Re: [PATCH] x86: make oops_begin and oops_end equal

Neil Horman
2008-10-22T10:47:37Z

On Wed, Oct 22, 2008 at 12:18:41PM +0200, Alexander van Heukelum wrote:
> On Tue, 21 Oct 2008 10:45:05 -0400, "Neil Horman"
> <nhorman@tuxdriver.com> said:
> > On Mon, Oct 20, 2008 at 05:08:34PM +0200, Alexander van Heukelum wrote:
> > > Mostly use the x86_64 version of oops_begin() and oops_end() on
> > > i386 too. Changes to the original x86_64 version:
> > >
> > Hey, doing a sight review this am here. Didn't find anything major, but
> > I did
> > find a few little nits. comments inlie
>
> Hi Neil,
>
> Thanks for the review. I've sent a redone patch series just a moment
> ago, based on your comments. There was also another problem with these
> two patches: oops_end(flags, regs, signr) had special behaviour for
> regs=NULL that I did not consider before. The series has grown due
> to this issue...
>
> >> [...]
> > Hmm. I think this creates the same case that I just fixed in my initial
> > post. If we start using oops_end with this here, it may be possible to call
> > crash_kexec with the console_sem held. If that happens, we deadlock. I
> > think you should be able to move this clause up above the bust_spinlocks(0)
> > without any issue, and that would take care of that
>
> Indeed. The new series does exactly that.
>
> >> [...]
> > This undoes my previous patch. I realize your second patch fixes it
> > properly so the ordering is correct when oops_begin and oops_end are used, but if you
> > could rediff so this isn't here, I'd appreciate it. If these patches are
> > committed separately, you'll avoid having the tree in a state where that deadlock
> > can reoccur (even if it is just for one commit)
>
> Yeah, I quickly rediffed the patches I already had. The new series
> leaves
> it as is until die_nmi is replaced by the oops_begin/oops_end version.
>
> >> [...]
> > If you're going to add the crash_kexec here (which looking at the call
> > sites, makes sense to me), you should likely remove it from the critical section
> > of die and die_nmi, just to avoid the redundancy. Same issue as the 32 bit
> > version above applies, this needs to happen before you call bust_spinlocks(0).
>
> Indeed.
>
> > Fix those issues, and the rest looks good to me.
>
> I think I've done that ;).
>
> Thanks,
> Greetings,
> Alexander
>
> (I will probably not be able to respond to e-mail until after the
> weekend)
Copy that. Thanks for the quick turn-around.

Best
Neil

> --
> Alexander van Heukelum
> heukelum@fastmail.fm
>
> --
> http://www.fastmail.fm - mmm... Fastmail...
>
>

--
/****************************************************
* Neil Horman <nhorman@tuxdriver.com>
* Software Engineer, Red Hat
****************************************************/