remoteproc: fix recovery procedure

Commit 7e83cab824a87e83cab824a8 ("remoteproc: Modify recovery path
to use rproc_{start,stop}()") replaces rproc_{shutdown,boot}() with
rproc_{stop,start}(), which skips destroy the virtio device at stop
but re-initializes it again at start.

Issue is that struct virtio_dev is not correctly reinitialized like done
at initial allocation thanks to kzalloc() and kobject is considered as
already initialized by kernel. That is due to the fact struct virtio_dev
is allocated and released at vdev resource handling level managed and
virtio device is registered and unregistered at rproc subdevices level.

Moreover kernel documentation mentions that device struct must be
zero initialized before calling device_initialize().

This patch disentangles struct virtio_dev from struct rproc_vdev as
the two struct don't have the same life-cycle.

struct virtio_dev is now allocated on rproc_start() and released
on rproc_stop().

This patch applies on top of patch
remoteproc: create vdev subdevice with specific dma memory pool [1]

[1]: https://patchwork.kernel.org/patch/10755781/

Fixes: 7e83cab8 ("remoteproc: Modify recovery path to use rproc_{start,stop}()")
Reported-by: Xiang Xiao <xiaoxiang781216@gmail.com>
Signed-off-by: Loic Pallardy <loic.pallardy@st.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/remoteproc_core.c

@@ -421,8 +421,11 @@ static int rproc_vdev_do_start(struct rproc_subdev *subdev)
 static void rproc_vdev_do_stop(struct rproc_subdev *subdev, bool crashed)
 {
 	struct rproc_vdev *rvdev = container_of(subdev, struct rproc_vdev, subdev);
+	int ret;
 
-	rproc_remove_virtio_dev(rvdev);
+	ret = device_for_each_child(&rvdev->dev, NULL, rproc_remove_virtio_dev);
+	if (ret)
+		dev_warn(&rvdev->dev, "can't remove vdev child device: %d\n", ret);
 }
 
 /**

drivers/remoteproc/remoteproc_internal.h

@@ -32,7 +32,7 @@ void rproc_vdev_release(struct kref *ref);
 
 /* from remoteproc_virtio.c */
 int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id);
-void rproc_remove_virtio_dev(struct rproc_vdev *rvdev);
+int rproc_remove_virtio_dev(struct device *dev, void *data);
 
 /* from remoteproc_debugfs.c */
 void rproc_remove_trace_file(struct dentry *tfile);

drivers/remoteproc/remoteproc_virtio.c

@@ -313,6 +313,8 @@ static void rproc_virtio_dev_release(struct device *dev)
 	struct rproc_vdev *rvdev = vdev_to_rvdev(vdev);
 	struct rproc *rproc = vdev_to_rproc(vdev);
 
+	kfree(vdev);
+
 	kref_put(&rvdev->refcount, rproc_vdev_release);
 
 	put_device(&rproc->dev);
@@ -331,7 +333,7 @@ int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
 {
 	struct rproc *rproc = rvdev->rproc;
 	struct device *dev = &rvdev->dev;
-	struct virtio_device *vdev = &rvdev->vdev;
+	struct virtio_device *vdev;
 	struct rproc_mem_entry *mem;
 	int ret;
 
@@ -372,6 +374,12 @@ int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
 		}
 	}
 
+	/* Allocate virtio device */
+	vdev = kzalloc(sizeof(*vdev), GFP_KERNEL);
+	if (!vdev) {
+		ret = -ENOMEM;
+		goto out;
+	}
 	vdev->id.device	= id,
 	vdev->config = &rproc_virtio_config_ops,
 	vdev->dev.parent = dev;
@@ -405,11 +413,15 @@ int rproc_add_virtio_dev(struct rproc_vdev *rvdev, int id)
 
 /**
  * rproc_remove_virtio_dev() - remove an rproc-induced virtio device
- * @rvdev: the remote vdev
+ * @dev: the virtio device
+ * @data: must be null
  *
  * This function unregisters an existing virtio device.
  */
-void rproc_remove_virtio_dev(struct rproc_vdev *rvdev)
+int rproc_remove_virtio_dev(struct device *dev, void *data)
 {
-	unregister_virtio_device(&rvdev->vdev);
+	struct virtio_device *vdev = dev_to_virtio(dev);
+
+	unregister_virtio_device(vdev);
+	return 0;
 }

include/linux/remoteproc.h

@@ -559,7 +559,6 @@ struct rproc_vdev {
 	unsigned int id;
 	struct list_head node;
 	struct rproc *rproc;
-	struct virtio_device vdev;
 	struct rproc_vring vring[RVDEV_NUM_VRINGS];
 	u32 rsc_offset;
 	u32 index;
@@ -602,7 +601,7 @@ int rproc_coredump_add_custom_segment(struct rproc *rproc,
 
 static inline struct rproc_vdev *vdev_to_rvdev(struct virtio_device *vdev)
 {
-	return container_of(vdev, struct rproc_vdev, vdev);
+	return container_of(vdev->dev.parent, struct rproc_vdev, dev);
 }
 
 static inline struct rproc *vdev_to_rproc(struct virtio_device *vdev)