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linux/drivers/s390/cio
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Sebastian Ott dbe33fc9ad s390/cio: silence lockdep warning 
On systems where a ccw based console device is used a lockdep false alarm
could be triggered when a device driver calls printk while holding a
subchannels lock (e.g. in it's irq handler). Since this is valid behavior
fix this by introducing a separate lock class for the console subchannels
lock.

The lockdep warning was revealed by "printk: enable interrupts before calling
console_trylock_for_printk()" which changed console_unlock() to be called with
lockdep enabled.

[ INFO: possible recursive locking detected ]
3.15.0-rc5-next-20140520 #1 Not tainted
---------------------------------------------
ccwgroup/2239 is trying to acquire lock:
(&(sch->lock)->rlock){-.-...}, at: [<0000000000642a52>] raw3215_write+0x52/0x200

but task is already holding lock:
(&(sch->lock)->rlock){-.-...}, at: [<00000000005fd160>] do_cio_interrupt+0x60/0x108

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

CPU0
----
lock(&(sch->lock)->rlock);
lock(&(sch->lock)->rlock);

*** DEADLOCK ***

May be due to missing lock nesting notation

8 locks held by ccwgroup/2239:

stack backtrace:
CPU: 3 PID: 2239 Comm: ccwgroup Not tainted 3.15.0-rc5-next-20140520 #1
0000000036fab518 0000000036fab528 0000000000000002 0000000000000000
0000000036fab5b8 0000000036fab530 0000000036fab530 00000000001116e8
0000000000000000 0000000000986ec4 00000000009701b6 000000000000000b
0000000036fab578 0000000036fab518 0000000000000000 0000000000000000
0000000000000000 00000000001116e8 0000000036fab518 0000000036fab578
Call Trace:
([<0000000000111626>] show_trace+0x14e/0x158)
[<000000000011169a>] show_stack+0x6a/0xe8
[<00000000007c6e72>] dump_stack+0x82/0xb0
[<00000000001a95f2>] validate_chain.isra.37+0xa4a/0xbb0
[<00000000001acaca>] __lock_acquire+0x4da/0xcd0
[<00000000001ada1a>] lock_acquire+0xba/0x218
[<00000000007cd634>] _raw_spin_lock_irqsave+0x6c/0xb8
[<0000000000642a52>] raw3215_write+0x52/0x200
[<0000000000643d16>] con3215_write+0x76/0xf8
[<00000000001bd87a>] call_console_drivers.constprop.25+0xfa/0x210
[<00000000001be0b0>] console_unlock+0x3e0/0x4e8
[<00000000001be450>] vprintk_emit+0x298/0x6e0
[<00000000005aa210>] dev_vprintk_emit+0xe0/0x1a8
[<00000000005aa320>] dev_printk_emit+0x48/0x50
[<00000000005aa390>] __dev_printk+0x68/0xb0
[<00000000005aa7c2>] _dev_info+0x62/0x70
[<0000000000657bf0>] qeth_l2_send_setmac_cb+0xd0/0x190
[<0000000000651a1e>] qeth_send_control_data_cb+0x3a6/0x6a8
[<0000000000655546>] qeth_irq+0x1a6/0xac0
[<000000000060a0ac>] ccw_device_call_handler+0xa4/0xc0
[<0000000000608b62>] ccw_device_irq+0x5a/0x190
[<00000000005fd1ca>] do_cio_interrupt+0xca/0x108
[<00000000001c0a2e>] handle_irq_event_percpu+0x5e/0x378
[<00000000001c46fc>] handle_percpu_irq+0x6c/0x98
[<00000000001c0066>] generic_handle_irq+0x46/0x68
[<000000000010b5b6>] do_IRQ+0x5e/0x88
[<00000000007cf304>] io_call+0x6/0x20
[<000000000064c63a>] qeth_send_control_data+0x322/0x570
([<000000000064c50e>] qeth_send_control_data+0x1f6/0x570)
[<0000000000651db2>] qeth_send_ipa_cmd+0x92/0x120
[<000000000065b310>] __qeth_l2_set_online+0x170/0xaa8
[<000000000060ebb6>] ccwgroup_set_online+0x56/0x90
[<000000000060ef96>] ccwgroup_online_store+0xd6/0xe0
[<000000000033d11a>] kernfs_fop_write+0x10a/0x188
[<00000000002bbd00>] vfs_write+0x98/0x1c0
[<00000000002bc8a0>] SyS_write+0x60/0xd0
[<00000000007cee3a>] sysc_nr_ok+0x22/0x28
[<000003fffd0c3f28>] 0x3fffd0c3f28

Reported-by: Heiko Carstens <heiko.carstens@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 10:48:28 +02:00
..
airq.c s390/airq: add support for irq ranges 2014-02-21 08:50:22 +01:00
blacklist.c s390/blacklist: Perform subchannel scan only when needed 2013-12-16 14:37:43 +01:00
blacklist.h
ccwgroup.c s390: use device_remove_file_self() instead of device_schedule_callback() 2014-02-07 15:42:41 -08:00
ccwreq.c s390/lowcore: replace lowcore irb array with a per-cpu variable 2014-05-28 10:39:16 +02:00
chp.c s390/cio: fix multiple structure definitions 2014-05-20 08:58:53 +02:00
chp.h s390/cio: fix multiple structure definitions 2014-05-20 08:58:53 +02:00
chsc_sch.c s390/lowcore: replace lowcore irb array with a per-cpu variable 2014-05-28 10:39:16 +02:00
chsc_sch.h
chsc.c s390/chsc: fix SEI usage on old FW levels 2014-04-17 12:46:28 +02:00
chsc.h s390/cio: fix multiple structure definitions 2014-05-20 08:58:53 +02:00
cio_debug.h
cio.c s390/cio: silence lockdep warning 2014-06-10 10:48:28 +02:00
cio.h s390/lowcore: replace lowcore irb array with a per-cpu variable 2014-05-28 10:39:16 +02:00
cmf.c s390: replace strict_strtoul() with kstrtoul() 2013-08-22 12:20:00 +02:00
crw.c s390/comments: unify copyright messages and remove file names 2012-07-20 11:15:04 +02:00
css.c s390/css: Prevent unnecessary allocation in subchannel loop 2013-12-16 14:37:42 +01:00
css.h s390/cio: Delay scan for newly available I/O devices 2013-12-16 14:37:41 +01:00
device_fsm.c s390/lowcore: replace lowcore irb array with a per-cpu variable 2014-05-28 10:39:16 +02:00
device_id.c s390/comments: unify copyright messages and remove file names 2012-07-20 11:15:04 +02:00
device_ops.c s390/cio: fix multiple structure definitions 2014-05-20 08:58:53 +02:00
device_pgid.c s390/cio: handle unknown pgroup state 2013-02-14 15:55:09 +01:00
device_status.c s390/comments: unify copyright messages and remove file names 2012-07-20 11:15:04 +02:00
device.c s390/cio: fix irq stats for early interrupts on ccw consoles 2014-02-21 08:50:13 +01:00
device.h s390/cio: fix early init counter usage 2013-04-17 14:07:33 +02:00
eadm_sch.c s390/lowcore: replace lowcore irb array with a per-cpu variable 2014-05-28 10:39:16 +02:00
eadm_sch.h s390/eadm_sch: improve quiesce handling 2013-10-24 17:16:58 +02:00
fcx.c [S390] drivers: Correct size given to memset 2009-12-18 17:43:32 +01:00
idset.c s390/cio: Use BITS_TO_LONGS() instead of __BITOPS_WORDS() 2013-04-17 14:07:29 +02:00
idset.h s390/css: stop stsch loop after cc 3 2012-10-18 17:50:08 +02:00
io_sch.h s390/cio: dont abort verification after missing irq 2013-02-14 15:55:07 +01:00
ioasm.h [S390] cio: move asms to generic header 2011-03-15 17:08:23 +01:00
isc.c
itcw.c [S390] cio: reduce memory consumption of itcw structures 2011-01-05 12:47:29 +01:00
Makefile s390/cio: add eadm subchannel driver 2012-09-26 15:45:00 +02:00
orb.h s390: add eadm related structures 2012-09-26 15:44:57 +02:00
qdio_debug.c constify a bunch of struct file_operations instances 2013-04-09 14:16:20 -04:00
qdio_debug.h s390/s390dbf: use debug_level_enabled() where applicable 2013-10-24 17:16:54 +02:00
qdio_main.c s390/qdio: correct program-controlled interruption checking 2014-01-29 09:07:50 +01:00
qdio_setup.c s390/qdio: cleanup chsc SSQD usage 2013-06-26 21:10:14 +02:00
qdio_thinint.c s390/airq: simplify adapter interrupt code 2013-06-26 21:10:28 +02:00
qdio.h s390/qdio: for_each macro correctness 2014-01-29 09:07:50 +01:00
scm.c s390/scm_block: do not hide eadm subchannel dependency 2013-11-15 14:08:42 +01:00