Messages in this thread | | | Subject | Re: [PATCH] drivers/perf: Fix kernel panic when rmmod PMU modules during perf sampling | From | John Garry <> | Date | Thu, 16 Jul 2020 11:21:25 +0100 |
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On 16/07/2020 10:41, Will Deacon wrote: > On Thu, Jul 16, 2020 at 05:19:25PM +0800, Qi Liu wrote: >> Kernel panic will also happen when users try to unbind PMU drivers with >> device. This unbind issue could be solved by another patch latter. >> >> drivers/perf/arm_smmuv3_pmu.c | 1 + >> drivers/perf/fsl_imx8_ddr_perf.c | 1 + >> drivers/perf/hisilicon/hisi_uncore_ddrc_pmu.c | 1 + >> drivers/perf/hisilicon/hisi_uncore_hha_pmu.c | 1 + >> drivers/perf/hisilicon/hisi_uncore_l3c_pmu.c | 1 + >> 5 files changed, 5 insertions(+) >> >> diff --git a/drivers/perf/arm_smmuv3_pmu.c b/drivers/perf/arm_smmuv3_pmu.c >> index 48e28ef..90caba56 100644 >> --- a/drivers/perf/arm_smmuv3_pmu.c >> +++ b/drivers/perf/arm_smmuv3_pmu.c >> @@ -742,6 +742,7 @@ static int smmu_pmu_probe(struct platform_device *pdev) >> platform_set_drvdata(pdev, smmu_pmu); >> >> smmu_pmu->pmu = (struct pmu) { >> + .module = THIS_MODULE, > > I thought platform_driver_register() did this automatically? >
Isn't that something different? The perf framework knows nothing of the platform_device/driver really, and just knows the event_source device which it creates. And so we also need to tell the perf framework about the module backing this pmu.
I think some relevant code is perf_try_init_event() -> try_module_get(pmu->module).
Thanks, John
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