From 1f224f1fcc301d291e0ef607b294c5dc3a2b3a5b Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 1 Jul 2011 17:30:00 -0700 Subject: [PATCH] 6pack,mkiss: fix lock inconsistency commit 6e4e2f811bade330126d4029c88c831784a7efd9 upstream. 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: [] 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 Tested-by: Bernard F6BVP Signed-off-by: Arnd Bergmann Acked-by: Ralf Baechle Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/hamradio/6pack.c | 4 ++-- drivers/net/hamradio/mkiss.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/drivers/net/hamradio/6pack.c b/drivers/net/hamradio/6pack.c index 3e5d0b6b6516..0d283781bc5e 100644 --- a/drivers/net/hamradio/6pack.c +++ b/drivers/net/hamradio/6pack.c @@ -692,10 +692,10 @@ 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 4c628393c8b1..bc02968cee16 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; -- 2.39.5