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SubjectRe: [PATCH] drm/msm/disp/dpu1: avoid clearing hw interrupts if hw_intr is null during drm uninit
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On 27/04/2022 00:50, Stephen Boyd wrote:
> Quoting Vinod Polimera (2022-04-25 23:02:11)
>> Avoid clearing irqs and derefernce hw_intr when hw_intr is null.
>
> Presumably this is only the case when the display driver doesn't fully
> probe and something probe defers? Can you clarify how this situation
> happens?
>
>>
>> BUG: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
>>
>> Call trace:
>> dpu_core_irq_uninstall+0x50/0xb0
>> dpu_irq_uninstall+0x18/0x24
>> msm_drm_uninit+0xd8/0x16c
>> msm_drm_bind+0x580/0x5fc
>> try_to_bring_up_master+0x168/0x1c0
>> __component_add+0xb4/0x178
>> component_add+0x1c/0x28
>> dp_display_probe+0x38c/0x400
>> platform_probe+0xb0/0xd0
>> really_probe+0xcc/0x2c8
>> __driver_probe_device+0xbc/0xe8
>> driver_probe_device+0x48/0xf0
>> __device_attach_driver+0xa0/0xc8
>> bus_for_each_drv+0x8c/0xd8
>> __device_attach+0xc4/0x150
>> device_initial_probe+0x1c/0x28
>>
>> Fixes: a73033619ea ("drm/msm/dpu: squash dpu_core_irq into dpu_hw_interrupts")
>
> The fixes tag looks odd. In dpu_core_irq_uninstall() at that commit it
> is dealing with 'irq_obj' which isn't a pointer. After commit
> f25f656608e3 ("drm/msm/dpu: merge struct dpu_irq into struct
> dpu_hw_intr") dpu_core_irq_uninstall() starts using 'hw_intr' which is
> allocated on the heap. If we backported this patch to a place that had
> a73033619ea without f25f656608e3 it wouldn't make any sense.

I'd agree here. The following tag would be correct:

Fixes: f25f656608e3 ("drm/msm/dpu: merge struct dpu_irq into struct
dpu_hw_intr")


>
>> Signed-off-by: Vinod Polimera <quic_vpolimer@quicinc.com>
>> ---
>> drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> index c515b7c..ab28577 100644
>> --- a/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> +++ b/drivers/gpu/drm/msm/disp/dpu1/dpu_hw_interrupts.c
>> @@ -599,6 +599,9 @@ void dpu_core_irq_uninstall(struct dpu_kms *dpu_kms)
>> {
>> int i;
>>
>> + if (!dpu_kms->hw_intr)
>> + return;
>> +
>> pm_runtime_get_sync(&dpu_kms->pdev->dev);
>> for (i = 0; i < dpu_kms->hw_intr->total_irqs; i++)


--
With best wishes
Dmitry

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