Hi Peter,
> =============================================
> [ INFO: possible recursive locking detected ]
> 2.6.18-1.2726.fc6 #1
> ---------------------------------------------
> hidd/2271 is trying to acquire lock:
> (sk_lock-AF_BLUETOOTH){--..}, at: [<f8d16241>] bt_accept_dequeue+0x26/0xc6
> [bluetooth]
>
> but task is already holding lock:
> (sk_lock-AF_BLUETOOTH){--..}, at: [<f8bce088>] l2cap_sock_accept+0x41/0x11e [l2cap]
>
> other info that might help us debug this:
> 1 lock held by hidd/2271:
> #0: (sk_lock-AF_BLUETOOTH){--..}, at: [<f8bce088>]
> l2cap_sock_accept+0x41/0x11e [l2cap]
>
> stack backtrace:
> [<c04051ed>] show_trace_log_lvl+0x58/0x16a
> [<c04057fa>] show_trace+0xd/0x10
> [<c0405913>] dump_stack+0x19/0x1b
> [<c043b7dc>] __lock_acquire+0x6ea/0x90d
> [<c043bf70>] lock_acquire+0x4b/0x6b
> [<c05b203b>] lock_sock+0xac/0xbc
> [<f8d16241>] bt_accept_dequeue+0x26/0xc6 [bluetooth]
> [<f8bce129>] l2cap_sock_accept+0xe2/0x11e [l2cap]
> [<c05b142e>] sys_accept+0xd8/0x179
> [<c05b1576>] sys_socketcall+0xa7/0x186
> [<c0403fb7>] syscall_call+0x7/0xb
>
> classical case of nesting; bt_accept_dequeue() locks the children of the object
> locked by l2cap_sock_accept().
>
> Signed-off-by: Peter Zijlstra <[email protected]>
> ---
> include/net/sock.h | 13 ++++++++++++-
> net/bluetooth/l2cap.c | 2 +-
> net/core/sock.c | 6 +++---
> 3 files changed, 16 insertions(+), 5 deletions(-)
>
> Index: linux-2.6/include/net/sock.h
> ===================================================================
> --- linux-2.6.orig/include/net/sock.h
> +++ linux-2.6/include/net/sock.h
> @@ -745,7 +745,18 @@ static inline int sk_stream_wmem_schedul
> */
> #define sock_owned_by_user(sk) ((sk)->sk_lock.owner)
>
> -extern void FASTCALL(lock_sock(struct sock *sk));
> +extern void FASTCALL(_lock_sock(struct sock *sk, int subclass));
> +
> +static inline void lock_sock(struct sock *sk)
> +{
> + _lock_sock(sk, 0);
> +}
> +
> +static inline void lock_sock_nested(struct sock *sk, int subclass)
> +{
> + _lock_sock(sk, subclass);
> +}
> +
> extern void FASTCALL(release_sock(struct sock *sk));
>
> /* BH context may only use the following locking interface. */
> Index: linux-2.6/net/bluetooth/l2cap.c
> ===================================================================
> --- linux-2.6.orig/net/bluetooth/l2cap.c
> +++ linux-2.6/net/bluetooth/l2cap.c
> @@ -770,7 +770,7 @@ static int l2cap_sock_accept(struct sock
> long timeo;
> int err = 0;
>
> - lock_sock(sk);
> + lock_sock_nested(sk, SINGLE_DEPTH_NESTING);
>
> if (sk->sk_state != BT_LISTEN) {
> err = -EBADFD;
> Index: linux-2.6/net/core/sock.c
> ===================================================================
> --- linux-2.6.orig/net/core/sock.c
> +++ linux-2.6/net/core/sock.c
> @@ -1527,7 +1527,7 @@ void sock_init_data(struct socket *sock,
> atomic_set(&sk->sk_refcnt, 1);
> }
>
> -void fastcall lock_sock(struct sock *sk)
> +void fastcall _lock_sock(struct sock *sk, int subclass)
> {
> might_sleep();
> spin_lock_bh(&sk->sk_lock.slock);
> @@ -1538,11 +1538,11 @@ void fastcall lock_sock(struct sock *sk)
> /*
> * The sk_lock has mutex_lock() semantics here:
> */
> - mutex_acquire(&sk->sk_lock.dep_map, 0, 0, _RET_IP_);
> + mutex_acquire(&sk->sk_lock.dep_map, subclass, 0, _RET_IP_);
> local_bh_enable();
> }
>
> -EXPORT_SYMBOL(lock_sock);
> +EXPORT_SYMBOL(_lock_sock);
>
> void fastcall release_sock(struct sock *sk)
> {
for the Bluetooth subsystem part of this patch:
Signed-off-by: Marcel Holtmann <[email protected]>
Regards
Marcel
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