Re: [PATCH] perf/x86/amd/core: always clear status for idx

[Sandipan Das <sandipan.das@amd.com>]

On 3/21/2023 5:03 PM, Breno Leitao wrote:
> The variable 'status' (which contains the unhandled overflow bits) is
> not being properly masked in some cases, displaying the following
> warning:
> 
>   WARNING: CPU: 156 PID: 475601 at arch/x86/events/amd/core.c:972 amd_pmu_v2_handle_irq+0x216/0x270
> 
> This seems to be happening because the loop is being continued before
> the status bit being unset, in case x86_perf_event_set_period()
> returns 0. This is also causing an inconsistency because the "handled"
> counter is incremented, but the status bit is not cleaned.
> 
> Move the bit cleaning together above, together when the "handled"
> counter is incremented.
> 
> Signed-off-by: Breno Leitao <leitao@debian.org>
> ---
>  arch/x86/events/amd/core.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/x86/events/amd/core.c b/arch/x86/events/amd/core.c
> index 8c45b198b62f..bccea57dee81 100644
> --- a/arch/x86/events/amd/core.c
> +++ b/arch/x86/events/amd/core.c
> @@ -923,6 +923,7 @@ static int amd_pmu_v2_handle_irq(struct pt_regs *regs)
>  
>  		/* Event overflow */
>  		handled++;
> +		status &= ~mask;
>  		perf_sample_data_init(&data, 0, hwc->last_period);
>  
>  		if (!x86_perf_event_set_period(event))
> @@ -933,8 +934,6 @@ static int amd_pmu_v2_handle_irq(struct pt_regs *regs)
>  
>  		if (perf_event_overflow(event, &data, regs))
>  			x86_pmu_stop(event, 0);
> -
> -		status &= ~mask;
>  	}
>  
>  	/*

Thanks for fixing this.

Reviewed-by: Sandipan Das <sandipan.das@amd.com>