empty(&worker->work_list));
+	kthread_stop(worker->task);
+	kfree(worker);
+}
+
+static int vhost_worker_create(struct vhost_dev *dev)
+{
+	struct vhost_worker *worker;
+	struct task_struct *task;
+	int ret;
+
+	worker = kzalloc(sizeof(*worker), GFP_KERNEL_ACCOUNT);
+	if (!worker)
+		return -ENOMEM;
+
+	dev->worker = worker;
+	worker->dev = dev;
+	worker->kcov_handle = kcov_common_handle();
+	init_llist_head(&worker->work_list);
+
+	task = kthread_create(vhost_worker, worker, "vhost-%d", current->pid);
+	if (IS_ERR(task)) {
+		ret = PTR_ERR(task);
+		goto free_worker;
+	}
+
+	worker->task = task;
+	wake_up_process(task); /* avoid contributing to loadavg */
+
+	ret = vhost_attach_cgroups(dev);
+	if (ret)
+		goto stop_worker;
+
+	return 0;
+
+stop_worker:
+	kthread_stop(worker->task);
+free_worker:
+	kfree(worker);
+	dev->worker = NULL;
+	return ret;
+}
+
 /* Caller should have device mutex */
 long vhost_dev_set_owner(struct vhost_dev *dev)
 {
-	struct task_struct *worker;
 	int err;
 
 	/* Is there an owner already? */
@@ -593,36 +643,21 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
 
 	vhost_attach_mm(dev);
 
-	dev->kcov_handle = kcov_common_handle();
 	if (dev->use_worker) {
-		worker = kthread_create(vhost_worker, dev,
-					"vhost-%d", current->pid);
-		if (IS_ERR(worker)) {
-			err = PTR_ERR(worker);
-			goto err_worker;
-		}
-
-		dev->worker = worker;
-		wake_up_process(worker); /* avoid contributing to loadavg */
-
-		err = vhost_attach_cgroups(dev);
+		err = vhost_worker_create(dev);
 		if (err)
-			goto err_cgroup;
+			goto err_worker;
 	}
 
 	err = vhost_dev_alloc_iovecs(dev);
 	if (err)
-		goto err_cgroup;
+		goto err_iovecs;
 
 	return 0;
-err_cgroup:
-	if (dev->worker) {
-		kthread_stop(dev->worker);
-		dev->worker = NULL;
-	}
+err_iovecs:
+	vhost_worker_free(dev);
 err_worker:
 	vhost_detach_mm(dev);
-	dev->kcov_handle = 0;
 err_mm:
 	return err;
 }
@@ -712,12 +747,7 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
 	dev->iotlb = NULL;
 	vhost_clear_msg(dev);
 	wake_up_interruptible_poll(&dev->wait, EPOLLIN | EPOLLRDNORM);
-	WARN_ON(!llist_empty(&dev->work_list));
-	if (dev->worker) {
-		kthread_stop(dev->worker);
-		dev->worker = NULL;
-		dev->kcov_handle = 0;
-	}
+	vhost_worker_free(dev);
 	vhost_detach_mm(dev);
 }
 EXPORT_SYMBOL_GPL(vhost_dev_cleanup);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 638bb640d6b4..102ce25e4e13 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -25,6 +25,13 @@ struct vhost_work {
 	unsigned long		flags;
 };
 
+struct vhost_worker {
+	struct task_struct	*task;
+	struct llist_head	work_list;
+	struct vhost_dev	*dev;
+	u64			kcov_handle;
+};
+
 /* Poll a file (eventfd or socket) */
 /* Note: there's nothing vhost specific about this structure. */
 struct vhost_poll {
@@ -148,8 +155,7 @@ struct vhost_dev {
 	struct vhost_virtqueue **vqs;
 	int nvqs;
 	struct eventfd_ctx *log_ctx;
-	struct llist_head work_list;
-	struct task_struct *worker;
+	struct vhost_worker *worker;
 	struct vhost_iotlb *umem;
 	struct vhost_iotlb *iotlb;
 	spinlock_t iotlb_lock;
@@ -159,7 +165,6 @@ struct vhost_dev {
 	int iov_limit;
 	int weight;
 	int byte_weight;
-	u64 kcov_handle;
 	bool use_worker;
 	int (*msg_handler)(struct vhost_dev *dev,
 			   struct vhost_iotlb_msg *msg);
-- 
2.25.1