Re: [PATCH] pidfd: change pidfd_send_signal() to respect PIDFD_THREAD

From: Oleg Nesterov
Date: Fri Feb 09 2024 - 05:29:52 EST

On 02/08, Oleg Nesterov wrote:
> Is prepare_kill_siginfo() correct when we send a signal to the child
> pid namespace? si_pid = task_tgid_vnr(current) doesn't look right

Yes, but iiuc send_signal_locked() should fixup si_pid/si_uid, so it
is not buggy.

> And why do we need it at all? Can't sys_kill() and pidfd_send_signal()
> just use SEND_SIG_NOINFO?

Probably yes. And even do_tkill() can use SEND_SIG_NOINFO if we change
__send_signal_locked() to check the type before ".si_code = SI_USER".
but then TP_STORE_SIGINFO() needs some changes...

I'll try to do this later, I do not want to mix this change with the