From: Tycho Andersen <tycho@kernel.org>
To: Andrea Parri <parri.andrea@gmail.com>
Cc: Kees Cook <kees@kernel.org>,
Andy Lutomirski <luto@amacapital.net>,
Will Drewry <wad@chromium.org>, Shuah Khan <shuah@kernel.org>,
Christian Brauner <brauner@kernel.org>,
Sargun Dhillon <sargun@sargun.me>, Hui Peng <benquike@gmail.com>,
Bradley Morgan <brads@mainlining.org>,
Cong Wang <cwang@multikernel.io>,
linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
bpf@vger.kernel.org
Subject: Re: [PATCH 1/4] seccomp: wake poll waiters after failed addfd send
Date: Thu, 5 Nov 2026 09:25:17 -0700 [thread overview]
Message-ID: <auysN9YTg8Ih8QLZ@tycho.pizza> (raw)
In-Reply-To: <20261105153735.5368-1-parri.andrea@gmail.com>
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
next prev parent reply other threads:[~2026-11-05 16:25 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-04 10:37 [PATCH 0/4] seccomp: fix user-notification state transitions Andrea Parri
2026-11-04 10:37 ` [PATCH 1/4] seccomp: wake poll waiters after failed addfd send Andrea Parri
2026-11-04 16:19 ` Tycho Andersen
2026-11-05 15:37 ` Andrea Parri
2026-11-05 16:25 ` Tycho Andersen [this message]
2026-11-05 17:35 ` Andrea Parri
2026-11-05 17:42 ` Tycho Andersen
2026-11-05 17:53 ` Andrea Parri
2026-11-04 10:37 ` [PATCH 2/4] seccomp: wake poll waiters after interrupted " Andrea Parri
2026-11-04 10:37 ` [PATCH 3/4] seccomp: add a helper to move a notification to SENT Andrea Parri
2026-11-04 10:37 ` [PATCH 4/4] seccomp: publish user notifications after copying them to userspace Andrea Parri
2026-11-06 11:32 ` [PATCH 0/4] seccomp: fix user-notification state transitions Andrea Parri
2026-11-06 11:36 ` Bradley Morgan
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