Re: [PATCH v2] prctl: add PR_[GS]ET_KILLABLE

On 07/31, Jürg Billeter wrote:

quoted

Could you explain your use-case? Why a shell wants to use
CLONE_NEWPID?

To guarantee that there won't be any runaway processes, i.e., ensure
that no descendants (background helper daemons or misbehaving
processes) survive when the child process is terminated.

We already have PR_SET_CHILD_SUBREAPER.

Perhaps we can finally add PR_KILL_MY_DESCENDANTS_ON_EXIT? This was already
discussed some time ago, but I can't find the previous discussion... Simple
to implement.

And to prevent
children from killing their ancestors.

OK, this is the only reason for CLONE_NEWPID which I can understand so far.
Not that I understand why this is that useful ;)

quoted

quoted

 * As SIGSTOP is ignored when raised from the SIGNAL_UNKILLABLE process
   itself, it's not possible to implement the stop action in a custom
   SIGTSTP handler.

Yes. So may be we actually want to change __isig() paths to use
SEND_SIG_FORCED (this is not that simple), or perhaps we can change
__send_signal() to not drop SIGSTOP sent to itself, or may be we can even
introduce SIG_DFL_EVEN_IF_INIT, I dunno.

In my opinion, my patch is much simpler and also more general as it

Yes, yes, let me repeat that I am not arguing with your patch, I am just trying
to understand what

quoted

I can't understand this. An application should be changed anyway to do
PR_SET_KILLABLE?

PR_SET_KILLABLE can be called (e.g., by the shell) between clone() and
execve().

OK, this is true.

Oleg.