Re: [PATCH net-next 04/12] selftests/vsock: avoid multi-VM pidfile collisions with QEMU

[Bobby Eshleman <bobbyeshleman@gmail.com>]

On Mon, Oct 27, 2025 at 04:57:29PM +0000, Simon Horman wrote:
> On Wed, Oct 22, 2025 at 06:00:08PM -0700, Bobby Eshleman wrote:
> > From: Bobby Eshleman <bobbyeshleman@meta.com>
> > 
> > Change QEMU to use generated pidfile names instead of just a single
> > globally-defined pidfile. This allows multiple QEMU instances to
> > co-exist with different pidfiles. This is required for future tests that
> > use multiple VMs to check for CID collissions.
> > 
> > Additionally, this also places the burden of killing the QEMU process
> > and cleaning up the pidfile on the caller of vm_start(). To help with
> > this, a function terminate_pidfiles() is introduced that callers use to
> > perform the cleanup. The terminate_pidfiles() function supports multiple
> > pidfile removals because future patches will need to process two
> > pidfiles at a time.
> 
> It seems that this will no longer cleanup, via a trap, if
> there is an early exit. Is that intentional?
> 

Yes, intentional. We're trusting the vm_start() caller to do any cleanup
now. The assumption being that with no "set -e", vm_start() should be
able to return to the caller.

If that seems too bold, we could add some function like create_pidfile()
that generates the pidfiles and registers them into an array that is
cleaned up via trap.

> This patch also changes the handling of QEMU_OPTS. I think
> that should be mentioned in the commit message too.
> 

Sounds good.

Best,
Bobby