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Re: Why the mce reverts in 4.16-rt?




On Wed, 11 Jul 2018 09:23:11 +0200
Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> wrote:

> On 2018-07-10 20:56:24 [-0400], Steven Rostedt wrote:
> > Hi Sebastian,  
> Hi Steven,
> 
> > I'm looking at backporting patches from 4.16-rt and noticed that you
> > have:
> > 
> > Revert "x86: Convert mce timer to hrtimer"
> > Revert "x86/mce: use swait queue for mce wakeups"
> > 
> > With no explanation to why they were reverted. When did things change?
> > Should this be 4.14-rt material?  
> 
> from the announce email:
> |    Changes since v4.16.8-rt2:
> |    
> |      - Drop two MCE related patches. They are no longer required since the
> |        timer wheel rework.

Thanks, still would have preferred a comment in the revert commit
message ;-)

> 
> The timer wheel rework made it possible to have a raw_spin_lock_t in the
> timer_list timer. The problem with MCE was that it enqueued a timer from
> hardirq context which is now possible. So the patches are no longer
> required. This revert does not fix a bug in v4.14 nor does it break
> anything.

OK, even though this doesn't fix anything, I think I'll still
backport it.

-- Steve