Re: tcp: Checking a kmemdup() call in tcp_time_wait()

[Eric Dumazet]

On Mon, Oct 14, 2019 at 5:51 AM Markus Elfring <Markus.Elfring@xxxxxx> wrote:
>
> >>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/net/ipv4/tcp_minisocks.c?id=1c0cc5f1ae5ee5a6913704c0d75a6e99604ee30a#n306
> >>>> https://elixir.bootlin.com/linux/v5.4-rc2/source/net/ipv4/tcp_minisocks.c#L306
> â
>
> >> Can an other error reporting approach be nicer here?
> >
> > There is no error reported if kmemdup() has failed.
>
> How do data from the Linux allocation failure report fit to this information?
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=4f5cafb5cb8471e54afdc9054d973535614f7675#n878
>

This is coding style for newly submitted code.

We do not refactor code to the latest coding style, this would cost a lot.

Especially TCP stack that is quite often changed.

>
> > timewait is best effort.
>
> How do you think about to return an error code like â-ENOMEMâ at this place?

tcp_time_wait() is void, the caller won't care. I told you time_wait
is best effort.

What is the problem you want to solve _exactly_ ?

Have you seen a real issue, or should you augment your static analyser
to not complain on :

ptr = kmemdup();
BUG_ON(<any condition>);

(<any condition> being different than (ptr == NULL))

I believe we have enough real bugs to fix.
I would prefer to not spend time arguing for every single BUG() or BUG_ON().

Thank you.