[BUG] gpu: drm: amdgpu: Possible sleep-in-atomic-context bugs in amdgpu_uvd_ring_begin_use()

[Jia-Ju Bai]

Thanks for your reply.

On 2018/9/15 17:01, Koenig, Christian wrote:
> Sorry to say that but your analysis tool is buggy.
>
> The proposed call paths will never trigger.

Could you please explain which piece of the call path is incorrect?
I am not very sure of my function pointer analysis.
Does amdgpu_ring_alloc() never calls amdgpu_uvd_ring_begin_use()?

Thanks in advance.


Best wishes,
Jia-Ju Bai

>
> Regards,
> Christian.
>
> Am 15.09.2018 10:59 schrieb Jia-Ju Bai <baijiaju1990 at gmail.com>:
> The driver may sleep with holding a spinlock.
> The function call paths (from bottom to top) in Linux-4.17 are:
>
> [FUNC] mutex_lock_nested
> drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c, 1477:
>      mutex_lock_nested in amdgpu_dpm_enable_uvd
> drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c, 1154:
>      amdgpu_dpm_enable_uvd in amdgpu_uvd_ring_begin_use
> drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c, 80:
>      [FUNC_PTR]amdgpu_uvd_ring_begin_use in amdgpu_ring_alloc
> drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c, 199:
>      amdgpu_ring_alloc in amdgpu_virt_kiq_wreg
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c, 207:
>      amdgpu_virt_kiq_wreg in amdgpu_mm_wreg
> drivers/gpu/drm/amd/amdgpu/vi.c, 207:
>      amdgpu_mm_wreg in vi_gc_cac_rreg
> drivers/gpu/drm/amd/amdgpu/vi.c, 206:
>      _raw_spin_lock_irqsave in vi_gc_cac_rreg
>
> [FUNC] mutex_lock_nested
> drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c, 1477:
>      mutex_lock_nested in amdgpu_dpm_enable_uvd
> drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c, 1154:
>      amdgpu_dpm_enable_uvd in amdgpu_uvd_ring_begin_use
> drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c, 80:
>      [FUNC_PTR]amdgpu_uvd_ring_begin_use in amdgpu_ring_alloc
> drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c, 199:
>      amdgpu_ring_alloc in amdgpu_virt_kiq_wreg
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c, 207:
>      amdgpu_virt_kiq_wreg in amdgpu_mm_wreg
> drivers/gpu/drm/amd/amdgpu/soc15.c, 106:
>      amdgpu_mm_wreg in soc15_pcie_rreg
> drivers/gpu/drm/amd/amdgpu/soc15.c, 105:
>      _raw_spin_lock_irqsave in soc15_pcie_rreg
>
> [FUNC] mutex_lock_nested
> drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c, 1477:
>      mutex_lock_nested in amdgpu_dpm_enable_uvd
> drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c, 1154:
>      amdgpu_dpm_enable_uvd in amdgpu_uvd_ring_begin_use
> drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c, 80:
>      [FUNC_PTR]amdgpu_uvd_ring_begin_use in amdgpu_ring_alloc
> drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c, 199:
>      amdgpu_ring_alloc in amdgpu_virt_kiq_wreg
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c, 207:
>      amdgpu_virt_kiq_wreg in amdgpu_mm_wreg
> drivers/gpu/drm/amd/amdgpu/cik.c, 139:
>      amdgpu_mm_wreg in cik_uvd_ctx_wreg
> drivers/gpu/drm/amd/amdgpu/cik.c, 138:
>      _raw_spin_lock_irqsave in cik_uvd_ctx_wreg
>
> [FUNC] mutex_lock_nested
> drivers/gpu/drm/amd/amdgpu/amdgpu_pm.c, 1477:
>      mutex_lock_nested in amdgpu_dpm_enable_uvd
> drivers/gpu/drm/amd/amdgpu/amdgpu_uvd.c, 1154:
>      amdgpu_dpm_enable_uvd in amdgpu_uvd_ring_begin_use
> drivers/gpu/drm/amd/amdgpu/amdgpu_ring.c, 80:
>      [FUNC_PTR]amdgpu_uvd_ring_begin_use in amdgpu_ring_alloc
> drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c, 199:
>      amdgpu_ring_alloc in amdgpu_virt_kiq_wreg
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c, 207:
>      amdgpu_virt_kiq_wreg in amdgpu_mm_wreg
> drivers/gpu/drm/amd/amdgpu/dce_v6_0.c, 126:
>      amdgpu_mm_wreg in dce_v6_0_audio_endpt_rreg
> drivers/gpu/drm/amd/amdgpu/dce_v6_0.c, 125:
>      _raw_spin_lock_irqsave in dce_v6_0_audio_endpt_rreg
>
> Note that [FUNC_PTR] means a function pointer call is used.
>
> These bugs are found by my static analysis tool DSAC.
>
>
> Best wishes,
> Jia-Ju Bai

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