Re: [patch 00/20] x86, ptrace, bts, hw-branch-tracer: fixes andcleanups

From: Markus Metzger
Date: Fri Apr 03 2009 - 13:45:26 EST


On Fri, 2009-04-03 at 17:36 +0200, Ingo Molnar wrote:
> * markus.t.metzger@xxxxxxxxx <markus.t.metzger@xxxxxxxxx> wrote:
>
> > Patches 1-5 fix races with context switching code when the branch
> > traced task is currently running.
> >
> > In the worst case, this might cause context switch code to access
> > freed memory or the tracing hardware to continue tracing into a
> > freed buffer. Both might crash the kernel.
> >
> > The first 4 patches apply to .29 using the below preparation
> > patch.
> >
> > The remaining patches fix bugs in the context of per-cpu tracing
> > (i.e. hw-branch-tracer) and pebs, add more selftest code, and do
> > some cleanups.
>
> Thanks - this looks pretty acceptable. Latest -git changed a lot of
> code in the same area (-mm bits went upstream), creating a lot of
> conflicts.
>
> To not prolongue this any longer (20 patches are difficult enough
> already to handle) i picked up your patches and resolved the
> conflicts in situ - mind having a look at the resulting
> tip:tracing/hw-branch-tracing branch - does the end result look sane
> to you?

Thanks,

The branch tracing bits in tip/tracing/hw-branch-tracing look good.
The kernel boots (after changes, see below) and my tests pass.

A defconfig build fails with a compile error, though:
In file included from net/core/skbuff.c:68:
include/trace/skb.h:7: error: expected â)â before â(â token
.....

Changing TP~ to TP_~ (as in tip/master) seems to do the trick.


> It would also be nice to address Peter's feedback about the mm.h
> detail and the locked-pages API - but we can do that on top.

I will address them, though not immediately (vacation).


thanks and regards,
markus.

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