Re: [PATCH 1/1]: qla2xxx: dpc thread can execute before scsi host has been added

[Michael Reed <mdr@sgi.com>]

As there has been some discussion about what tree other qla2xxx
patches should apply, I'd like to add my $.02 and suggest that, if
possible, this patch should be applied to rc-fixes.

Thanks,
 Mike

Giridhar Malavali wrote:
> Thanks Michael,
> 
> Acked-by: Giridhar Malavali <giridhar.malavali@qlogic.com>
> 
> On Dec 2, 2009, at 7:11 AM, Michael Reed wrote:
> 
>> Fix crash in qla2x00_fdmi_register() due to the dpc
>> thread executing before the scsi host has been fully
>> added.
>>
>> Unable to handle kernel NULL pointer dereference (address  
>> 00000000000001d0)
>> qla2xxx_7_dpc[4140]: Oops 8813272891392 [1]
>>
>> Call Trace:
>> [<a000000100016910>] show_stack+0x50/0xa0
>>                                sp=e00000b07c59f930  
>> bsp=e00000b07c591400
>> [<a000000100017180>] show_regs+0x820/0x860
>>                                sp=e00000b07c59fb00  
>> bsp=e00000b07c5913a0
>> [<a00000010003bd60>] die+0x1a0/0x2e0
>>                                sp=e00000b07c59fb00  
>> bsp=e00000b07c591360
>> [<a0000001000681a0>] ia64_do_page_fault+0x8c0/0x9e0
>>                                sp=e00000b07c59fb00  
>> bsp=e00000b07c591310
>> [<a00000010000c8e0>] ia64_native_leave_kernel+0x0/0x270
>>                                sp=e00000b07c59fb90  
>> bsp=e00000b07c591310
>> [<a000000207197350>] qla2x00_fdmi_register+0x850/0xbe0 [qla2xxx]
>>                                sp=e00000b07c59fd60  
>> bsp=e00000b07c591290
>> [<a000000207171570>] qla2x00_configure_loop+0x1930/0x34c0 [qla2xxx]
>>                                sp=e00000b07c59fd60  
>> bsp=e00000b07c591128
>> [<a0000002071732b0>] qla2x00_loop_resync+0x1b0/0x2e0 [qla2xxx]
>>                                sp=e00000b07c59fdf0  
>> bsp=e00000b07c5910c0
>> [<a000000207166d40>] qla2x00_do_dpc+0x9a0/0xce0 [qla2xxx]
>>                                sp=e00000b07c59fdf0  
>> bsp=e00000b07c590fa0
>> [<a0000001000d5bb0>] kthread+0x110/0x140
>>                                sp=e00000b07c59fe00  
>> bsp=e00000b07c590f68
>> [<a000000100014a30>] kernel_thread_helper+0xd0/0x100
>>                                sp=e00000b07c59fe30  
>> bsp=e00000b07c590f40
>> [<a00000010000a4c0>] start_kernel_thread+0x20/0x40
>>                                sp=e00000b07c59fe30  
>> bsp=e00000b07c590f40
>>
>> crash> dis a000000207197350
>> 0xa000000207197350 <qla2x00_fdmi_register+2128>:        [MMI]        
>> ld1 r45=[r14];;
>> crash> scsi_qla_host.host 0xe00000b058c73ff8
>>  host = 0xe00000b058c73be0,
>> crash> Scsi_Host.shost_data 0xe00000b058c73be0
>>  shost_data = 0x0,  <<<<<<<<<<<
>>
>>
>> The fc_transport fc_* workqueue threads have yet to be created.
>>
>> crash> ps | grep _7
>>   3891      2   2  e00000b075c80000  IN   0.0       0      0   
>> [scsi_eh_7]
>>   4140      2   3  e00000b07c590000  RU   0.0       0      0   
>> [qla2xxx_7_dpc]
>>
>> The thread creating adding the Scsi_Host is blocked due to other
>> activity in sysfs.
>>
>> crash> bt 3762
>> PID: 3762   TASK: e00000b071e70000  CPU: 3   COMMAND: "modprobe"
>> #0 [BSP:e00000b071e71548] schedule at a000000100727e00
>> #1 [BSP:e00000b071e714c8] __mutex_lock_slowpath at a0000001007295a0
>> #2 [BSP:e00000b071e714a8] mutex_lock at a000000100729830
>> #3 [BSP:e00000b071e71478] sysfs_addrm_start at a0000001002584f0
>> #4 [BSP:e00000b071e71440] create_dir at a000000100259350
>> #5 [BSP:e00000b071e71410] sysfs_create_subdir at a000000100259510
>> #6 [BSP:e00000b071e713b0] internal_create_group at a00000010025c880
>> #7 [BSP:e00000b071e71388] sysfs_create_group at a00000010025cc50
>> #8 [BSP:e00000b071e71368] dpm_sysfs_add at a000000100425050
>> #9 [BSP:e00000b071e71310] device_add at a000000100417d90
>> #10 [BSP:e00000b071e712d8] scsi_add_host at a00000010045a380
>> #11 [BSP:e00000b071e71268] qla2x00_probe_one at a0000002071be950
>> #12 [BSP:e00000b071e71248] local_pci_probe at a00000010032e490
>> #13 [BSP:e00000b071e71218] pci_device_probe at a00000010032ecd0
>> #14 [BSP:e00000b071e711d8] driver_probe_device at a00000010041d480
>> #15 [BSP:e00000b071e711a8] __driver_attach at a00000010041d6e0
>> #16 [BSP:e00000b071e71170] bus_for_each_dev at a00000010041c240
>> #17 [BSP:e00000b071e71150] driver_attach at a00000010041d0a0
>> #18 [BSP:e00000b071e71108] bus_add_driver at a00000010041b080
>> #19 [BSP:e00000b071e710c0] driver_register at a00000010041dea0
>> #20 [BSP:e00000b071e71088] __pci_register_driver at a00000010032f610
>> #21 [BSP:e00000b071e71058] (unknown) at a000000207200270
>> #22 [BSP:e00000b071e71018] do_one_initcall at a00000010000a9c0
>> #23 [BSP:e00000b071e70f98] sys_init_module at a0000001000fef00
>> #24 [BSP:e00000b071e70f98] ia64_ret_from_syscall at a00000010000c740
>>
>> So, it appears that qla2xxx dpc thread is moving forward before the
>> scsi host has been completely added.
>>
>> This patch moves the setting of the init_done (and online) flag to
>> after the call to scsi_add_host() to hold off the dpc thread.
>>
>> Found via large lun count testing using 2.6.31.
>>
>> Signed-off-by: Michael Reed <mdr@sgi.com>
>>
>>
>> --- linux-2.6.32-rc8/drivers/scsi/qla2xxx/qla_os.c	2009-11-19  
>> 16:32:38.000000000 -0600
>> +++ linux-2.6.32-rc8-modified/drivers/scsi/qla2xxx/qla_os.c	 
>> 2009-12-02 08:46:04.962724212 -0600
>> @@ -2016,13 +2016,13 @@ skip_dpc:
>> 	DEBUG2(printk("DEBUG: detect hba %ld at address = %p\n",
>> 	    base_vha->host_no, ha));
>>
>> -	base_vha->flags.init_done = 1;
>> -	base_vha->flags.online = 1;
>> -
>> 	ret = scsi_add_host(host, &pdev->dev);
>> 	if (ret)
>> 		goto probe_failed;
>>
>> +	base_vha->flags.init_done = 1;
>> +	base_vha->flags.online = 1;
>> +
>> 	ha->isp_ops->enable_intrs(ha);
>>
>> 	scsi_scan_host(host);
>> --
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