[REQUEST FOR VOTES] snmpd: Drop support for pass_persist on uClinux

On Sat, Aug 15, 2020 at 09:11:40AM -0700, Bart Van Assche wrote:
> On 2020-08-15 07:14, Magnus Fromreide wrote:
> > This allows vfork to not block the parent until the child has called _exit
> > or exec*, it does not allow the child to block the parent until completion.
> > 
> > Please note that in our case this is arch-specific code for uClinux where
> > the fork() system call doesn't exist so I think we can be assured that vfork
> > will block the parent there.
> 
> On https://www.eetimes.com/how-uclinux-provides-mmu-less-processors-with-an-alternative/#
> I found the following, which confirms the above:
> 
>   uClinux implements vfork() in order to compensate for the lack of fork().
>   When a parent process calls vfork() to create a child, both processes share
>   all their memory space including the stack. vfork() then suspends the
>   parent's execution until the child process either calls exit() or execve().
> 
> > If we had been religous about marking all internal fd's as CLOEXEC then
> > pass_perrsistant could be rewritten using posix_spawn which sounds a lot
> > better but we are sadly lacking in the CLOEXEC department.
> > 
> > To be honest the calls to perror and exit if exec fails is more suspicious as
> > that is explicitly stated to cause undefined behaviour.
> > 
> > With all this I should probably repeat that I am in favour of dropping the
> > pass_persist support for uClinux.
> 
> How about removing the pass_persist for uClinux and restoring it if a
> user asks to restore that support? uClinux was created in 1998, when
> the price difference between microprocessors with or without MMU was
> much larger than today. Today a Raspberry Pi is available for $35. That
> product includes not only a CPU with MMU but also a board and connectors.

That is a more lenient option than just dropping it so I think 'happy with
dropping it' covers this variant. On the other hand I usually am far from
the most conservative one in discussions like  this one.

/MF