From: Jarek Poplawski <redacted>
Date: Sun, 10 Feb 2008 14:10:51 +0100

[AX25] af_ax25: remove sock lock in ax25_info_show()
 
This lockdep warning:

quoted

=======================================================
[ INFO: possible circular locking dependency detected ]
2.6.24 #3
-------------------------------------------------------
swapper/0 is trying to acquire lock:
 (ax25_list_lock){-+..}, at: [<f91dd3b1>] ax25_destroy_socket+0x171/0x1f0 [ax25]

but task is already holding lock:
 (slock-AF_AX25){-+..}, at: [<f91dbabc>] ax25_std_heartbeat_expiry+0x1c/0xe0 [ax25]

which lock already depends on the new lock.

...

shows that ax25_list_lock and slock-AF_AX25 are taken in different
order: ax25_info_show() takes slock (bh_lock_sock(ax25->sk)) while
ax25_list_lock is held, so reversely to other functions. To fix this
the sock lock should be moved to ax25_info_start(), and there would
be still problem with breaking ax25_list_lock (it seems this "proper"
order isn't optimal yet). But, since it's only for reading proc info
it seems this is not necessary (e.g.  ax25_send_to_raw() does similar
reading without this lock too).

So, this patch removes sock lock to avoid deadlock possibility; there
is also used sock_i_ino() function, which reads sk_socket under proper
read lock. Additionally printf format of this i_ino is changed to %lu.

Reported-by: Bernard Pidoux F6BVP <redacted>
Signed-off-by: Jarek Poplawski <redacted>

Applied, thanks Jarek.

+			   sock_i_ino(ax25->sk));

Note that this taks the sk callback lock, it should be OK but
let's keep a watch out for any new lockdep warnings this
ends up causing :-)