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: 6ee27ee27ba8 ("drm/amd/pm: avoid duplicate powergate/ungate setting")
Signed-off-by: Yang Wang <[email protected]>
---
drivers/gpu/drm/amd/pm/amdgpu_dpm.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/pm/amdgpu_dpm.c
b/drivers/gpu/drm/amd/pm/amdgpu_dpm.c
index 4214f7314963..feadf604b474 100644
--- a/drivers/gpu/drm/amd/pm/amdgpu_dpm.c
+++ b/drivers/gpu/drm/amd/pm/amdgpu_dpm.c
@@ -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;
--
2.34.1
