linux-kernel - Re: [PATCH] perf/smmuv3: add a check of devm_add_action in smmu_pmu_setup

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Message-ID: <20230327112652.GA30874@willie-the-truck>
Date:   Mon, 27 Mar 2023 12:26:53 +0100
From:   Will Deacon <will@...nel.org>
To:     void0red <void0red@...il.com>
Cc:     mark.rutland@....com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf/smmuv3: add a check of devm_add_action in
 smmu_pmu_setup_msi

On Mon, Feb 27, 2023 at 11:25:57AM +0800, void0red wrote:
> From: Kang Chen <void0red@...il.com>
> 
> devm_add_action may fails, add a warning when it happens.
> 
> Signed-off-by: Kang Chen <void0red@...il.com>
> ---
>  drivers/perf/arm_smmuv3_pmu.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c
> index 25a269d43..307bac904 100644
> --- a/drivers/perf/arm_smmuv3_pmu.c
> +++ b/drivers/perf/arm_smmuv3_pmu.c
> @@ -724,7 +724,11 @@ static void smmu_pmu_setup_msi(struct smmu_pmu *pmu)
>  	pmu->irq = msi_get_virq(dev, 0);
>  
>  	/* Add callback to free MSIs on teardown */
> -	devm_add_action(dev, smmu_pmu_free_msis, dev);
> +	ret = devm_add_action(dev, smmu_pmu_free_msis, dev);
> +	if (ret) {
> +		dev_warn(dev, "failed to add callback to free MSIs on teardown\n");
> +		return;
> +	}

I appreciate that you're following the existing error handling in this
function, but I don't think this message is especially helpful. We'd be
better off propagating the error and failing the probe in this case, I
reckon.

Will