once: Fix panic when module unload

DO_ONCE
DEFINE_STATIC_KEY_TRUE(___once_key);
__do_once_done
  once_disable_jump(once_key);
    INIT_WORK(&w->work, once_deferred);
    struct once_work *w;
    w->key = key;
    schedule_work(&w->work);                     module unload
                                                   //*the key is
destroy*
process_one_work
  once_deferred
    BUG_ON(!static_key_enabled(work->key));
       static_key_count((struct static_key *)x)    //*access key, crash*

When module uses DO_ONCE mechanism, it could crash due to the above
concurrency problem, we could reproduce it with link[1].

Fix it by add/put module refcount in the once work process.

[1] https://lore.kernel.org/netdev/[email protected]/

Cc: Hannes Frederic Sowa <[email protected]>
Cc: Daniel Borkmann <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Eric Dumazet <[email protected]>
Reported-by: Minmin chen <[email protected]>
Signed-off-by: Kefeng Wang <[email protected]>
Acked-by: Hannes Frederic Sowa <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

0 files changed, 0 insertions, 0 deletions