Re: [PATCH v3 9/9] h264: register shutdown notifiers, stop pipeline in destroy_encoder_context

["Daniel P. Berrangé" <berrange@redhat.com>]

On Tue, Apr 22, 2025 at 08:35:52AM +0200, Dietmar Maurer wrote:
> > On Fri, Apr 18, 2025 at 3:30 PM Dietmar Maurer <dietmar@proxmox.com> wrote:
> > >
> > > Some encoders can hang indefinetly (i.e. nvh264enc) if
> > 
> > indefinitely
> > 
> > > the pipeline is not stopped before it is destroyed
> > > (Observed on Debian bookworm).
> > 
> > but why do you need the extra shutdown notifier?
> 
> Because Qemu does not close open VNC connections on shutdown.
> and if the VNC connection is open, the h264 pipeline is still active,
> which cause the Qemu process to hang (CTRL-C does not stop it, only kill -9)

This is surely liable to be a race condition that causes crashes. The still
open VNC connection may still reference the encoder that you're destroying,
allowing the VNC worker thread to potentially access free'd memory.

With regards,
Daniel
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