freebsd-scsi Digest, Vol 359, Issue 6
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Today's Topics:
1. Re: How is supposed to be protected the units list? (Attilio Rao)
2. Re: How is supposed to be protected the units list?
(Matthew Jacob)
3. Re: How is supposed to be protected the units list?
(Alexander Motin)
4. Re: How is supposed to be protected the units list?
(Matthew Jacob)
5. Re: How is supposed to be protected the units list? (Attilio Rao)
6. Re: How is supposed to be protected the units list? (Ed Maste)
----------------------------------------------------------------------
Message: 1
Date: Fri, 12 Mar 2010 15:01:54 +0100
From: Attilio Rao <att...@freebsd.org>
Subject: Re: How is supposed to be protected the units list?
To: m...@feral.com, Alexander Motin <m...@freebsd.org>, "Justin T. Gibbs"
<gi...@freebsd.org>
Cc: freebs...@freebsd.org
Message-ID:
<3bbf2fe11003120601y3c4...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
2010/3/5 Attilio Rao <att...@freebsd.org>:
> 2010/3/4 Matthew Jacob <m...@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?).
Thanks,
Attilio
--
Peace can only be achieved by understanding - A. Einstein
------------------------------
Message: 2
Date: Fri, 12 Mar 2010 06:51:34 -0800
From: Matthew Jacob <m...@feral.com>
Subject: Re: How is supposed to be protected the units list?
To: freebs...@freebsd.org
Message-ID: <4B9A54F6...@feral.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
I'm okay with it at present.
> 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?).
>
> Thanks,
> Attilio
>
>
>
------------------------------
Message: 3
Date: Fri, 12 Mar 2010 21:11:22 +0200
From: Alexander Motin <m...@FreeBSD.org>
Subject: Re: How is supposed to be protected the units list?
To: Attilio Rao <att...@freebsd.org>
Cc: freebs...@freebsd.org, "Justin T. Gibbs" <gi...@freebsd.org>,
m...@feral.com
Message-ID: <4B9A91DA...@FreeBSD.org>
Content-Type: text/plain; charset=UTF-8
Attilio Rao wrote:
> 2010/3/5 Attilio Rao <att...@freebsd.org>:
>> 2010/3/4 Matthew Jacob <m...@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,
--
Alexander Motin
------------------------------
Message: 4
Date: Fri, 12 Mar 2010 11:19:08 -0800
From: Matthew Jacob <m...@feral.com>
Subject: Re: How is supposed to be protected the units list?
To: freebs...@freebsd.org
Message-ID: <4B9A93AC...@feral.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
That's a fair comment. There is at least one case where this additional
lock has helped. It probably needs rethinking a little later, but for
now it does seem to help people.
> 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,
>
>
------------------------------
Message: 5
Date: Fri, 12 Mar 2010 20:29:12 +0100
From: Attilio Rao <att...@freebsd.org>
Subject: Re: How is supposed to be protected the units list?
To: Alexander Motin <m...@freebsd.org>
Cc: freebs...@freebsd.org, "Justin T. Gibbs" <gi...@freebsd.org>,
m...@feral.com
Message-ID:
<3bbf2fe11003121129w69...@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
2010/3/12 Alexander Motin <m...@freebsd.org>:
> Attilio Rao wrote:
>> 2010/3/5 Attilio Rao <att...@freebsd.org>:
>>> 2010/3/4 Matthew Jacob <m...@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
--
Peace can only be achieved by understanding - A. Einstein
------------------------------
Message: 6
Date: Fri, 12 Mar 2010 19:41:49 -0500
From: Ed Maste <ema...@freebsd.org>
Subject: Re: How is supposed to be protected the units list?
Cc: freebs...@freebsd.org
Message-ID: <20100313004...@sandvine.com>
Content-Type: text/plain; charset=us-ascii
On Fri, Mar 12, 2010 at 11:19:08AM -0800, Matthew Jacob wrote:
> That's a fair comment. There is at least one case where this additional
> lock has helped. It probably needs rethinking a little later, but for
> now it does seem to help people.
Right, the change is an improvement over the status quo; we were
experiencing an easily reproducible panic from this issue that is solved
by this change. We can always change it again if a more optimal
soultion is proposed.
Thanks,
Ed
------------------------------
End of freebsd-scsi Digest, Vol 359, Issue 6
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