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 15:08:31 -0500
From: Samuel Holland <samuel.holland@...ive.com>
To: Atish Patra <atishp@...osinc.com>, linux-kernel@...r.kernel.org
Cc: Alexandre Ghiti <alexghiti@...osinc.com>,
 Andrew Jones <ajones@...tanamicro.com>, Anup Patel <anup@...infault.org>,
 Atish Patra <atishp@...shpatra.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 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,

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);