Re: Fwd: [PATCH][SMB3 client] fix TCP timers deadlock after rmmod

[Wang Zhaolong]

Hi.

sorry for the late response.

I tested this patch below and it works fine.

Best Regards,
Wang Zhaolong

> I verified the patch below fixed the null-ptr-deref in lockdep by
> preventing cifs from being unloaded while TCP sockets are alive.
>
> I'll post this officialy, and once this is merged and pulled into
> the cifs tree, I'll send a revert of e9f2517a3e18.
>
> ---8<---
> diff --git a/include/net/sock.h b/include/net/sock.h
> index 8daf1b3b12c6..e6515ef9116a 100644
> --- a/include/net/sock.h
> +++ b/include/net/sock.h
> @@ -547,6 +547,10 @@ struct sock {
>   	struct rcu_head		sk_rcu;
>   	netns_tracker		ns_tracker;
>   	struct xarray		sk_user_frags;
> +
> +#if IS_ENABLED(CONFIG_PROVE_LOCKING) && IS_ENABLED(CONFIG_MODULES)
> +	struct module		*sk_owner;
> +#endif
>   };
>   
>   struct sock_bh_locked {
> @@ -1583,6 +1587,16 @@ static inline void sk_mem_uncharge(struct sock *sk, int size)
>   	sk_mem_reclaim(sk);
>   }
>   
> +#if IS_ENABLED(CONFIG_PROVE_LOCKING) && IS_ENABLED(CONFIG_MODULES)
> +static inline void sk_set_owner(struct sock *sk, struct module *owner)
> +{
> +	__module_get(owner);
> +	sk->sk_owner = owner;
> +}
> +#else
> +#define sk_set_owner(sk, owner)
> +#endif
> +
>   /*
>    * Macro so as to not evaluate some arguments when
>    * lockdep is not enabled.
> @@ -1592,6 +1606,7 @@ static inline void sk_mem_uncharge(struct sock *sk, int size)
>    */
>   #define sock_lock_init_class_and_name(sk, sname, skey, name, key)	\
>   do {									\
> +	sk_set_owner(sk, THIS_MODULE);					\
>   	sk->sk_lock.owned = 0;						\
>   	init_waitqueue_head(&sk->sk_lock.wq);				\
>   	spin_lock_init(&(sk)->sk_lock.slock);				\
> diff --git a/net/core/sock.c b/net/core/sock.c
> index 323892066def..b54f12faad1c 100644
> --- a/net/core/sock.c
> +++ b/net/core/sock.c
> @@ -2324,6 +2324,12 @@ static void __sk_destruct(struct rcu_head *head)
>   		__netns_tracker_free(net, &sk->ns_tracker, false);
>   		net_passive_dec(net);
>   	}
> +
> +#if IS_ENABLED(CONFIG_PROVE_LOCKING) && IS_ENABLED(CONFIG_MODULES)
> +	if (sk->sk_owner)
> +		module_put(sk->sk_owner);
> +#endif
> +
>   	sk_prot_free(sk->sk_prot_creator, sk);
>   }
>   
> ---8<---