Jarek Poplawski ecd2ebdea3 [AX25] af_ax25: Possible circular locking. ... Bernard Pidoux F6BVP reported: > When I killall kissattach I can see the following message. > > This happens on kernel 2.6.24-rc5 already patched with the 6 previously > patches I sent recently. > > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.23.9 #1 > ------------------------------------------------------- > kissattach/2906 is trying to acquire lock: > (linkfail_lock){-+..}, at: [<d8bd4603>] ax25_link_failed+0x11/0x39 [ax25] > > but task is already holding lock: > (ax25_list_lock){-+..}, at: [<d8bd7c7c>] ax25_device_event+0x38/0x84 > [ax25] > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: ... lockdep is worried about the different order here: #1 (rose_neigh_list_lock){-+..}: #3 (ax25_list_lock){-+..}: #0 (linkfail_lock){-+..}: #1 (rose_neigh_list_lock){-+..}: #3 (ax25_list_lock){-+..}: #0 (linkfail_lock){-+..}: So, ax25_list_lock could be taken before and after linkfail_lock. I don't know if this three-thread clutch is very probable (or possible at all), but it seems another bug reported by Bernard ("[...] system impossible to reboot with linux-2.6.24-rc5") could have similar source - namely ax25_list_lock held by ax25_kill_by_device() during ax25_disconnect(). It looks like the only place which calls ax25_disconnect() this way, so I guess, it isn't necessary. This patch is breaking the lock for ax25_disconnect(). Reported-and-tested-by: Bernard Pidoux <f6bvp@free.fr> Signed-off-by: Jarek Poplawski <jarkao2@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2008-01-10 21:21:20 -08:00
..
af_ax25.c	[AX25] af_ax25: Possible circular locking.	2008-01-10 21:21:20 -08:00
ax25_addr.c
ax25_dev.c
ax25_ds_in.c	Convert files to UTF-8 and some cleanups	2007-10-19 23:21:04 +02:00
ax25_ds_subr.c	Convert files to UTF-8 and some cleanups	2007-10-19 23:21:04 +02:00
ax25_ds_timer.c
ax25_iface.c	[AX25]: don't free pointers to statically allocated data	2007-08-14 17:24:05 -07:00
ax25_in.c	[NET]: Correct two mistaken skb_reset_mac_header() conversions.	2007-12-20 00:25:54 -08:00
ax25_ip.c	[NET]: Move hardware header operations out of netdevice.	2007-10-10 16:52:52 -07:00
ax25_out.c
ax25_route.c	[NET]: Make all initialized struct seq_operations const.	2007-07-10 23:07:31 -07:00
ax25_std_in.c
ax25_std_subr.c
ax25_std_timer.c
ax25_subr.c	[AX25]: Locking dependencies fix in ax25_disconnect().	2007-12-16 14:02:07 -08:00
ax25_timer.c
ax25_uid.c	[NET]: Make all initialized struct seq_operations const.	2007-07-10 23:07:31 -07:00
Kconfig
Makefile
sysctl_net_ax25.c
TODO