Re: [RFC PATCH v2] can: isotp: add module parameter for maximum pdu size

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 24.03.23 18:29, Marc Kleine-Budde wrote:
> On 22.03.2023 18:59:04, Oliver Hartkopp wrote:
> .> > > I've been thinking about some sendfile() implementation too. But this again
>>>> would bloat the code and would not solve the rx side.
>>>
>>> I'm not talking about sendfile. Have a look at j1939's
>>> j1939_sk_send_loop();
>>>
>>> | https://elixir.bootlin.com/linux/v6.2/source/net/can/j1939/socket.c#L1114
>>>
>>
>> This does not work for isotp like this as you have to handle different block
>> sizes in the flow control message.
> 
> Let this be a task for future us. :)

Let's see if there would be really a use-case that would justify an 
additional complexity.

So far I don't see the need for that.

>>>>> what about: ARRAY_SIZE(so->rx.sbuf)
>>>>>
>>>>
>>>> Looks good. I was just unsure which macro to use ;-)
>>>
>>> You can also use sizeof(so->rx.sbuf).
>>>
>>> ARRAY_SIZE would cause a compile error if you convert so->rx.sbuf to a
>>> pointer to dynamically allocated mem, while sizeof() still compiles.
>>
>> so->rx.sbuf is always a static buffer.
> 
> Yes, in the current code. I was showing the difference between
> ARRAY_SIZE() and sizeof(). ARRAY_SIZE has a bit of type checking, while
> sizeof() doesn't - this becomes important once you change the code.
> 

ACK

>> Only so->rx.buf can point to either so->rx.sbuf or to a dynamically
>> allocated memory.
>>
>> But when sizeof() is always safe it would take this for the v3 patch.
> 
> Use ARRAY_SIZE().

Done. Sent a V3 patch a minute ago.

Many thanks,
Oliver