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| author | Sunil Khatri <sunil.khatri@amd.com> | 2026-05-14 10:01:00 +0300 |
|---|---|---|
| committer | Alex Deucher <alexander.deucher@amd.com> | 2026-05-19 19:11:34 +0300 |
| commit | 0978406224d21bd35f9230a25534849ec06bf74c (patch) | |
| tree | c2046f6dc4a221b9cf79d74cbe8468e15ddd881d /drivers/gpu | |
| parent | a1d4b228e3dc5134c4bd06e55e81dbb604c8cadb (diff) | |
| download | linux-0978406224d21bd35f9230a25534849ec06bf74c.tar.xz | |
drm/amdgpu: use atomic operation to achieve lockless serialization
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 <sunil.khatri@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 4d50a14d346141e03a7c3905e496d91e048bc30c)
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/amd/amdgpu/amdgpu_seq64.c | 13 |
1 files 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); } /** |