Merge branch 'netdevsim-psp-fix-init-and-uninit-bugs'

Daniel Zahka says:

====================
netdevsim: psp: fix init and uninit bugs

This series has three fixes. The first is a straightforward NULL
pointer dereference that is reachable by creating and destroying some
vfs on a kernel with INET_PSP enabled.

The last two patches deal with nsim_psp_rereg_write(), which is a
debugfs handler that reregisters netdevsim's psp_dev without
aquiescing and disabling tx/rx processing. This was added to enable
some tests in psp.py where a psp device is unregistered while it still
referenced by tcp socket state.

There are two issues with this code:
1. Calls to nsim_psp_uninit() are not properly serialized
2. netdevsim's psp_dev refcount can be released while nsim_do_psp() is
   reading from it.
====================

Link: https://patch.msgid.link/20260505-psd-rcu-v1-0-a8f69ec1ab96@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>