[dm-devel] [PATCH] MD: Add del_timer_sync to mddev_suspend (fix nasty panic)

[Brassow Jonathan]

On May 16, 2012, at 7:50 PM, NeilBrown wrote:

> On Tue, 15 May 2012 23:06:14 -0500 Jonathan Brassow <jbrassow at redhat.com>
> wrote:
> 
>> Neil,
>> 
>> I've been seeing some really bad panics take place on dm-raid.c.  I've
>> found that it is because the mddev->safemode_timer is firing after the
>> mddev structure has been freed.  I've attached a patch to fix the
>> problem below, but I have some questions (outlined in the patch header).
>> I also have a debugging patch that prints something during each of the
>> suspend stages and when md_write_end resets the timer so that you can
>> see the problem in action - let me know if you want that patch also.
>> 
>> brassow
> 
> Hi Jon,
> thanks for the patch.  It looks simple and can clearly fix a problem
> so at this point in the cycle I propose to submit it to Linus as-is, even
> though I'm not convinced it is perfect, and you didn't give me a s-o-b line.
> See more blow.

Thanks Neil.

> <pet peeve>.
> No Signed-off-by: line?  why is that.
> 
> "Signed-off-by" *only* means "I certify that I have any necessary right to
> submit this patch, and I agree to it being used in the way that all other
> code in this project can be used" - only with more words.  See the Developer's
> Certificate of Origin 1.1
> 
> Refusing to add a Signed-off-by: because you don't think the code is "ready"
> yet in some sense is just plain wrong.  I never ever want to even see a patch
> that doesn't have Signed-off-by, because I don't know if I've been given
> permission to use it.
> 
> Certainly add an 'RFC-by' if you want to say something about the quality of
> the patch, but don't for that reason exclude the signed-off-by
> </pet peeve>

"RFC-by" must be some overly clever thing I thought up or saw at one point.  i can certainly break that habit.  I had seen that possibly setting 'mddev->safemode = 2' might be a possible solution.  I was also a bit confused if I should pull the 'del_timer_sync' from 'md_stop_writes'.  This is why I put the RFC in there, but I see your meaning.

Thanks,
 brassow
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