netdevsim: psp: serialize calls to nsim_psp_uninit()

The debugfs write handler, nsim_psp_rereg_write(), can race against
nsim_destroy() and against itself, causing nsim_psp_uninit() to run
more than once concurrently. Two complementary changes serialize all
callers:

1. Delete the psp_rereg debugfs file from nsim_psp_uninit() before
   doing the actual teardown. debugfs_remove() drains any in-flight
   writers and prevents new ones from starting.

2. Add a mutex around the body of nsim_psp_rereg_write() so that two
   concurrent userspace writers cannot both enter the teardown path
   at once.

The teardown work itself is moved into a new __nsim_psp_uninit() that
the rereg handler calls under the mutex, while the public
nsim_psp_uninit() wraps it with the debugfs_remove()/mutex_destroy()
pair so nsim_destroy() doesn't have to know about the psp internals.

Fixes: f857478d6206 ("netdevsim: a basic test PSP implementation")
Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260505-psd-rcu-v1-2-a8f69ec1ab96@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions