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[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: [<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 <f6bvp@free.fr> Signed-off-by: Jarek Poplawski <jarkao2@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
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1 changed files with 2 additions and 4 deletions
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@ -1928,12 +1928,10 @@ static int ax25_info_show(struct seq_file *seq, void *v)
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ax25->paclen);
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if (ax25->sk != NULL) {
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bh_lock_sock(ax25->sk);
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seq_printf(seq," %d %d %ld\n",
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seq_printf(seq, " %d %d %lu\n",
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atomic_read(&ax25->sk->sk_wmem_alloc),
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atomic_read(&ax25->sk->sk_rmem_alloc),
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ax25->sk->sk_socket != NULL ? SOCK_INODE(ax25->sk->sk_socket)->i_ino : 0L);
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bh_unlock_sock(ax25->sk);
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sock_i_ino(ax25->sk));
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} else {
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seq_puts(seq, " * * *\n");
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}
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