On Thu, May 14, 2026 at 3:27 AM Sunil Khatri <[email protected]> wrote: > > In amdgpu_seq64_alloc there is a possibility that two difference cores > from two separate NODES can try to and could get the same free slot. > So this fixes that race here using atomic test_and_set clear operations. > > Signed-off-by: Sunil Khatri <[email protected]>
Reviewed-by: Alex Deucher <[email protected]> > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c | 13 ++++++++----- > 1 file changed, 8 insertions(+), 5 deletions(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c > b/drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c > index a0b479d5fff1..f4be19223588 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c > @@ -175,11 +175,14 @@ int amdgpu_seq64_alloc(struct amdgpu_device *adev, u64 > *va, > { > unsigned long bit_pos; > > - bit_pos = find_first_zero_bit(adev->seq64.used, adev->seq64.num_sem); > - if (bit_pos >= adev->seq64.num_sem) > - return -ENOSPC; > + for (;;) { > + bit_pos = find_first_zero_bit(adev->seq64.used, > adev->seq64.num_sem); > + if (bit_pos >= adev->seq64.num_sem) > + return -ENOSPC; > > - __set_bit(bit_pos, adev->seq64.used); > + if (!test_and_set_bit(bit_pos, adev->seq64.used)) > + break; > + } > > *va = bit_pos * sizeof(u64) + amdgpu_seq64_get_va_base(adev); > > @@ -205,7 +208,7 @@ void amdgpu_seq64_free(struct amdgpu_device *adev, u64 va) > > bit_pos = (va - amdgpu_seq64_get_va_base(adev)) / sizeof(u64); > if (bit_pos < adev->seq64.num_sem) > - __clear_bit(bit_pos, adev->seq64.used); > + clear_bit(bit_pos, adev->seq64.used); > } > > /** > -- > 2.34.1 >
