bug#6074: accept-process-output on listening sockets cause non-interruptible infloop

[Lars Ingebrigtsen]

Pip Cet <pipcet@gmail.com> writes:

> Why would we try again after receiving EINVAL? I believe the right
> behavior is to return immediately in this case, just as we do for EIO.
>
> However, we should probably call rarely_quit inside the loop, anyway,
> to catch the case of a kernel bug keeping us busy with EINTRs. How's
> this?

[...]

>           {
> +           unsigned int count = 0;
>             XSETPROCESS (proc, wait_proc);
>  
>             while (true)
>               {
>                 int nread = read_process_output (proc, wait_proc->infd);
> +               rarely_quit (++count);
>                 if (nread < 0)
>                   {
> -                   if (errno == EIO || would_block (errno))
> +                   if (errno != EINTR)
>                       break;
>                   }
>                 else

There was no followup on this patch at the time (except Richard chiding
you for using forbidden terminology), but I tried the patch now, and it
seems to fix the issue, so I've applied it to the trunk now.

-- 
(domestic pets only, the antidote for overdose, milk.)
   bloggy blog: http://lars.ingebrigtsen.no