[PATCH] add missing mutex lock to amdgpu_get_xgmi_hive()

[StDenis, Tom]

Self NAK this ... calling functions take the same lock....

We should remove the locks from the callers so this function is thread 
safe on its own...

Tom


On 2019-01-07 10:00 a.m., StDenis, Tom wrote:
> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c | 13 +++++++++++--
>   1 file changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> index 8a8bc60cb6b4..587a5f73ae8c 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c
> @@ -47,13 +47,20 @@ struct amdgpu_hive_info *amdgpu_get_xgmi_hive(struct amdgpu_device *adev)
>   
>   	if (!adev->gmc.xgmi.hive_id)
>   		return NULL;
> +
> +	mutex_lock(&xgmi_mutex);
> +
>   	for (i = 0 ; i < hive_count; ++i) {
>   		tmp = &xgmi_hives[i];
> -		if (tmp->hive_id == adev->gmc.xgmi.hive_id)
> +		if (tmp->hive_id == adev->gmc.xgmi.hive_id) {
> +			mutex_unlock(&xgmi_mutex);
>   			return tmp;
> +		}
>   	}
> -	if (i >= AMDGPU_MAX_XGMI_HIVE)
> +	if (i >= AMDGPU_MAX_XGMI_HIVE) {
> +		mutex_unlock(&xgmi_mutex);
>   		return NULL;
> +	}
>   
>   	/* initialize new hive if not exist */
>   	tmp = &xgmi_hives[hive_count++];
> @@ -61,6 +68,8 @@ struct amdgpu_hive_info *amdgpu_get_xgmi_hive(struct amdgpu_device *adev)
>   	INIT_LIST_HEAD(&tmp->device_list);
>   	mutex_init(&tmp->hive_lock);
>   
> +	mutex_unlock(&xgmi_mutex);
> +
>   	return tmp;
>   }
>   
>