Re: [PATCH] target: Make transport_lookup_cmd_lun() locking IRQ-safe

[Kiran Patil <kiran.patil@intel.com>]

On 6/15/2011 10:25 AM, Nicholas A. Bellinger wrote:
> On Wed, 2011-06-15 at 10:22 -0700, Roland Dreier wrote:
>> On Wed, Jun 15, 2011 at 10:06 AM, Nicholas A. Bellinger
>> <nab@linux-iscsi.org>  wrote:
>>> Btw, I think the same type of conversion may need to happen for
>>> transport_lookup_tmr_lun() as well, as I believe qla_target.c can call
>>> this directly from interrupt context in certain situations.
>> Yes, I think I sent another mail about this... the reason I didn't just
>> send a patch is that transport_lookup_tmr_lun() ends with:
>>
>>          spin_lock(&se_tmr->tmr_dev->se_tmr_lock);
>>          list_add_tail(&se_tmr->tmr_list,&se_tmr->tmr_dev->dev_tmr_list);
>>          spin_unlock(&se_tmr->tmr_dev->se_tmr_lock);
>>
>> and indeed se_tmr_lock looks like it is taken with bare spin_lock()
>> in lots of places.
>>
> Actually, it's only two places:  core_tmr_release_req() and
> core_tmr_lun_reset()
>
>> Presumably se_tmr_lock is taken from process context sometimes?
>> So we would need to convert all those spin_lock()s to spin_lock_irq()
>> (or irqsave I guess).
>>
> Correct, both of the above are only every called from process context,
> so a simple conversion to spin_lock_irq() for these two, and
> spin_lock_irqsave() in transport_lookup_tmr_lun() should by sufficent..
Likewise, we need to do same change in function 
"transport_get_lun_for_tmr", specifically for tmr_lock. Please correct 
me if I am missing anything.
> --nab
>
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Thanks,
-- Kiran P.