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| author |   Jarek Poplawski <jarkao2@gmail.com> | 2007-12-16 14:02:07 -0800 |
|---|---|---|
| committer |   David S. Miller <davem@davemloft.net> | 2007-12-16 14:02:07 -0800 |
| commit | 215f7b08f2a142ec19f4bd3d6de263e68b877955 (patch) | |
| tree | a2f5857336b427d3e47310da2328b4b11fc8ca92 /net/ax25 | |
| parent | [IPV4]: Make tcp_input_metrics() get minimum RTO via tcp_rto_min() (diff) | |
| download | linux-dev-215f7b08f2a142ec19f4bd3d6de263e68b877955.tar.xz linux-dev-215f7b08f2a142ec19f4bd3d6de263e68b877955.zip | |
[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/ax25')
| -rw-r--r-- | net/ax25/ax25_subr.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/net/ax25/ax25_subr.c b/net/ax25/ax25_subr.c index 5fe9b2a6697d..d8f215733175 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(); } } |