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Subject: Re: [PATCH v2 4/9] rpmsg: Move rpmsg_hr and rpmsg_ns_msg to header
 file
To:     Mathieu Poirier <mathieu.poirier@linaro.org>
CC:     "ohad@wizery.com" <ohad@wizery.com>,
        "bjorn.andersson@linaro.org" <bjorn.andersson@linaro.org>,
        "guennadi.liakhovetski@linux.intel.com" 
        <guennadi.liakhovetski@linux.intel.com>,
        "linux-remoteproc@vger.kernel.org" <linux-remoteproc@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20201013232519.1367542-1-mathieu.poirier@linaro.org>
 <20201013232519.1367542-5-mathieu.poirier@linaro.org>
 <61c25983-a339-e5de-eaf7-d608a9b9771b@st.com>
 <20201015201926.GF1450102@xps15>
From:   Arnaud POULIQUEN <arnaud.pouliquen@st.com>
Message-ID: <cce4b049-a210-7c1b-a842-5f238ef89fc0@st.com>
Date:   Fri, 16 Oct 2020 11:45:11 +0200
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On 10/15/20 10:19 PM, Mathieu Poirier wrote:
> On Thu, Oct 15, 2020 at 10:33:25AM +0200, Arnaud POULIQUEN wrote:
>> Hi Mathieu,
>>
>> On 10/14/20 1:25 AM, Mathieu Poirier wrote:
>>> Move structures rpmsg_hdr and rpmsg_ns_msg to their own header file
>>> so that they can be used by other entities.
>>>
>>> Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
>>> ---
>>>  drivers/rpmsg/virtio_rpmsg_bus.c | 58 ++----------------------------
>>>  include/linux/rpmsg_ns.h         | 62 ++++++++++++++++++++++++++++++++
>>>  include/uapi/linux/rpmsg.h       |  3 ++
>>>  3 files changed, 67 insertions(+), 56 deletions(-)
>>>  create mode 100644 include/linux/rpmsg_ns.h
>>>
>>> diff --git a/drivers/rpmsg/virtio_rpmsg_bus.c b/drivers/rpmsg/virtio_rpmsg_bus.c
>>> index 793fe924671f..85f2acc4ed9f 100644
>>> --- a/drivers/rpmsg/virtio_rpmsg_bus.c
>>> +++ b/drivers/rpmsg/virtio_rpmsg_bus.c
>>> @@ -19,7 +19,7 @@
>>>  #include <linux/mutex.h>
>>>  #include <linux/of_device.h>
>>>  #include <linux/rpmsg.h>
>>> -#include <linux/rpmsg_byteorder.h>
>>> +#include <linux/rpmsg_ns.h>
>>>  #include <linux/scatterlist.h>
>>>  #include <linux/slab.h>
>>>  #include <linux/sched.h>
>>> @@ -27,6 +27,7 @@
>>>  #include <linux/virtio_ids.h>
>>>  #include <linux/virtio_config.h>
>>>  #include <linux/wait.h>
>>> +#include <uapi/linux/rpmsg.h>
>>>  
>>>  #include "rpmsg_internal.h"
>>>  
>>> @@ -70,58 +71,6 @@ struct virtproc_info {
>>>  	struct rpmsg_endpoint *ns_ept;
>>>  };
>>>  
>>> -/* The feature bitmap for virtio rpmsg */
>>> -#define VIRTIO_RPMSG_F_NS	0 /* RP supports name service notifications */
>>> -
>>> -/**
>>> - * struct rpmsg_hdr - common header for all rpmsg messages
>>> - * @src: source address
>>> - * @dst: destination address
>>> - * @reserved: reserved for future use
>>> - * @len: length of payload (in bytes)
>>> - * @flags: message flags
>>> - * @data: @len bytes of message payload data
>>> - *
>>> - * Every message sent(/received) on the rpmsg bus begins with this header.
>>> - */
>>> -struct rpmsg_hdr {
>>> -	__rpmsg32 src;
>>> -	__rpmsg32 dst;
>>> -	__rpmsg32 reserved;
>>> -	__rpmsg16 len;
>>> -	__rpmsg16 flags;
>>> -	u8 data[];
>>> -} __packed;
>>> -
>>> -/**
>>> - * struct rpmsg_ns_msg - dynamic name service announcement message
>>> - * @name: name of remote service that is published
>>> - * @addr: address of remote service that is published
>>> - * @flags: indicates whether service is created or destroyed
>>> - *
>>> - * This message is sent across to publish a new service, or announce
>>> - * about its removal. When we receive these messages, an appropriate
>>> - * rpmsg channel (i.e device) is created/destroyed. In turn, the ->probe()
>>> - * or ->remove() handler of the appropriate rpmsg driver will be invoked
>>> - * (if/as-soon-as one is registered).
>>> - */
>>> -struct rpmsg_ns_msg {
>>> -	char name[RPMSG_NAME_SIZE];
>>> -	__rpmsg32 addr;
>>> -	__rpmsg32 flags;
>>> -} __packed;
>>> -
>>> -/**
>>> - * enum rpmsg_ns_flags - dynamic name service announcement flags
>>> - *
>>> - * @RPMSG_NS_CREATE: a new remote service was just created
>>> - * @RPMSG_NS_DESTROY: a known remote service was just destroyed
>>> - */
>>> -enum rpmsg_ns_flags {
>>> -	RPMSG_NS_CREATE		= 0,
>>> -	RPMSG_NS_DESTROY	= 1,
>>> -};
>>> -
>>>  /**
>>>   * @vrp: the remote processor this channel belongs to
>>>   */
>>> @@ -162,9 +111,6 @@ struct virtio_rpmsg_channel {
>>>   */
>>>  #define RPMSG_RESERVED_ADDRESSES	(1024)
>>>  
>>> -/* Address 53 is reserved for advertising remote services */
>>> -#define RPMSG_NS_ADDR			(53)
>>> -
>>>  static void virtio_rpmsg_destroy_ept(struct rpmsg_endpoint *ept);
>>>  static int virtio_rpmsg_send(struct rpmsg_endpoint *ept, void *data, int len);
>>>  static int virtio_rpmsg_sendto(struct rpmsg_endpoint *ept, void *data, int len,
>>> diff --git a/include/linux/rpmsg_ns.h b/include/linux/rpmsg_ns.h
>>> new file mode 100644
>>> index 000000000000..3d836b8580b2
>>> --- /dev/null
>>> +++ b/include/linux/rpmsg_ns.h
>>> @@ -0,0 +1,62 @@
>>> +/* SPDX-License-Identifier: GPL-2.0 */
>>> +
>>> +#ifndef _LINUX_RPMSG_NS_H
>>> +#define _LINUX_RPMSG_NS_H
>>> +
>>> +#include <linux/mod_devicetable.h>
>>> +#include <linux/types.h>
>>> +#include <linux/rpmsg_byteorder.h>
>>> +
>>> +/**
>>> + * struct rpmsg_hdr - common header for all rpmsg messages
>>> + * @src: source address
>>> + * @dst: destination address
>>> + * @reserved: reserved for future use
>>> + * @len: length of payload (in bytes)
>>> + * @flags: message flags
>>> + * @data: @len bytes of message payload data
>>> + *
>>> + * Every message sent(/received) on the rpmsg bus begins with this header.
>>> + */
>>> +struct rpmsg_hdr {
>>> +	__rpmsg32 src;
>>> +	__rpmsg32 dst;
>>> +	__rpmsg32 reserved;
>>> +	__rpmsg16 len;
>>> +	__rpmsg16 flags;
>>> +	u8 data[];
>>> +} __packed;
>>
>> This structure is not related to the rpmsg ns service but to the rpmsg bus.
>> If this structure has to be exposed to rpmsg client should be in rpmsg.h, but 
>> Is there a need to expose it for now?
>> I suppose that it is for vhost...As the need will depends on the implementation, 
>> I would suggest leaving it internally and expose only if needed, in the
>> related series.
>>
> 
> I also thought about moving rpmsg_hdr to rpmsg.h but decided against because in
> most cases using the name space service usually means that a message header will
> be required.  I also thought it would be easier to use, i.e include one header
> rather than two.  That too is a little thin because anyone using a name service
> will also need to get access to rpmsg_device, which is in rpmsg.h.
> 
> I'm definitely not strongly opinionated on where it should go, or I can leave it
> in virtio_rpmsg_bus.c too... 

The rpmsg_ns service does not use this structure. So seems to me not at the good place

The virtio_rpmsg.c does, and a vhost_rpmsg.c should do it as well.
I would be in favor of moving it to rpmsg_internal.h to expose it to
the rpmg_buses (e.g. rpmsg_vhost) as a generic message header.
Leaving it in virtio_rpmsg_bus.c also seems also a good alternative.

>  
>>> +
>>> +/**
>>> + * struct rpmsg_ns_msg - dynamic name service announcement message
>>> + * @name: name of remote service that is published
>>> + * @addr: address of remote service that is published
>>> + * @flags: indicates whether service is created or destroyed
>>> + *
>>> + * This message is sent across to publish a new service, or announce
>>> + * about its removal. When we receive these messages, an appropriate
>>> + * rpmsg channel (i.e device) is created/destroyed. In turn, the ->probe()
>>> + * or ->remove() handler of the appropriate rpmsg driver will be invoked
>>> + * (if/as-soon-as one is registered).
>>> + */
>>> +struct rpmsg_ns_msg {
>>> +	char name[RPMSG_NAME_SIZE];
>>> +	__rpmsg32 addr;
>>> +	__rpmsg32 flags;
>>> +} __packed;
>>> +
>>> +/**
>>> + * enum rpmsg_ns_flags - dynamic name service announcement flags
>>> + *
>>> + * @RPMSG_NS_CREATE: a new remote service was just created
>>> + * @RPMSG_NS_DESTROY: a known remote service was just destroyed
>>> + */
>>> +enum rpmsg_ns_flags {
>>> +	RPMSG_NS_CREATE		= 0,
>>> +	RPMSG_NS_DESTROY	= 1,
>>> +};
>>> +
>>> +/* Address 53 is reserved for advertising remote services */
>>> +#define RPMSG_NS_ADDR			(53)
>>
>> What about my proposal [1] to put this in rpmsg.h, to create a list of
>> reserved Address
> 
> That too is a grey area... Moving RPMSG_NS_ADDR to rpmsg.h means we have a name
> service #define in rpmsg.h.  I think that one should stay in rpmsg_ns.h. 

That seems reasonable, very simple to change this in future if needed.

Regards
Arnaud

> 
>>
>> [1] https://lkml.org/lkml/2020/7/31/442
>>
>>> +
>>> +#endif
>>> diff --git a/include/uapi/linux/rpmsg.h b/include/uapi/linux/rpmsg.h
>>> index e14c6dab4223..d669c04ef289 100644
>>> --- a/include/uapi/linux/rpmsg.h
>>> +++ b/include/uapi/linux/rpmsg.h
>>> @@ -24,4 +24,7 @@ struct rpmsg_endpoint_info {
>>>  #define RPMSG_CREATE_EPT_IOCTL	_IOW(0xb5, 0x1, struct rpmsg_endpoint_info)
>>>  #define RPMSG_DESTROY_EPT_IOCTL	_IO(0xb5, 0x2)
>>>  
>>> +/* The feature bitmap for virtio rpmsg */
>>> +#define VIRTIO_RPMSG_F_NS	0 /* RP supports name service notifications */
>>> +
>>
>> Same suggestion here,i would drop this from this series
> 
> Will do.
> 
> Thanks for the feedback,
> Mathieu
> 
>>
>> Thanks,
>> Arnaud
>>
>>>  #endif
>>>