Re: [PATCH 2/3] drivers/perf: arm_pmu: Defer the setting of __oprofile_cpu_pmu

From: Will Deacon
Date: Tue May 31 2016 - 12:28:32 EST


On Tue, May 31, 2016 at 12:41:22PM +0100, Julien Grall wrote:
> The global variable __oprofile_cpu_pmu is set before the PMU is fully
> initialized. If an error occurs before the end of the initialization,
> the PMU will be freed and the variable will contain an invalid pointer.
>
> This will result in a kernel crash when perf will be used.
>
> Fix it by moving the setting of __oprofile_cpu_pmu when the PMU is fully
> initialized (i.e when it is no longer possible to fail).
>
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> Acked-by: Mark Rutland <mark.rutland@xxxxxxx>
> ---
> drivers/perf/arm_pmu.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)

Should this one go to -stable too?

Will

> diff --git a/drivers/perf/arm_pmu.c b/drivers/perf/arm_pmu.c
> index 6401f0c..95614d2 100644
> --- a/drivers/perf/arm_pmu.c
> +++ b/drivers/perf/arm_pmu.c
> @@ -992,9 +992,6 @@ int arm_pmu_device_probe(struct platform_device *pdev,
>
> armpmu_init(pmu);
>
> - if (!__oprofile_cpu_pmu)
> - __oprofile_cpu_pmu = pmu;
> -
> pmu->plat_device = pdev;
>
> if (node && (of_id = of_match_node(of_table, pdev->dev.of_node))) {
> @@ -1030,6 +1027,9 @@ int arm_pmu_device_probe(struct platform_device *pdev,
> if (ret)
> goto out_destroy;
>
> + if (!__oprofile_cpu_pmu)
> + __oprofile_cpu_pmu = pmu;
> +
> pr_info("enabled with %s PMU driver, %d counters available\n",
> pmu->name, pmu->num_events);
>
> --
> 1.9.1
>