[PATCH] zfcp: fix incorrect usage of erp_lock

[PATCH] zfcp: fix incorrect usage of erp_lock

  =================================
  [ INFO: inconsistent lock state ]
  ---------------------------------
  inconsistent {hardirq-on-W} -> {in-hardirq-W} usage.
  swapper/0 [HC1[1]:SC0[0]:HE0:SE1] takes:
   (&adapter->erp_lock){+-..}, at: [<000000000026c7f8>] zfcp_erp_async_handler+0x3c/0x70
  {hardirq-on-W} state was registered at:
    [<000000000005f33e>] __lock_acquire+0x30a/0xed0
    [<00000000000604ae>] lock_acquire+0x9a/0xc8
    [<000000000035a7ae>] _write_lock+0x4e/0x68
    [<000000000026d822>] zfcp_erp_adapter_strategy_generic+0x286/0xd94
    [<000000000026fd72>] zfcp_erp_strategy_do_action+0x91e/0x1a94
    [<0000000000271a3a>] zfcp_erp_thread+0x21a/0x1568
    [<0000000000019096>] kernel_thread_starter+0x6/0xc
    [<0000000000019090>] kernel_thread_starter+0x0/0xc
  irq event stamp: 12078
  hardirqs last  enabled at (12077): [<0000000000019416>] cpu_idle+0x206/0x250
  hardirqs last disabled at (12078): [<0000000000020458>] io_no_vtime+0xc/0x1c
  softirqs last  enabled at (12072): [<0000000000040b62>] __do_softirq+0x13a/0x180
  softirqs last disabled at (12059): [<000000000001fd58>] do_softirq+0xec/0xf0

  other info that might help us debug this:
  no locks held by swapper/0.

  stack backtrace:
  00000000012bb648 0000000000000002 0000000000000000 00000000012bb758
         00000000012bb6c0 0000000000399122 0000000000399122 0000000000016b0a
         0000000000000000 0000000000000001 0000000000000000 00000000004660e8
         0000000000000000 000000000000000d 00000000012bb6b8 00000000012bb730
         0000000000368b90 0000000000016b0a 00000000012bb6b8 00000000012bb708
  Call Trace:
  ([<0000000000016a26>] show_trace+0x76/0xdc)
   [<0000000000016b2c>] show_stack+0xa0/0xd0
   [<0000000000016b8a>] dump_stack+0x2e/0x3c
   [<000000000005e3da>] print_usage_bug+0x27e/0x290
   [<000000000005e934>] mark_lock+0x548/0x6c0
   [<000000000005fb0c>] __lock_acquire+0xad8/0xed0
   [<00000000000604ae>] lock_acquire+0x9a/0xc8
   [<000000000035a662>] _write_lock_irqsave+0x62/0x80
   [<000000000026c7f8>] zfcp_erp_async_handler+0x3c/0x70
   [<0000000000279178>] zfcp_fsf_req_dispatch+0xd8/0x1fa8
   [<000000000027e538>] zfcp_fsf_req_complete+0x104/0xe4c
   [<0000000000274534>] zfcp_qdio_reqid_check+0xf4/0x178
   [<000000000027469e>] zfcp_qdio_response_handler+0xe6/0x430
   [<0000000000219dd4>] tiqdio_thinint_handler+0xd20/0x213c
   [<000000000020229a>] do_adapter_IO+0xb2/0xc0
   [<0000000000206f32>] do_IRQ+0x136/0x16c
   [<0000000000020462>] io_no_vtime+0x16/0x1c
   [<0000000000019432>] cpu_idle+0x222/0x250
  ([<0000000000019416>] cpu_idle+0x206/0x250)
   [<000000000001405a>] rest_init+0x5a/0x68
   [<0000000000536998>] start_kernel+0x39c/0x3dc
   [<0000000000013046>] _stext+0x46/0x1000

Fix incorrect usage of erp_lock. Using the write_lock() variant is wrong,
since this might lead to deadlocks.

Acked-by: Andreas Herrmann <aherrman@de.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>