linux-kernel - Re: [PATCH] drivers/perf: xgene_pmu: Fix uninitialized resource struct

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Message-ID: <20200907135026.GC12551@willie-the-truck>
Date:   Mon, 7 Sep 2020 14:50:26 +0100
From:   Will Deacon <will@...nel.org>
To:     Mark Salter <msalter@...hat.com>
Cc:     Mark Rutland <mark.rutland@....com>,
        Khuong Dinh <khuong@...amperecomputing.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers/perf: xgene_pmu: Fix uninitialized resource
 struct

On Wed, Sep 02, 2020 at 02:27:29PM -0400, Mark Salter wrote:
> diff --git a/drivers/perf/xgene_pmu.c b/drivers/perf/xgene_pmu.c
> index edac28cd25dd..fdbbd0804b92 100644
> --- a/drivers/perf/xgene_pmu.c
> +++ b/drivers/perf/xgene_pmu.c
> @@ -1483,6 +1483,7 @@ xgene_pmu_dev_ctx *acpi_get_pmu_hw_inf(struct xgene_pmu *xgene_pmu,
>  		return NULL;
>  
>  	INIT_LIST_HEAD(&resource_list);
> +	memset(&res, 0, sizeof(res));
>  	rc = acpi_dev_get_resources(adev, &resource_list,
>  				    acpi_pmu_dev_add_resource, &res);
>  	acpi_dev_free_resource_list(&resource_list);

Hmm, to be honest, I'm not sure we should be calling devm_ioremap_resource()
at all here. The resource is clearly bogus, even with this change: the name
and the resource hierarchy pointers will all be NULL. I think it would be
better to follow the TX2 PMU driver (drivers/perf/thunderx2_pmu.c) which
appears to assign the resource directly in tx2_uncore_pmu_init_dev().

Is there a reason we can't do that?

Will