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

[Koenig, Christian]

amdgpu_ring_alloc() does call amdgpu_uvd_begin_use(), but never in the call chain you proposed.

Thinking about it I actually don't see a way a statically analysis could ever figure that out.

Christian.

Am 15.09.2018 11:05 schrieb Jia-Ju Bai <baijiaju1990 at gmail.com>:
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><mailto: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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