On Mon, Jan 29, 2024 at 3:24 AM Oleg Nesterov <oleg@xxxxxxxxxx> wrote: > > On 01/27, Oleg Nesterov wrote: > > > > I'll (hopefully) send v2 on top of > > > > pidfd: cleanup the usage of __pidfd_prepare's flags > > pidfd: don't do_notify_pidfd() if !thread_group_empty() > > > > on Monday > > Sorry, I don't have time to finish v2 today, I need to update the comments > and write the changelog. > > But the patch itself is ready, I am sending it for review. > > Tycho, Christian, any comments? Right now, pidfd_send_signal() sends signals to processes, like so: * The syscall currently only signals via PIDTYPE_PID which covers * kill(<positive-pid>, <signal>. It does not signal threads or process * groups. This patch adds PIDFD_THREAD which, potentially confusingly, doesn't change this (AFAICS). So at least that should be documented loudly and clearly, IMO. But I actually just bumped in to this limitation in pidfd_send_signal(), like so: https://github.com/systemd/systemd/issues/31093 Specifically, systemd can't properly emulate Ctrl-C using pidfd_send_signal(). I don't know whether implementing the other signal types belongs as part of this patch, but they're at least thematically related. --Andy
