From 1105b5d1d44e6f00e31422dfcb0139bc8ae966a9 Mon Sep 17 00:00:00 2001 From: Jarek Poplawski Date: Mon, 11 Feb 2008 21:24:56 -0800 Subject: [PATCH] [AX25] af_ax25: remove sock lock in ax25_info_show() This lockdep warning: > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.24 #3 > ------------------------------------------------------- > swapper/0 is trying to acquire lock: > (ax25_list_lock){-+..}, at: [] ax25_destroy_socket+0x171/0x1f0 [ax25] > > but task is already holding lock: > (slock-AF_AX25){-+..}, at: [] 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 Signed-off-by: Jarek Poplawski Signed-off-by: David S. Miller --- net/ax25/af_ax25.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/net/ax25/af_ax25.c b/net/ax25/af_ax25.c index 8fc64e3150..5a4337a290 100644 --- a/net/ax25/af_ax25.c +++ b/net/ax25/af_ax25.c @@ -1928,12 +1928,10 @@ static int ax25_info_show(struct seq_file *seq, void *v) ax25->paclen); if (ax25->sk != NULL) { - bh_lock_sock(ax25->sk); - seq_printf(seq," %d %d %ld\n", + seq_printf(seq, " %d %d %lu\n", atomic_read(&ax25->sk->sk_wmem_alloc), atomic_read(&ax25->sk->sk_rmem_alloc), - ax25->sk->sk_socket != NULL ? SOCK_INODE(ax25->sk->sk_socket)->i_ino : 0L); - bh_unlock_sock(ax25->sk); + sock_i_ino(ax25->sk)); } else { seq_puts(seq, " * * *\n"); } -- 2.39.5