How is supposed to be protected the units list?

[Attilio Rao]

2010/3/12 Alexander Motin <mav at freebsd.org>:
> Attilio Rao wrote:
>> 2010/3/5 Attilio Rao <attilio at freebsd.org>:
>>> 2010/3/4 Matthew Jacob <mj at feral.com>:
>>>> The referred to patch at least got me out of panic case :-)..
>>>>
>>>> http://people.freebsd.org/~mjacob/scsi_da.c.patch
>>> Yes, honestly the main intent of this patch is to offer a stable
>>> ground for correct handling of periph. When looking about refcounting
>>> them correctly, the main problem is that there was no initial
>>> condition assuring safety, and the initial patch should address this,
>>> but I'm sure there are places where periph refcount is not handled
>>> correctly and this may be one.
>>
>> So, as long as it seems nobody had a strong argument against this
>> patch, what do you think about me committing it?
>> We can further refine later if we think it is the case.
>>
>> Also, I think that Matt's patch should be committed just after this
>> one (and possibly we should investigate a similar add-on for the ata
>> counterpart too?).
>
> I have already told my opinion, that second lock may be not needed. I
> would like to think a bit more about both patches after getting back
> from the conference. Thanks,

If you don't want to use the second lock, you have to use xpt_lock in
all the other places anyways.
I think it can get messy in particular if linked to another aspect:
Another question, may be to integrate that locking paradigm directly
with reference count of periph.
It depends by if the periph can came from other parts as well.

Attilio


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