Re: Linux Virtual SCSI HBAs and Virtual disks

[Aboo Valappil <aboo@aboo.org>]

Also, the modified version is available in 
http://vscsihba.aboo.org/vscsihbav202.tgz.
I actually uses the "openers" field in scsi_disk to find out if anyone 
has the scsi_device open or not.

Aboo


Aboo

Aboo Valappil wrote:
> Hi Doug Gilbert,
>
> sorry for the late reply. I am in the process of implementing sense 
> code and I will make it available.
>
> I tried the sdparms and it failed not due to lack of sense code and 
> status. What happened was that the user space SCSI target died due to 
> a unsupported SCSI command (bug in user space target). When it 
> crashed, the SCSI disk served by that user space target was opened by 
> sdparms. The driver removed the scsi_host which was attached to user 
> space target, thinking that the last registered user space part died. 
> I think those stack traces are due to the EH thread trying perform 
> some sort of recovery on SCSI command, but the scsi host has been 
> removed!
>
> To prevent this, I implemented some checks. When the last user space 
> application attached to the scsi_host, the driver will check to make 
> sure that there is no open SCSI devices on that scsi_host. If there is 
> some devices open, it will not remove the scsi_host. This kind of 
> approach should be ok because my design supports re-attaching a new 
> user space target with an existing scsi_host. The design also allows 
> to start multiple user space target to serve one scsi_host in the 
> kernel and there is no issue at all even if one dies. Whoever gets the 
> SCSI command will serve it and sleep if nothing available.
>
> Thanks
>
> Aboo
>
>
> Douglas Gilbert wrote:
>> Aboo Valappil wrote:
>>  
>>> Hi All,
>>>
>>> Thanks everyone to have a look at this.
>>>
>>> I think i modified to have the latest kernel support. Unfortunately I
>>> could not test it with 2.6.20 kernel due to some issues in my laptop 
>>> and
>>> 2.6.20 kernel. But it should work with 2.6.20 with this modification.
>>>
>>> The modified version is available through
>>> http://vscsihba.aboo.org/vscsihbav202.tgz.
>>>
>>> 1. I fixed the kmem_cache issue for sure.
>>> 2. I think i got around with INIT_WORK ... Made the following
>>> modifications ...
>>>     
>>
>> Perhaps you could get some of my scsi tools (e.g.
>> sdparm and sg3_utils) and make sure that vscsihba
>> can handle everything they can throw at it.
>> If the user space doesn't support a SCSI command then
>> your driver should fail gracefully (i.e. CHECK CONDITION,
>> etc).
>>
>> Here is a worrying example: sdparm sends an INQUIRY
>> and a couple of MODE SENSE(10) commands to a device.
>> /dev/sda was created by your script:
>> $ ./start_target.sh id=3 -files zz_lun0
>>
>> $ sdparm /dev/sda
>>     /dev/sda: VirtualH  VHD               0
>> <long wait>
>> $
>>
>>
>> However dmesg showed this:
>>
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> sd 0:0:0:0: SCSI error: return code = 0x00000002
>> end_request: I/O error, dev sda, sector 10240
>> Buffer I/O error on device sda, logical block 10240
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> sd 0:0:0:0: SCSI error: return code = 0x00000002
>> end_request: I/O error, dev sda, sector 10240
>> Buffer I/O error on device sda, logical block 10240
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> sd 0:0:0:0: SCSI error: return code = 0x00000002
>> end_request: I/O error, dev sda, sector 10240
>> Buffer I/O error on device sda, logical block 10240
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> sd 0:0:0:0: SCSI error: return code = 0x00000002
>> end_request: I/O error, dev sda, sector 10240
>> Buffer I/O error on device sda, logical block 10240
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> sd 0:0:0:0: SCSI error: return code = 0x00000002
>> end_request: I/O error, dev sda, sector 10240
>> Buffer I/O error on device sda, logical block 10240
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> vscsihba:3: In Reset Device
>> sd 0:0:0:0: SCSI error: return code = 0x00000002
>> end_request: I/O error, dev sda, sector 10240
>> Buffer I/O error on device sda, logical block 10240
>> BUG: at kernel/sched.c:3388 sub_preempt_count()
>>  [<e1bf029c>] scsitap_eh_abort+0x1c/0x90 [vscsihba]
>>  [<c024fe22>] scsi_error_handler+0x3e2/0xbe0
>>  [<c02d74f1>] __sched_text_start+0x2f1/0x660
>>  [<c024fa40>] scsi_error_handler+0x0/0xbe0
>>  [<c0131679>] kthread+0xa9/0xe0
>>  [<c01315d0>] kthread+0x0/0xe0
>>  [<c0103d0f>] kernel_thread_helper+0x7/0x18
>>  =======================
>> vscsihba:3: Abortng command serial number : 94
>> BUG: scheduling while atomic: scsi_eh_0/0x00000001/4749
>>  [<c02d7684>] __sched_text_start+0x484/0x660
>>  [<c013183b>] autoremove_wake_function+0x1b/0x50
>>  [<c01264a8>] lock_timer_base+0x28/0x70
>>  [<c01265f2>] __mod_timer+0x92/0xd0
>>  [<c02d826b>] schedule_timeout+0x4b/0xd0
>>  [<c01269c0>] process_timeout+0x0/0x10
>>  [<c02d7bbc>] wait_for_completion_timeout+0x9c/0x130
>>  [<c0119ee0>] default_wake_function+0x0/0x10
>>  [<c024f3c9>] scsi_send_eh_cmnd+0x1b9/0x390
>>  [<c011df3e>] vprintk+0x1fe/0x3a0
>>  [<c024f805>] scsi_delete_timer+0x15/0x60
>>  [<c024f624>] scsi_eh_tur+0x34/0xa0
>>  [<c024fe69>] scsi_error_handler+0x429/0xbe0
>>  [<c02d74f1>] __sched_text_start+0x2f1/0x660
>>  [<c024fa40>] scsi_error_handler+0x0/0xbe0
>>  [<c0131679>] kthread+0xa9/0xe0
>>  [<c01315d0>] kthread+0x0/0xe0
>>  [<c0103d0f>] kernel_thread_helper+0x7/0x18
>>  =======================
>> vscsihba:3: Abortng command serial number : 95
>> vscsihba:3: In Reset Device
>> BUG: scheduling while atomic: scsi_eh_0/0x00000001/4749
>>  [<c02d7684>] __sched_text_start+0x484/0x660
>>  [<c011df3e>] vprintk+0x1fe/0x3a0
>>  [<c01264a8>] lock_timer_base+0x28/0x70
>>  [<c01265f2>] __mod_timer+0x92/0xd0
>>  [<c02d826b>] schedule_timeout+0x4b/0xd0
>>  [<c01269c0>] process_timeout+0x0/0x10
>>  [<c02d7bbc>] wait_for_completion_timeout+0x9c/0x130
>>  [<c0119ee0>] default_wake_function+0x0/0x10
>>  [<c024f3c9>] scsi_send_eh_cmnd+0x1b9/0x390
>>  [<c024f805>] scsi_delete_timer+0x15/0x60
>>  [<c024f624>] scsi_eh_tur+0x34/0xa0
>>  [<e1bf00cd>] scsitap_eh_device_reset+0x1d/0x30 [vscsihba]
>>  [<c02503a8>] scsi_error_handler+0x968/0xbe0
>>  [<c02d74f1>] __sched_text_start+0x2f1/0x660
>>  [<c024fa40>] scsi_error_handler+0x0/0xbe0
>>  [<c0131679>] kthread+0xa9/0xe0
>>  [<c01315d0>] kthread+0x0/0xe0
>>  [<c0103d0f>] kernel_thread_helper+0x7/0x18
>>  =======================
>> vscsihba:3: Abortng command serial number : 96
>> vscsihba:3: In Reset Host
>> BUG: scheduling while atomic: scsi_eh_0/0x00000001/4749
>>  [<c02d7684>] __sched_text_start+0x484/0x660
>>  [<c01264a8>] lock_timer_base+0x28/0x70
>>  [<c01265f2>] __mod_timer+0x92/0xd0
>>  [<c02d826b>] schedule_timeout+0x4b/0xd0
>>  [<c01269c0>] process_timeout+0x0/0x10
>>  [<c01273d5>] msleep+0x25/0x30
>>  [<c024efb1>] scsi_try_host_reset+0xa1/0xd0
>>  [<c0250150>] scsi_error_handler+0x710/0xbe0
>>  [<c02d74f1>] __sched_text_start+0x2f1/0x660
>>  [<c024fa40>] scsi_error_handler+0x0/0xbe0
>>  [<c0131679>] kthread+0xa9/0xe0
>>  [<c01315d0>] kthread+0x0/0xe0
>>  [<c0103d0f>] kernel_thread_helper+0x7/0x18
>>  =======================
>> BUG: scheduling while atomic: scsi_eh_0/0x00000001/4749
>>  [<c02d7684>] __sched_text_start+0x484/0x660
>>  [<c01264a8>] lock_timer_base+0x28/0x70
>>  [<c01265f2>] __mod_timer+0x92/0xd0
>>  [<c02d826b>] schedule_timeout+0x4b/0xd0
>>  [<c01269c0>] process_timeout+0x0/0x10
>>  [<c02d7bbc>] wait_for_completion_timeout+0x9c/0x130
>>  [<c0119ee0>] default_wake_function+0x0/0x10
>>  [<c024f3c9>] scsi_send_eh_cmnd+0x1b9/0x390
>>  [<c02d74f1>] __sched_text_start+0x2f1/0x660
>>  [<c01265f2>] __mod_timer+0x92/0xd0
>>  [<c02d8272>] schedule_timeout+0x52/0xd0
>>  [<c024f624>] scsi_eh_tur+0x34/0xa0
>>  [<c02501a0>] scsi_error_handler+0x760/0xbe0
>>  [<c02d74f1>] __sched_text_start+0x2f1/0x660
>>  [<c024fa40>] scsi_error_handler+0x0/0xbe0
>>  [<c0131679>] kthread+0xa9/0xe0
>>  [<c01315d0>] kthread+0x0/0xe0
>>  [<c0103d0f>] kernel_thread_helper+0x7/0x18
>>  =======================
>> vscsihba:3: Abortng command serial number : 97
>> sd 0:0:0:0: scsi: Device offlined - not ready after error recovery
>> BUG: scheduling while atomic: scsi_eh_0/0x00000001/4749
>>  [<c02d7684>] __sched_text_start+0x484/0x660
>>  [<c013aa11>] module_put+0x31/0x60
>>  [<c024bd6e>] scsi_device_put+0x3e/0x40
>>  [<c024be5f>] __scsi_iterate_devices+0x6f/0x90
>>  [<c024fa86>] scsi_error_handler+0x46/0xbe0
>>  [<c024fa40>] scsi_error_handler+0x0/0xbe0
>>  [<c0131679>] kthread+0xa9/0xe0
>>  [<c01315d0>] kthread+0x0/0xe0
>>  [<c0103d0f>] kernel_thread_helper+0x7/0x18
>>  =======================
>>
>>
>> Doug Gilbert
>>   
>
>