kernel_optimize_test/drivers/s390
Christof Schmitt 44a24cb373 [SCSI] zfcp: Change spin_lock_bh to spin_lock_irq to fix lockdep warning
With the change to use the data on the SCSI device, iterating through
all LUNs/scsi_devices takes the SCSI host_lock. This triggers warnings
from the lock dependency checker:

=========================================================
[ INFO: possible irq lock inversion dependency detected ]
2.6.34.1 #97
---------------------------------------------------------
chchp/3224 just changed the state of lock:
 (&(shost->host_lock)->rlock){-.-...}, at: [<00000000003a73f4>] __scsi_iterate_devices+0x38/0xbc
but this lock took another, HARDIRQ-unsafe lock in the past:
 (&(&qdio->req_q_lock)->rlock){+.-...}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this: [   24.972394] 2 locks held by chchp/3224:
 #0:  (&(sch->lock)->rlock){-.-...}, at: [<0000000000401efa>] do_IRQ+0xb2/0x1e4
 #1:  (&adapter->port_list_lock){.-....}, at: [<0000000000490302>] zfcp_erp_modify_adapter_status+0x9e/0x16c
[...]

=========================================================
[ INFO: possible irq lock inversion dependency detected ]
2.6.34.1 #98
---------------------------------------------------------
chchp/3235 just changed the state of lock:
 (&(shost->host_lock)->rlock){-.-...}, at: [<00000000003a73f4>] __scsi_iterate_devices+0x38/0xbc
but this lock took another, HARDIRQ-unsafe lock in the past:
 (&(&qdio->stat_lock)->rlock){+.-...}

and interrupts could create inverse lock ordering between them.

other info that might help us debug this:
2 locks held by chchp/3235:
 #0:  (&(sch->lock)->rlock){-.-...}, at: [<0000000000401efa>] do_IRQ+0xb2/0x1e4
 #1:  (&adapter->port_list_lock){.-.-..}, at: [<00000000004902f6>] zfcp_erp_modify_adapter_status+0x9e/0x16c
[...]

To stop this warning, change the request queue lock to disable irqs,
not only softirq. The changes are required only outside of the
critical "send fcp command" path.

Reviewed-by: Swen Schillig <swen@vnet.ibm.com>
Signed-off-by: Christof Schmitt <christof.schmitt@de.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
2010-09-16 22:54:19 -04:00
..
block [S390] dasd: fix format string types 2010-08-13 10:06:54 +02:00
char Input: sysrq - drop tty argument form handle_sysrq() 2010-08-21 00:34:45 -07:00
cio [S390] cio: use all available paths for some internal I/O 2010-08-09 18:12:54 +02:00
crypto [S390] avoid default_llseek in s390 drivers 2010-05-17 10:00:16 +02:00
kvm include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2010-08-13 10:38:12 -07:00
scsi [SCSI] zfcp: Change spin_lock_bh to spin_lock_irq to fix lockdep warning 2010-09-16 22:54:19 -04:00
Makefile [S390] split/move machine check handler code 2009-03-26 15:24:10 +01:00