Messages in this thread Patch in this message | | | From | Arnd Bergmann <> | Subject | [PATCH] 6pack,mkiss: fix lock inconsistency | Date | Fri, 1 Jul 2011 23:28:46 +0200 |
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Lockdep found a locking inconsistency in the mkiss_close function:
> kernel: [ INFO: inconsistent lock state ] > kernel: 2.6.39.1 #3 > kernel: --------------------------------- > kernel: inconsistent {IN-SOFTIRQ-R} -> {SOFTIRQ-ON-W} usage. > kernel: ax25ipd/2813 [HC0[0]:SC0[0]:HE1:SE1] takes: > kernel: (disc_data_lock){+++?.-}, at: [<ffffffffa018552b>] mkiss_close+0x1b/0x90 [mkiss] > kernel: {IN-SOFTIRQ-R} state was registered at:
The message hints that disc_data_lock is aquired with softirqs disabled, but does not itself disable softirqs, which can in rare circumstances lead to a deadlock. The same problem is present in the 6pack driver, this patch fixes both by using write_lock_bh instead of write_lock.
Reported-by: Bernard F6BVP <f6bvp@free.fr> Tested-by: Bernard F6BVP <f6bvp@free.fr> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Acked-by: Ralf Baechle<ralf@linux-mips.org> Cc: stable@kernel.org --- On Friday 01 July 2011 15:00:35 Bernard F6BVP wrote: > > Now, who is going to commit this mkiss patch and the equivalent one for > sixpack.c ?
Here's a formal patch with all the right tags, I assume that David Miller will apply that to the netdev tree.
diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c index 9624cbf..fea7cb4 100644 --- a/drivers/net/hamradio/6pack.c +++ b/drivers/net/hamradio/6pack.c @@ -694,10 +694,10 @@ static void sixpack_close(struct tty_struct *tty) { struct sixpack *sp; - write_lock(&disc_data_lock); + write_lock_bh(&disc_data_lock); sp = tty->disc_data; tty->disc_data = NULL; - write_unlock(&disc_data_lock); + write_unlock_bh(&disc_data_lock); if (!sp) return; diff --git a/drivers/net/hamradio/mkiss.c b/drivers/net/hamradio/mkiss.c index 9f84c83..324f7bf 100644 --- a/drivers/net/hamradio/mkiss.c +++ b/drivers/net/hamradio/mkiss.c @@ -813,10 +813,10 @@ static void mkiss_close(struct tty_struct *tty) { struct mkiss *ax; - write_lock(&disc_data_lock); + write_lock_bh(&disc_data_lock); ax = tty->disc_data; tty->disc_data = NULL; - write_unlock(&disc_data_lock); + write_unlock_bh(&disc_data_lock); if (!ax) return;
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