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

[Jia-Ju Bai]

Sorry, I am still not clear why the call chain I proposed is incorrect...

I find a conditional in amdgpu_mm_wreg():

    if (!(acc_flags & AMDGPU_REGS_NO_KIQ) && amdgpu_sriov_runtime(adev))
        return amdgpu_virt_kiq_wreg(adev, reg, v);

Is amdgpu_virt_kiq_wreg() never called from WREG32() or RREG32()?


Best wishes,
Jia-Ju Bai


On 2018/9/15 17:10, Koenig, Christian wrote:

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 <baijiaju1...@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
        <baijiaju1...@gmail.com> <mailto:baijiaju1...@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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