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authorJarek Poplawski <jarkao2@gmail.com>2007-12-16 14:02:07 -0800
committerDavid S. Miller <davem@davemloft.net>2007-12-16 14:02:07 -0800
commit215f7b08f2a142ec19f4bd3d6de263e68b877955 (patch)
treea2f5857336b427d3e47310da2328b4b11fc8ca92 /net
parent488faa2ae32c2f8b1ffda5c7fae5eb7c979acc15 (diff)
[AX25]: Locking dependencies fix in ax25_disconnect().
Bernard Pidoux reported these lockdep warnings: [ INFO: possible irq lock inversion dependency detected ] 2.6.23.1 #1 --------------------------------------------------------- fpac/4933 just changed the state of lock: (slock-AF_AX25){--..}, at: [<d8be3312>] ax25_disconnect+0x46/0xaf [ax25] but this lock was taken by another, soft-irq-safe lock in the past: (ax25_list_lock){-+..} and interrupts could create inverse lock ordering between them. [...] [ INFO: inconsistent lock state ] 2.6.23.1 #1 --------------------------------- inconsistent {in-softirq-W} -> {softirq-on-W} usage. ax25_call/4005 [HC0[0]:SC0[0]:HE1:SE1] takes: (slock-AF_AX25){-+..}, at: [<d8b79312>] ax25_disconnect+0x46/0xaf [ax25] [...] This means slock-AF_AX25 could be taken both from softirq and process context with softirqs enabled, so it's endangered itself, but also makes ax25_list_lock vulnerable. It was not 100% verified if the real lockup can happen, but this fix isn't very costly and looks safe anyway. (It was tested by Bernard with 2.6.23.9 and 2.6.24-rc5 kernels.) Reported_by: Bernard Pidoux <pidoux@ccr.jussieu.fr> Tested_by: Bernard Pidoux <pidoux@ccr.jussieu.fr> Signed-off-by: Jarek Poplawski <jarkao2@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net')
-rw-r--r--net/ax25/ax25_subr.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/net/ax25/ax25_subr.c b/net/ax25/ax25_subr.c
index 5fe9b2a6697..d8f21573317 100644
--- a/net/ax25/ax25_subr.c
+++ b/net/ax25/ax25_subr.c
@@ -279,6 +279,7 @@ void ax25_disconnect(ax25_cb *ax25, int reason)
ax25_link_failed(ax25, reason);
if (ax25->sk != NULL) {
+ local_bh_disable();
bh_lock_sock(ax25->sk);
ax25->sk->sk_state = TCP_CLOSE;
ax25->sk->sk_err = reason;
@@ -288,5 +289,6 @@ void ax25_disconnect(ax25_cb *ax25, int reason)
sock_set_flag(ax25->sk, SOCK_DEAD);
}
bh_unlock_sock(ax25->sk);
+ local_bh_enable();
}
}