[igt-dev] [PATCH i-g-t] lib: Fix device lists not cleaned up sufficiently before rescan

[Zbigniew Kempczyński]

On Fri, Mar 20, 2020 at 04:36:23PM +0100, Janusz Krzysztofik wrote:
> Some effort is already taken to clean up previous content of device
> lists before forced device rescan is performed but it is not
> sufficient.  An attempt to use forced device rescan in a test results
> in that test crashing or spinning until being killed by OOM killer.
> Fix it.
> 
> Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik at linux.intel.com>
> ---
>  lib/igt_device_scan.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
> 
> diff --git a/lib/igt_device_scan.c b/lib/igt_device_scan.c
> index b3f79c81e..db4da30d3 100644
> --- a/lib/igt_device_scan.c
> +++ b/lib/igt_device_scan.c
> @@ -353,14 +353,11 @@ static void set_vendor_device(struct igt_device *dev)
>  	dev->device = strndup(pci_id + 5, 4);
>  }
>  
> -/* Allocate arrays for keeping scanned devices */
> +/* Initialize lists for keeping scanned devices */
>  static bool prepare_scan(void)
>  {
> -	if (igt_devs.all.prev == NULL || igt_devs.all.next == NULL)
> -		IGT_INIT_LIST_HEAD(&igt_devs.all);
> -
> -	if (igt_devs.filtered.prev == NULL || igt_devs.filtered.next == NULL)
> -		IGT_INIT_LIST_HEAD(&igt_devs.filtered);
> +	IGT_INIT_LIST_HEAD(&igt_devs.all);
> +	IGT_INIT_LIST_HEAD(&igt_devs.filtered);

I think above change according to the change below is not required. 

>  
>  	return true;
>  }
> @@ -595,8 +592,15 @@ void igt_devices_scan(bool force)
>  {
>  	if (force && igt_devs.devs_scanned) {
>  		struct igt_device *dev, *tmp;
> +
> +		igt_list_for_each_entry_safe(dev, tmp, &igt_devs.filtered,
> +					     link) {
> +			igt_list_del(&dev->link);
> +			free(dev);
> +		}
>  		igt_list_for_each_entry_safe(dev, tmp, &igt_devs.all, link) {
>  			igt_device_free(dev);
> +			igt_list_del(&dev->link);
>  			free(dev);
>  		}
>  
> -- 
> 2.21.1
>

Yes, that part is what we need to fix the leak. 

Reviewed-by: Zbigniew Kempczyński <zbigniew.kempczynski at intel.com>