Re: [PATCH RFC 3/3] vhost, kcov: collect coverage from vhost_worker

This patch adds kcov_remote_start/kcov_remote_stop annotations to the
vhost_worker function, which is responsible for processing vhost works.
Since vhost_worker is spawned when a vhost device instance is created,
the common kcov handle is used for kcov_remote_start/stop annotations.

Signed-off-by: Andrey Konovalov <redacted>
---
 drivers/vhost/vhost.c | 15 +++++++++++++++
 drivers/vhost/vhost.h |  3 +++
 2 files changed, 18 insertions(+)

diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 36ca2cf419bf..71a349f6b352 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c

@@ -357,7 +357,13 @@ 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);
+#ifdef CONFIG_KCOV
+			kcov_remote_start(dev->kcov_handle);
+#endif

 			work->fn(work);
+#ifdef CONFIG_KCOV
+			kcov_remote_stop();
+#endif
 			if (need_resched())
 				schedule();
 		}

@@ -546,6 +552,9 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
 
 	/* No owner, become one */
 	dev->mm = get_task_mm(current);
+#ifdef CONFIG_KCOV
+	dev->kcov_handle = current->kcov_handle;
+#endif
 	worker = kthread_create(vhost_worker, dev, "vhost-%d", current->pid);
 	if (IS_ERR(worker)) {
 		err = PTR_ERR(worker);

@@ -571,6 +580,9 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
 	if (dev->mm)
 		mmput(dev->mm);
 	dev->mm = NULL;
+#ifdef CONFIG_KCOV
+	dev->kcov_handle = 0;
+#endif
 err_mm:
 	return err;
 }

@@ -682,6 +694,9 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
 	if (dev->worker) {
 		kthread_stop(dev->worker);
 		dev->worker = NULL;
+#ifdef CONFIG_KCOV
+		dev->kcov_handle = 0;
+#endif
 	}
 	if (dev->mm)
 		mmput(dev->mm);

diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index e9ed2722b633..010ca1ebcbd5 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h

@@ -173,6 +173,9 @@ struct vhost_dev {
 	int iov_limit;
 	int weight;
 	int byte_weight;
+#ifdef CONFIG_KCOV
+	u64 kcov_handle;
+#endif