linux-kernel - Re: [PATCH] arm_pmu: Drop redundant armpmu->map_event() in armpmu_event

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Date:   Thu, 1 Dec 2022 12:24:35 +0000
From:   Mark Rutland <mark.rutland@....com>
To:     Anshuman Khandual <anshuman.khandual@....com>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm_pmu: Drop redundant armpmu->map_event() in
 armpmu_event_init()

On Wed, Nov 30, 2022 at 02:03:50PM +0530, Anshuman Khandual wrote:
> __hw_perf_event_init() already calls armpmu->map_event() callback, and also
> returns its error code including -ENOENT, along with a debug callout. Hence
> an additional armpmu->map_event() check for -ENOENT is redundant.

Hmm; it looks like this has been redundant since commit:

  e1f431b57ef9e4a6 ("ARM: perf: refactor event mapping")

... and was an oversight on my behalf.

This looks fine to me, so FWIW:

Acked-by: Mark Rutland <mark.rutland@....com>

Mark.

> 
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
> ---
> This applies on v6.1-rc6
> 
>  drivers/perf/arm_pmu.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
> index 6538cec1a601..4be6869005f1 100644
> --- a/drivers/perf/arm_pmu.c
> +++ b/drivers/perf/arm_pmu.c
> @@ -529,10 +529,6 @@ static int armpmu_event_init(struct perf_event *event)
>  			return -EOPNOTSUPP;
>  		}
>  	}
> -
> -	if (armpmu->map_event(event) == -ENOENT)
> -		return -ENOENT;
> -
>  	return __hw_perf_event_init(event);
>  }
>  
> -- 
> 2.25.1
>