Re: [PATCH] candump: add option to ignore ENOBUFS

[Oliver Hartkopp <socketcan@hartkopp.net>]

On 13.01.2014 11:00, Yegor Yefremov wrote:
> On Fri, Jan 10, 2014 at 11:02 PM, Oliver Hartkopp
> <socketcan@hartkopp.net> wrote:
>> Hi Yegor,
>>
>> the question about a blocking write was still not addressed :-(
> 
> Is this something to change in the generic networking stack or just
> SocketCAN core?

AFAICR it has something to do with socket buffer sizes and the poll function
which has to be implemented in CAN_RAW.

> I'm trying to add network functionality to slcanpty,c Reading from
> socket or pty doesn't make a big difference. But as soon as you try to
> send a lot of frames, you get ENOBUFS at once. I'm trying to
> understand, what is the best way to handle this situation. In cangen
> the situation is rather trivial, as one just sends. In slcanpty it
> should support simultaneous read/write, so I'll have to store unsent
> CAN frames somewhere, return to select handling and handle read stuff,
> before retrying send.

When you use a blocking write this may also slow down the original ASCII
source. You should probably think of two separate threads for rx/tx.

Regards,
Oliver