linux-kernel - Re: [kvm-riscv/for-next 1/2] drivers/perf: riscv: Remove the warning from stop function

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Date: Thu, 25 Apr 2024 13:22:08 -0700
From: Atish Patra <atishp@...shpatra.org>
To: Samuel Holland <samuel.holland@...ive.com>
Cc: Atish Patra <atishp@...osinc.com>, linux-kernel@...r.kernel.org, 
	Alexandre Ghiti <alexghiti@...osinc.com>, Andrew Jones <ajones@...tanamicro.com>, 
	Anup Patel <anup@...infault.org>, Conor Dooley <conor.dooley@...rochip.com>, 
	linux-riscv@...ts.infradead.org, kvm-riscv@...ts.infradead.org, 
	Mark Rutland <mark.rutland@....com>, Palmer Dabbelt <palmer@...belt.com>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Will Deacon <will@...nel.org>
Subject: Re: [kvm-riscv/for-next 1/2] drivers/perf: riscv: Remove the warning
 from stop function

On Thu, Apr 25, 2024 at 1:08 PM Samuel Holland
<samuel.holland@...ive.com> wrote:
>
> On 2024-04-25 6:29 PM, Atish Patra wrote:
> > The warning message was initially added just to indicate that counter
> > stop function is being called while the event is already stopped.
> >
> > However, we update the state to stopped case now in an overflow handler
> > after stopping the counter. If there is another child overflow handler
> > is registered (e.g kvm) it may call stop again which will trigger the
> > warning.
> >
> > Fixes : commit 22f5dac41004d ("drivers/perf: riscv: Implement SBI PMU snapshot function")
>
> This may be intentional, since you wanted these to be squashed, but this isn't
> the right format for a Fixes: tag (no space before ":" and no "commit"). Otherwise,
>

Yeah. Just wanted to be explicit as the commit is based on kvm-riscv
queue and not based on upstream commit.

> Reviewed-by: Samuel Holland <samuel.holland@...ive.com>
>
> > Signed-off-by: Atish Patra <atishp@...osinc.com>
> > ---
> >  drivers/perf/riscv_pmu.c | 2 --
> >  1 file changed, 2 deletions(-)
> >
> > diff --git a/drivers/perf/riscv_pmu.c b/drivers/perf/riscv_pmu.c
> > index 36d348753d05..78c490e0505a 100644
> > --- a/drivers/perf/riscv_pmu.c
> > +++ b/drivers/perf/riscv_pmu.c
> > @@ -191,8 +191,6 @@ void riscv_pmu_stop(struct perf_event *event, int flags)
> >       struct hw_perf_event *hwc = &event->hw;
> >       struct riscv_pmu *rvpmu = to_riscv_pmu(event->pmu);
> >
> > -     WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
> > -
> >       if (!(hwc->state & PERF_HES_STOPPED)) {
> >               if (rvpmu->ctr_stop) {
> >                       rvpmu->ctr_stop(event, 0);
>


-- 
Regards,
Atish