Re: [patch 25/45] SCSI: sg: fix races during device removal

From: Tony Battersby
Date: Wed Apr 01 2009 - 11:18:48 EST


FUJITA Tomonori wrote:
> On Tue, 31 Mar 2009 18:15:33 -0700
> Chris Wright <chrisw@xxxxxxxxxxxx> wrote:
>
>
>> * Linus Torvalds (torvalds@xxxxxxxxxxxxxxxxxxxx) wrote:
>>
>>> On Wed, 1 Apr 2009, James Bottomley wrote:
>>>
>>>> I think we could wait a bit to see if any issues turn up in 2.6.30
>>>> testing. I think it should go in eventually, though.
>>>>
>>> Sure, that sounds sane. But right now it has very little extra testing, so
>>> wait with putting it into -stable at _least_ until after -rc1 release or
>>> something?
>>>
>> I'll drop it (meaning the three). James can you resend after they've
>> withstood the test of time?
>>
>
> I really want to push the patches as soon as possible. The bug that
> the 27/45 patch fixes has been for two months and I saw bug reports
> about it again and again:
>
> http://marc.info/?l=linux-kernel&m=123841463709919&w=2
>
>
My two patches (25/45 and 26/45) fix very old problems, so there is no
rush to get them into -stable for their own sake. However, Fujita's
patch (27/45) looks like it depends on my large patch (25/45), and it
fixes a regression present in 2.6.28 and 2.6.29. So we have to weigh
the need to fix a regression that affects multiple people against the
chance of introducing new regressions. Waiting until after 2.6.30-rc1
sounds reasonable to me, although I am not one of the people affected by
the regression fixed by Fujita's patch (since I am still using 2.6.27
-stable).

Another thing to consider is whether these patches should be included in
2.6.27 -stable. Fujita's patch (27/45) shouldn't be necessary since
2.6.27 doesn't have the regression. Omitting that patch removes the
dependency on my large patch (25/45), so we could question whether any
of these three patches should be included in 2.6.27. As Linus points
out, my large patch is way above the official size limit for -stable,
but on the other hand, perhaps we could assume that "good enough for
2.6.28.x and 2.6.29.x" implies "good enough for 2.6.27.x".

Finally, I should point out that the effectiveness of "[patch 26/45]
SCSI: sg: fix races with ioctl(SG_IO)" depends on the changes to
sg_rq_end_io() made by "[patch 25/45] SCSI: sg: fix races during device
removal", so the smaller patch 26/45 should not be applied by itself
without the large patch 25/45.

Tony Battersby
Cybernetics

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