Re: [PATCH v2] rpmsg: core: Add wildcard match for name service

From: Suman Anna
Date: Thu Mar 26 2020 - 16:42:47 EST


On 3/26/20 3:21 PM, Mathieu Poirier wrote:
> On Thu, 26 Mar 2020 at 09:06, Suman Anna <s-anna@xxxxxx> wrote:
>>
>> Hi Mathieu,
>>
>> On 3/10/20 10:50 AM, Mathieu Poirier wrote:
>>> Adding the capability to supplement the base definition published
>>> by an rpmsg_driver with a postfix description so that it is possible
>>> for several entity to use the same service.
>>>
>>> Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
>>> Acked-by: Arnaud Pouliquen <arnaud.pouliquen@xxxxxx>
>>
>> So, the concern I have here is that we are retrofitting this into the
>> existing 32-byte name field, and the question is if it is going to be
>> enough in general. That's the reason I went with the additional 32-byte
>> field with the "rpmsg: add a description field" patch.
>>
>
> That's a valid concern.
>
> Did you consider increasing the size of RPMSG_NAME_SIZE to 64? Have
> you found cases where that wouldn't work? I did a survey of all the
> places the #define is used and all destination buffers are also using
> the same #define in their definition. It would also be backward
> compatible with firmware implementations that use 32 byte.

You can't directly bump the size without breaking the compatibility on
the existing rpmsg_ns_msg in firmwares right? All the Linux-side drivers
will be ok since they use the same macro but rpmsg_ns_msg has presence
on both kernel and firmware-sides.

regards
Suman

>
> Thanks,
> Mathieu
>
>> regards
>> Suman
>>
>>> ---
>>> Changes for V2:
>>> - Added Arnaud's Acked-by.
>>> - Rebased to latest rproc-next.
>>>
>>> drivers/rpmsg/rpmsg_core.c | 20 +++++++++++++++++++-
>>> 1 file changed, 19 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/rpmsg/rpmsg_core.c b/drivers/rpmsg/rpmsg_core.c
>>> index e330ec4dfc33..bfd25978fa35 100644
>>> --- a/drivers/rpmsg/rpmsg_core.c
>>> +++ b/drivers/rpmsg/rpmsg_core.c
>>> @@ -399,7 +399,25 @@ ATTRIBUTE_GROUPS(rpmsg_dev);
>>> static inline int rpmsg_id_match(const struct rpmsg_device *rpdev,
>>> const struct rpmsg_device_id *id)
>>> {
>>> - return strncmp(id->name, rpdev->id.name, RPMSG_NAME_SIZE) == 0;
>>> + size_t len = min_t(size_t, strlen(id->name), RPMSG_NAME_SIZE);
>>> +
>>> + /*
>>> + * Allow for wildcard matches. For example if rpmsg_driver::id_table
>>> + * is:
>>> + *
>>> + * static struct rpmsg_device_id rpmsg_driver_sample_id_table[] = {
>>> + * { .name = "rpmsg-client-sample" },
>>> + * { },
>>> + * }
>>> + *
>>> + * Then it is possible to support "rpmsg-client-sample*", i.e:
>>> + * rpmsg-client-sample
>>> + * rpmsg-client-sample_instance0
>>> + * rpmsg-client-sample_instance1
>>> + * ...
>>> + * rpmsg-client-sample_instanceX
>>> + */
>>> + return strncmp(id->name, rpdev->id.name, len) == 0;
>>> }
>>>
>>> /* match rpmsg channel and rpmsg driver */
>>>
>>