Re: [PATCH 8/9] perf/breakpoint: Split breakpoint "check" and "commit"

Ingo Molnar
2018-05-15T06:57:53Z

* Peter Zijlstra <peterz@infradead.org> wrote:

> On Sun, May 06, 2018 at 09:19:54PM +0200, Frederic Weisbecker wrote:
> > arch/arm/include/asm/hw_breakpoint.h | 5 ++++-
> > arch/arm/kernel/hw_breakpoint.c | 22 +++-------------------
> > arch/arm64/include/asm/hw_breakpoint.h | 5 ++++-
> > arch/arm64/kernel/hw_breakpoint.c | 22 +++-------------------
> > arch/powerpc/include/asm/hw_breakpoint.h | 5 ++++-
> > arch/powerpc/kernel/hw_breakpoint.c | 22 +++-------------------
> > arch/sh/include/asm/hw_breakpoint.h | 5 ++++-
> > arch/sh/kernel/hw_breakpoint.c | 22 +++-------------------
> > arch/x86/include/asm/hw_breakpoint.h | 5 ++++-
> > arch/x86/kernel/hw_breakpoint.c | 23 +++--------------------
> > arch/xtensa/include/asm/hw_breakpoint.h | 5 ++++-
> > arch/xtensa/kernel/hw_breakpoint.c | 22 +++-------------------
>
> Because of those ^,
>
> > kernel/events/hw_breakpoint.c | 11 ++++++-----
>
> would it not make sense to have a prelimenary patch doing something
> like:
>
> __weak int hw_breakpoint_arch_check(struct perf_event *bp)
> {
> return arch_validate_hwbkpt_settings(bp);
> }
>
> __weak void hw_breakpoint_arch_commit(struct perf_event *bp)
> {
> }
>
> combined with this bit:
>
> > diff --git a/kernel/events/hw_breakpoint.c b/kernel/events/hw_breakpoint.c
> > index 6e28d28..6896ceeb 100644
> > --- a/kernel/events/hw_breakpoint.c
> > +++ b/kernel/events/hw_breakpoint.c
> > @@ -402,11 +402,12 @@ int dbg_release_bp_slot(struct perf_event *bp)
> >
> > static int validate_hw_breakpoint(struct perf_event *bp)
> > {
> > - int ret;
> > + int err;
> >
> > - ret = arch_validate_hwbkpt_settings(bp);
> > - if (ret)
> > - return ret;
> > + err = hw_breakpoint_arch_check(bp, &bp->attr);
> > + if (err)
> > + return err;
> > + hw_breakpoint_arch_commit(bp);
> >
> > if (arch_check_bp_in_kernelspace(bp)) {
> > if (bp->attr.exclude_kernel)
>
> And then convert the archs over one by one, and at the end remove the
> weak thingies entirely?

Makes sense.

The rest looks good to me - Frederic, once you implement Peter's uggestion I
suspect this series can be applied.

Thanks,

Ingo