Re: [PATCH 1/4] seccomp: wake poll waiters after failed addfd send

[Tycho Andersen]

On Thu, Nov 05, 2026 at 04:37:34PM +0100, Andrea Parri wrote:
> On Wed, Nov 04, 2026 at 09:19:10AM -0700, Tycho Andersen wrote:
> > Hm, don't we return success or failure from
> > ioctl(SECCOMP_IOCTL_NOTIF_ADDFD) via kaddfd.ret in
> > seccomp_notify_addfd()?
> >
> > I don't really understand why this is necessary unless you're ignoring
> > the return value from that call.
> 
> Right, the issuing thread gets the error and can recover directly.  The
> edge-triggered example demonstrates the missing wakeup, but does not
> establish that a supervisor needs it to recover.

...

> I don't know of a supervisor that waits for EPOLLOUT from a thread
> other than the one replying ... not to fix a reported hang.

Seems like a solution in search of a problem to me.

Is there a sane action a supervisor can take on failure here besides
killing the thread that made the syscall? If so, perhaps it's
worthwhile. Or maybe it's worth it "for completeness" and I'm just
being grumpy :)

Tycho