tty: isicom: fix deadlock on shutdown
authorAlan Cox <alan@linux.intel.com>
Mon, 30 Nov 2009 13:17:46 +0000 (13:17 +0000)
committerGreg Kroah-Hartman <gregkh@suse.de>
Fri, 11 Dec 2009 23:18:07 +0000 (15:18 -0800)
commit2493c0c166565e36831196446af594eb07892daf
tree0175b121f39076dbd858fd7e475885e9d804a5f4
parent07f86c03fec711692121bf7f5316e0b3426acc05
tty: isicom: fix deadlock on shutdown

Alexander Strakh <strakh@ispras.ru> reported

KERNEL_VERSION: 2.6.31
DESCRIBE:
Driver drivers/char/isicom.c might sleep in atomic  context, because it
calls
tty_port_xmit_buf under spin_lock.

./drivers/char/isicom.c:
1307 static void isicom_hangup(struct tty_struct *tty)
1308 {
...
1315         spin_lock_irqsave(&port->card->card_lock, flags);
1316         isicom_shutdown_port(port);
...

Path to might_sleep macro from isicom_hangup:
1. isicom_hangup calls spin_lock_irqsave (drivers/char/isicom.c:1315) and
then
calls isicom_shutdown_port.
2. isiscom_shutdown_port calls tty_port_free_xmit_buf at
drivers/char/isicom.c:906
3. tty_port_free_xmit_buf calls mutex_lock at drivers/char/tty_port:48

Found by Linux Driver Verification Project.

Reported-by: Alexander Strakh <strakh@ispras.ru>
Signed-off-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
drivers/char/isicom.c