• Christof Schmitt's avatar
    [SCSI] zfcp: Issue FCP command without holding SCSI host_lock · e55f8753
    Christof Schmitt authored
    Interrupting the connection to the FCP channel while I/O requests are
    being issued can lead to this deadlock. scsi_dispatch_cmd already
    holds the host_lock while the recovery trigger tries to acquire the
    host_lock again when iterating through the scsi_devices.
    
     INFO: lockdep is turned off.
     BUG: spinlock lockup on CPU#1, blast/9660, 0000000078f38878
     CPU: 1 Not tainted 2.6.35.7SWEN2 #2
     Process blast (pid: 9660, task: 0000000071f75940, ksp: 0000000074393ac0)
            0000000074393640 00000000743935c0 0000000000000002 0000000000000000
            0000000074393660 00000000743935d8 00000000743935d8 00000000005590c2
            0000000000000000 0000000078f38878 0000000026ede800 0000000078f38878
            000000000000000d 040000000000000c 0000000074393628 0000000000000000
            0000000000000000 0000000000100b2a 00000000743935c0 0000000074393600
     Call Trace:
     ([<0000000000100a32>] show_trace+0xee/0x144)
      [<00000000003be202>] do_raw_spin_lock+0x112/0x178
      [<000000000055d408>] _raw_spin_lock_irqsave+0x90/0xb0
      [<00000000003f1514>] __scsi_iterate_devices+0x38/0xbc
      [<00000000004849b0>] zfcp_erp_clear_adapter_status+0xd0/0x16c
      [<000000000048587a>] zfcp_erp_adapter_reopen+0x3a/0xb4
      [<0000000000489812>] zfcp_fsf_req_send+0x166/0x180
      [<000000000048c8d6>] zfcp_fsf_fcp_cmnd+0x272/0x408
      [<000000000048f864>] zfcp_scsi_queuecommand+0x11c/0x1e0
      [<00000000003f1f2a>] scsi_dispatch_cmd+0x1d6/0x324
      [<00000000003f9910>] scsi_request_fn+0x42c/0x56c
      [<00000000003828ae>] __blk_run_queue+0x86/0x140
      [<000000000037f742>] elv_insert+0x11a/0x208
      [<000000000038104c>] blk_insert_cloned_request+0x84/0xe4
      [<000003c0032b7c64>] dm_dispatch_request+0x6c/0x94 [dm_mod]
      [<000003c0032b7d5c>] map_request+0xd0/0x100 [dm_mod]
      [<000003c0032b9a78>] dm_request_fn+0xec/0x1bc [dm_mod]
      [<0000000000382c0e>] generic_unplug_device+0x5a/0x6c
      [<000003c0032b7f98>] dm_unplug_all+0x74/0x9c [dm_mod]
      [<00000000001d1272>] sync_page+0x76/0x9c
      [<00000000001d12ba>] sync_page_killable+0x22/0x60
      [<000000000055a768>] __wait_on_bit_lock+0xc0/0x124
      [<00000000001d1140>] __lock_page_killable+0x78/0x84
      [<00000000001d351c>] generic_file_aio_read+0x5a4/0x7e8
      [<0000000000228ec0>] do_sync_read+0xc8/0x12c
      [<0000000000229edc>] vfs_read+0xac/0x1ac
      [<000000000022a0d8>] SyS_read+0x58/0xa8
      [<00000000001146de>] sysc_noemu+0x10/0x16
      [<00000200000493c4>] 0x200000493c4
     INFO: lockdep is turned off.
    
    Call zfcp_fsf_fcp_cmnd without the host_lock and disable the
    interrupts when acquiring the req_q_lock. According to the patch
    description in "[PATCH] Eliminate error handler overload of the SCSI
    serial number", the serial_number is not used, so simply drop the
    queuecommand wrapper function and run zfcp_scsi_queuecommand without
    holding the host_lock.
    Reviewed-by: default avatarSwen Schillig <swen@vnet.ibm.com>
    Signed-off-by: default avatarChristof Schmitt <christof.schmitt@de.ibm.com>
    Signed-off-by: default avatarJames Bottomley <James.Bottomley@suse.de>
    e55f8753
zfcp_fsf.c 66.6 KB