Re: [PATCH] iommu/arm: Cleanup resources in case of probe error path

[Marek Szyprowski]

On 30.06.2021 14:59, Will Deacon wrote:
> On Wed, Jun 30, 2021 at 02:48:15PM +0200, Marek Szyprowski wrote:
>> On 08.06.2021 18:45, Amey Narkhede wrote:
>>> If device registration fails, remove sysfs attribute
>>> and if setting bus callbacks fails, unregister the device
>>> and cleanup the sysfs attribute.
>>>
>>> Signed-off-by: Amey Narkhede <ameynarkhede03@xxxxxxxxx>
>> This patch landed in linux-next some time ago as commit 249c9dc6aa0d
>> ("iommu/arm: Cleanup resources in case of probe error path"). After
>> bisecting and some manual searching I finally found that it is
>> responsible for breaking s2idle on DragonBoard 410c. Here is the log
>> (captured with no_console_suspend):
>>
>> # time rtcwake -s10 -mmem
>> rtcwake: wakeup from "mem" using /dev/rtc0 at Thu Jan  1 00:02:13 1970
>> PM: suspend entry (s2idle)
>> Filesystems sync: 0.002 seconds
>> Freezing user space processes ... (elapsed 0.006 seconds) done.
>> OOM killer disabled.
>> Freezing remaining freezable tasks ... (elapsed 0.004 seconds) done.
>> Unable to handle kernel NULL pointer dereference at virtual address
>> 0000000000000070
>> Mem abort info:
>>     ESR = 0x96000006
>>     EC = 0x25: DABT (current EL), IL = 32 bits
>>     SET = 0, FnV = 0
>>     EA = 0, S1PTW = 0
>>     FSC = 0x06: level 2 translation fault
>> Data abort info:
>>     ISV = 0, ISS = 0x00000006
>>     CM = 0, WnR = 0
>> user pgtable: 4k pages, 48-bit VAs, pgdp=000000008ad08000
>> [0000000000000070] pgd=0800000085c3c003, p4d=0800000085c3c003,
>> pud=0800000088dcf003, pmd=0000000000000000
>> Internal error: Oops: 96000006 [#1] PREEMPT SMP
>> Modules linked in: bluetooth ecdh_generic ecc rfkill ipv6 ax88796b
>> venus_enc venus_dec videobuf2_dma_contig asix crct10dif_ce adv7511
>> snd_soc_msm8916_analog qcom_spmi_temp_alarm rtc_pm8xxx qcom_pon
>> qcom_camss qcom_spmi_vadc videobuf2_dma_sg qcom_vadc_common msm
>> venus_core v4l2_fwnode v4l2_async snd_soc_msm8916_digital
>> videobuf2_memops snd_soc_lpass_apq8016 snd_soc_lpass_cpu v4l2_mem2mem
>> snd_soc_lpass_platform snd_soc_apq8016_sbc videobuf2_v4l2
>> snd_soc_qcom_common qcom_rng videobuf2_common i2c_qcom_cci qnoc_msm8916
>> videodev mc icc_smd_rpm mdt_loader socinfo display_connector rmtfs_mem
>> CPU: 1 PID: 1522 Comm: rtcwake Not tainted 5.13.0-next-20210629 #3592
>> Hardware name: Qualcomm Technologies, Inc. APQ 8016 SBC (DT)
>> pstate: 80000005 (Nzcv daif -PAN -UAO -TCO BTYPE=--)
>> pc : msm_runtime_suspend+0x1c/0x60 [msm]
>> lr : msm_pm_suspend+0x18/0x38 [msm]
>> ...
>> Call trace:
>>    msm_runtime_suspend+0x1c/0x60 [msm]
>>    msm_pm_suspend+0x18/0x38 [msm]
>>    dpm_run_callback+0x84/0x378
> I wonder if we're missing a pm_runtime_disable() call on the failure path?
> i.e. something like the diff below...

I've checked and it doesn't fix anything.

> Will
>
> --->8
>
> diff --git a/drivers/iommu/arm/arm-smmu/qcom_iommu.c b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> index 25ed444ff94d..ce8f354755d0 100644
> --- a/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> +++ b/drivers/iommu/arm/arm-smmu/qcom_iommu.c
> @@ -836,14 +836,14 @@ static int qcom_iommu_device_probe(struct platform_device *pdev)
>          ret = devm_of_platform_populate(dev);
>          if (ret) {
>                  dev_err(dev, "Failed to populate iommu contexts\n");
> -               return ret;
> +               goto err_pm_disable;
>          }
>   
>          ret = iommu_device_sysfs_add(&qcom_iommu->iommu, dev, NULL,
>                                       dev_name(dev));
>          if (ret) {
>                  dev_err(dev, "Failed to register iommu in sysfs\n");
> -               return ret;
> +               goto err_pm_disable;
>          }
>   
>          ret = iommu_device_register(&qcom_iommu->iommu, &qcom_iommu_ops, dev);
> @@ -869,6 +869,9 @@ static int qcom_iommu_device_probe(struct platform_device *pdev)
>   
>   err_sysfs_remove:
>          iommu_device_sysfs_remove(&qcom_iommu->iommu);
> +
> +err_pm_disable:
> +       pm_runtime_disable(dev);
>          return ret;
>   }
>
Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland