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drm/amd/pm: fix race in power state check before mutex lock 

The power state check in amdgpu_dpm_set_powergating_by_smu() is done
before acquiring the pm mutex, leading to a race condition where:
1. Thread A checks state and thinks no change is needed
2. Thread B acquires mutex and modifies the state
3. Thread A returns without updating state, causing inconsistency

Fix this by moving the mutex lock before the power state check,
ensuring atomicity of the state check and modification.

Fixes: 6ee27ee27b ("drm/amd/pm: avoid duplicate powergate/ungate setting")
Signed-off-by: Yang Wang <kevinyang.wang@amd.com>
Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Yang Wang 2026-01-27 11:07:07 +08:00 committed by Alex Deucher
parent 37e6349e93
commit 7a3fbdfd19
1 changed files with 4 additions and 3 deletions
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7
drivers/gpu/drm/amd/pm/amdgpu_dpm.c
View File

@ -80,15 +80,15 @@ int amdgpu_dpm_set_powergating_by_smu(struct amdgpu_device *adev,
enum ip_power_state pwr_state = gate ? POWER_STATE_OFF : POWER_STATE_ON;
bool is_vcn = block_type == AMD_IP_BLOCK_TYPE_VCN;
mutex_lock(&adev->pm.mutex);
if (atomic_read(&adev->pm.pwr_state[block_type]) == pwr_state &&
(!is_vcn || adev->vcn.num_vcn_inst == 1)) {
dev_dbg(adev->dev, "IP block%d already in the target %s state!",
block_type, gate ? "gate" : "ungate");
return 0;
goto out_unlock;
}
mutex_lock(&adev->pm.mutex);
switch (block_type) {
case AMD_IP_BLOCK_TYPE_UVD:
case AMD_IP_BLOCK_TYPE_VCE:
@ -115,6 +115,7 @@ int amdgpu_dpm_set_powergating_by_smu(struct amdgpu_device *adev,
if (!ret)
atomic_set(&adev->pm.pwr_state[block_type], pwr_state);
out_unlock:
mutex_unlock(&adev->pm.mutex);
return ret;