Re: [PATCH] rpmsg: add a description field

[Fabien DESSENNE]

Hi Suman,

See my remarks below

BR

Fabien


On 09/08/2019 11:40 PM, Suman Anna wrote:
> From: Ohad Ben-Cohen <ohad@xxxxxxxxxx>
>
> Add a new description field to the rpmsg bus infrastructure
> that can be passed onto the rpmsg client drivers for additional
> information. The current rpmsg bus client drivers need to have
> a fixed id_table for proper matching, this new field can allow
> flexibility for the client drivers (eg: like creating unique
> cdevs).
>
> The description field is published through an enhanced name
> service announcement message structure. The name service
> message processing logic is updated to maintain backward
> compatibility with the previous message structure.
>
> Based on an initial patch from Ohad Ben-Cohen.
>
> Signed-off-by: Ohad Ben-Cohen <ohad@xxxxxxxxxx>
> [s-anna@xxxxxx: forward port, add sysfs documentation, fixup qcom drivers]
> Signed-off-by: Suman Anna <s-anna@xxxxxx>
> [t-kristo@xxxxxx: reworked to support both rpmsg with/without the desc field]
> Signed-off-by: Tero Kristo <t-kristo@xxxxxx>
> ---
>   Documentation/ABI/testing/sysfs-bus-rpmsg | 29 +++++++++++++++
>   drivers/rpmsg/qcom_glink_native.c         |  1 +
>   drivers/rpmsg/qcom_smd.c                  |  1 +


Should not you extend qcom_glink_create_ept() and qcom_smd_create_ept() 
so they compare both 'name' AND 'desc' (just like this is proposed in 
rpmsg_device_match()) ?


>   drivers/rpmsg/rpmsg_char.c                |  1 +
>   drivers/rpmsg/rpmsg_core.c                |  6 ++++
>   drivers/rpmsg/virtio_rpmsg_bus.c          | 44 +++++++++++++++++++----
>   drivers/soc/qcom/wcnss_ctrl.c             |  1 +
>   include/linux/rpmsg.h                     |  4 +++
>   8 files changed, 80 insertions(+), 7 deletions(-)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-rpmsg b/Documentation/ABI/testing/sysfs-bus-rpmsg
> index 990fcc420935..7f1b09ecc64d 100644
> --- a/Documentation/ABI/testing/sysfs-bus-rpmsg
> +++ b/Documentation/ABI/testing/sysfs-bus-rpmsg
> @@ -93,3 +93,32 @@ Description:
>   		This sysfs entry allows the rpmsg driver for a rpmsg device
>   		to be specified which will override standard OF, ID table
>   		and name matching.
> +
> +What:		/sys/bus/rpmsg/devices/.../desc
> +Date:		August 2019
> +KernelVersion:	5.4
> +Contact:	Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
> +Description:
> +		Every rpmsg device is a communication channel with a remote
> +		processor. Channels are identified by a textual name (see
> +		/sys/bus/rpmsg/devices/.../name above) and have a local
> +		("source") rpmsg address, and remote ("destination") rpmsg
> +		address.
> +
> +		A channel is first created when an entity, whether local
> +		or remote, starts listening on it for messages (and is thus
> +		called an rpmsg server). When that happens, a "name service"
> +		announcement is sent to the other processor, in order to let
> +		it know about the creation of the channel (this way remote
> +		clients know they can start sending messages).
> +
> +		The listening entity (or client) which communicates with a
> +		remote processor is referred as rpmsg driver. The rpmsg device
> +		and rpmsg driver are matched based on rpmsg device name (see
> +		/sys/bus/rpmsg/devices/.../name above) and rpmsg driver ID table.
> +
> +		This sysfs entry contains an additional optional description of
> +		the rpmsg device that can be optionally included as part of the
> +		"name service" announcement. This description is then passed on
> +		to the corresponding rpmsg drivers to further distinguish multiple
> +		devices associated with the same rpmsg driver.
> diff --git a/drivers/rpmsg/qcom_glink_native.c b/drivers/rpmsg/qcom_glink_native.c
> index f46c787733e8..cfdabddc15ac 100644
> --- a/drivers/rpmsg/qcom_glink_native.c
> +++ b/drivers/rpmsg/qcom_glink_native.c
> @@ -1456,6 +1456,7 @@ static void qcom_glink_rx_close(struct qcom_glink *glink, unsigned int rcid)
>   		strncpy(chinfo.name, channel->name, sizeof(chinfo.name));
>   		chinfo.src = RPMSG_ADDR_ANY;
>   		chinfo.dst = RPMSG_ADDR_ANY;
> +		chinfo.desc[0] = '\0';
>   
>   		rpmsg_unregister_device(glink->dev, &chinfo);
>   	}
> diff --git a/drivers/rpmsg/qcom_smd.c b/drivers/rpmsg/qcom_smd.c
> index 4abbeea782fa..7cd6b9c47065 100644
> --- a/drivers/rpmsg/qcom_smd.c
> +++ b/drivers/rpmsg/qcom_smd.c
> @@ -1307,6 +1307,7 @@ static void qcom_channel_state_worker(struct work_struct *work)
>   		strncpy(chinfo.name, channel->name, sizeof(chinfo.name));
>   		chinfo.src = RPMSG_ADDR_ANY;
>   		chinfo.dst = RPMSG_ADDR_ANY;
> +		chinfo.desc[0] = '\0';
>   		rpmsg_unregister_device(&edge->dev, &chinfo);
>   		channel->registered = false;
>   		spin_lock_irqsave(&edge->channels_lock, flags);
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index eea5ebbb5119..4bd91445a2fd 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -442,6 +442,7 @@ static long rpmsg_ctrldev_ioctl(struct file *fp, unsigned int cmd,
>   	chinfo.name[RPMSG_NAME_SIZE-1] = '\0';
>   	chinfo.src = eptinfo.src;
>   	chinfo.dst = eptinfo.dst;
> +	chinfo.desc[0] = '\0';
>   
>   	return rpmsg_eptdev_create(ctrldev, chinfo);
>   };


It would be good to add DEVICE_ATTR_RO(desc) / desc_show()


> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
> index ea88fd4e2a6e..334a50425b5c 100644
> --- a/drivers/rpmsg/rpmsg_core.c
> +++ b/drivers/rpmsg/rpmsg_core.c
> @@ -302,6 +302,10 @@ static int rpmsg_device_match(struct device *dev, void *data)
>   	if (strncmp(chinfo->name, rpdev->id.name, RPMSG_NAME_SIZE))
>   		return 0;
>   
> +	if (chinfo->desc && chinfo->desc != rpdev->desc &&


chinfo->desc is defined as 'char desc[RPMSG_NAME_SIZE]', so I do not 
think that you shall check chinfo->desc (can't be NULL)

Did you want to check *chinfo->desc ? (desc differs from '\0')

I can't understand the "chinfo->desc != rpdec->desc" test.


> +	    strncmp(chinfo->desc, rpdev->desc, RPMSG_NAME_SIZE))
> +		return 0;
> +
>   	/* found a match ! */
>   	return 1;
>   }
> @@ -365,6 +369,7 @@ static DEVICE_ATTR_RW(field)
>   
>   /* for more info, see Documentation/ABI/testing/sysfs-bus-rpmsg */
>   rpmsg_show_attr(name, id.name, "%s\n");
> +rpmsg_show_attr(desc, desc, "%s\n");
>   rpmsg_show_attr(src, src, "0x%x\n");
>   rpmsg_show_attr(dst, dst, "0x%x\n");
>   rpmsg_show_attr(announce, announce ? "true" : "false", "%s\n");
> @@ -386,6 +391,7 @@ static DEVICE_ATTR_RO(modalias);
>   
>   static struct attribute *rpmsg_dev_attrs[] = {
>   	&dev_attr_name.attr,
> +	&dev_attr_desc.attr,
>   	&dev_attr_modalias.attr,
>   	&dev_attr_dst.attr,
>   	&dev_attr_src.attr,


What about adding strncpy(desc) in rpmsg_dev_probe() ?


> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
> index 376ebbf880d6..49901582ff0e 100644
> --- a/drivers/rpmsg/virtio_rpmsg_bus.c
> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
> @@ -110,6 +110,23 @@ struct rpmsg_ns_msg {
>   	u32 flags;
>   } __packed;
>   
> +/**
> + * struct rpmsg_ns_msg_ext - dynamic name service announcement message v2
> + * @name: name of remote service that is published
> + * @desc: description of remote service
> + * @addr: address of remote service that is published
> + * @flags: indicates whether service is created or destroyed
> + *
> + * Interchangeable nameservice message with rpmsg_ns_msg. This one has
> + * the addition of the desc field for extra flexibility.
> + */
> +struct rpmsg_ns_msg_ext {
> +	char name[RPMSG_NAME_SIZE];
> +	char desc[RPMSG_NAME_SIZE];


It may be better to use a dedicated value for desc length (#define 
RPMSG_DESC_SIZE).

I also wonder if 32 chars are enough for a (text) description.


> +	u32 addr;
> +	u32 flags;
> +} __packed;
> +
>   /**
>    * enum rpmsg_ns_flags - dynamic name service announcement flags
>    *
> @@ -402,8 +419,9 @@ static struct rpmsg_device *rpmsg_create_channel(struct virtproc_info *vrp,
>   	if (tmp) {
>   		/* decrement the matched device's refcount back */
>   		put_device(tmp);
> -		dev_err(dev, "channel %s:%x:%x already exist\n",
> -				chinfo->name, chinfo->src, chinfo->dst);
> +		dev_err(dev, "channel %s:%s:%x:%x already exist\n",
> +			chinfo->name, chinfo->desc,
> +			chinfo->src, chinfo->dst);
>   		return NULL;
>   	}
>   
> @@ -419,6 +437,7 @@ static struct rpmsg_device *rpmsg_create_channel(struct virtproc_info *vrp,
>   	rpdev->src = chinfo->src;
>   	rpdev->dst = chinfo->dst;
>   	rpdev->ops = &virtio_rpmsg_ops;
> +	strncpy(rpdev->desc, chinfo->desc, RPMSG_NAME_SIZE);
>   
>   	/*
>   	 * rpmsg server channels has predefined local address (for now),
> @@ -816,18 +835,29 @@ static int rpmsg_ns_cb(struct rpmsg_device *rpdev, void *data, int len,
>   		       void *priv, u32 src)
>   {
>   	struct rpmsg_ns_msg *msg = data;
> +	struct rpmsg_ns_msg_ext *msg_ext = data;
>   	struct rpmsg_device *newch;
>   	struct rpmsg_channel_info chinfo;
>   	struct virtproc_info *vrp = priv;
>   	struct device *dev = &vrp->vdev->dev;
>   	int ret;
> +	u32 addr;
> +	u32 flags;
>   
>   #if defined(CONFIG_DYNAMIC_DEBUG)
>   	dynamic_hex_dump("NS announcement: ", DUMP_PREFIX_NONE, 16, 1,
>   			 data, len, true);
>   #endif
>   
> -	if (len != sizeof(*msg)) {
> +	if (len == sizeof(*msg)) {
> +		addr = msg->addr;
> +		flags = msg->flags;
> +		chinfo.desc[0] = '\0';
> +	} else if (len == sizeof(*msg_ext)) {
> +		addr = msg_ext->addr;
> +		flags = msg_ext->flags;
> +		strncpy(chinfo.desc, msg_ext->desc, sizeof(chinfo.desc));
> +	} else if (len != sizeof(*msg)) {


shall be 'else', not 'else if'


>   		dev_err(dev, "malformed ns msg (%d)\n", len);
>   		return -EINVAL;
>   	}
> @@ -847,14 +877,14 @@ static int rpmsg_ns_cb(struct rpmsg_device *rpdev, void *data, int len,
>   	msg->name[RPMSG_NAME_SIZE - 1] = '\0';
>   
>   	dev_info(dev, "%sing channel %s addr 0x%x\n",
> -		 msg->flags & RPMSG_NS_DESTROY ? "destroy" : "creat",
> -		 msg->name, msg->addr);
> +		 flags & RPMSG_NS_DESTROY ? "destroy" : "creat",
> +		 msg->name, addr);
>   
>   	strncpy(chinfo.name, msg->name, sizeof(chinfo.name));
>   	chinfo.src = RPMSG_ADDR_ANY;
> -	chinfo.dst = msg->addr;
> +	chinfo.dst = addr;
>   
> -	if (msg->flags & RPMSG_NS_DESTROY) {
> +	if (flags & RPMSG_NS_DESTROY) {
>   		ret = rpmsg_unregister_device(&vrp->vdev->dev, &chinfo);
>   		if (ret)
>   			dev_err(dev, "rpmsg_destroy_channel failed: %d\n", ret);
> diff --git a/drivers/soc/qcom/wcnss_ctrl.c b/drivers/soc/qcom/wcnss_ctrl.c
> index e5c68051fb17..ad9f28dc13f1 100644
> --- a/drivers/soc/qcom/wcnss_ctrl.c
> +++ b/drivers/soc/qcom/wcnss_ctrl.c
> @@ -276,6 +276,7 @@ struct rpmsg_endpoint *qcom_wcnss_open_channel(void *wcnss, const char *name, rp
>   	strscpy(chinfo.name, name, sizeof(chinfo.name));
>   	chinfo.src = RPMSG_ADDR_ANY;
>   	chinfo.dst = RPMSG_ADDR_ANY;
> +	chinfo.desc[0] = '\0';
>   
>   	return rpmsg_create_ept(_wcnss->channel->rpdev, cb, priv, chinfo);
>   }
> diff --git a/include/linux/rpmsg.h b/include/linux/rpmsg.h
> index 9fe156d1c018..436faf04ba1c 100644
> --- a/include/linux/rpmsg.h
> +++ b/include/linux/rpmsg.h
> @@ -28,11 +28,13 @@ struct rpmsg_endpoint_ops;
>   /**
>    * struct rpmsg_channel_info - channel info representation
>    * @name: name of service
> + * @desc: description of service
>    * @src: local address
>    * @dst: destination address
>    */
>   struct rpmsg_channel_info {
>   	char name[RPMSG_NAME_SIZE];
> +	char desc[RPMSG_NAME_SIZE];
>   	u32 src;
>   	u32 dst;
>   };
> @@ -42,6 +44,7 @@ struct rpmsg_channel_info {
>    * @dev: the device struct
>    * @id: device id (used to match between rpmsg drivers and devices)
>    * @driver_override: driver name to force a match
> + * @desc: description of remote service
>    * @src: local address
>    * @dst: destination address
>    * @ept: the rpmsg endpoint of this channel
> @@ -51,6 +54,7 @@ struct rpmsg_device {
>   	struct device dev;
>   	struct rpmsg_device_id id;
>   	char *driver_override;
> +	char desc[RPMSG_NAME_SIZE];
>   	u32 src;
>   	u32 dst;
>   	struct rpmsg_endpoint *ept;