linux-stable/drivers/s390
Sebastian Ott 0eb69a0c58 s390/airq: silence lockdep warning
airq_iv_(alloc|free) is called by some users with interrupts enabled
and by some with interrupts disabled which leads to the following
lockdep warning:

[ INFO: possible irq lock inversion dependency detected ]
3.14.0-15249-gbf29b7b-dirty #25 Not tainted
---------------------------------------------------------
insmod/2108 just changed the state of lock:
 (&(&iv->lock)->rlock){+.....}, at: [<000000000046ee3e>] airq_iv_alloc+0x62/0x228
but this lock was taken by another, HARDIRQ-READ-safe lock in the past:
 (&info->lock){.-.-..}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
 Possible interrupt unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&(&iv->lock)->rlock);
                               local_irq_disable();
                               lock(&info->lock);
                               lock(&(&iv->lock)->rlock);
  <Interrupt>
    lock(&info->lock);

 *** DEADLOCK ***

Although this is a false alarm (since each airq user consistently
calls these functions from the same context) fix this by ensuring
that interrupts are disabled when the airq lock is held.

Reported-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
2014-06-10 10:48:30 +02:00
..
block Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2014-04-08 12:02:28 -07:00
char s390/watchdog: use watchdog API 2014-06-10 10:48:29 +02:00
cio s390/airq: silence lockdep warning 2014-06-10 10:48:30 +02:00
crypto s390/ap_bus: Make modules parameters visible in sysfs 2014-06-10 10:48:27 +02:00
kvm Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux 2014-04-08 12:02:28 -07:00
net s390/cio: fix multiple structure definitions 2014-05-20 08:58:53 +02:00
scsi Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial 2013-11-15 16:47:22 -08:00
Makefile