Commit ee8d07cd authored by Yang Wang's avatar Yang Wang Committed by Alex Deucher
Browse files

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: 6ee27ee2 ("drm/amd/pm: avoid duplicate powergate/ungate setting")
Signed-off-by: default avatarYang Wang <kevinyang.wang@amd.com>
Reviewed-by: default avatarKenneth Feng <kenneth.feng@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 7a3fbdfd)
parent 8b1ecc93

drivers/gpu/drm/amd/pm/amdgpu_dpm.c

+4 −3
Original line number Diff line number Diff line
@@ -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;