Messages in this thread Patch in this message | | | Date | Fri, 08 Jul 2011 15:50:08 -0700 | From | Greg KH <> | Subject | [19/35] 6pack,mkiss: fix lock inconsistency |
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2.6.32-longterm review patch. If anyone has any objections, please let us know.
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From: Arnd Bergmann <arnd@arndb.de>
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: [<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> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- drivers/net/hamradio/6pack.c | 4 ++-- drivers/net/hamradio/mkiss.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-)
--- a/drivers/net/hamradio/6pack.c +++ b/drivers/net/hamradio/6pack.c @@ -690,10 +690,10 @@ static void sixpack_close(struct tty_str { 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; --- a/drivers/net/hamradio/mkiss.c +++ b/drivers/net/hamradio/mkiss.c @@ -811,10 +811,10 @@ static void mkiss_close(struct tty_struc { 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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