Re: [PATCH] drm/i915: Add missing check and destroy for alloc_workqueue

[Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>]

On Fri, Jan 06, 2023 at 05:09:34PM +0800, Jiasheng Jiang wrote:
> Add checks for the return value of alloc_workqueue and
> alloc_ordered_workqueue as they may return NULL pointer and cause NULL
> pointer dereference.
> Moreover, destroy them when fails later in order to avoid memory leak.
> Because in `drivers/gpu/drm/i915/i915_driver.c`, if
> intel_modeset_init_noirq fails, its workqueues will not be destroyed.
> 
> Fixes: c26a058680dc ("drm/i915: Use a high priority wq for nonblocking plane updates")
> Fixes: 757fffcfdffb ("drm/i915: Put all non-blocking modesets onto an ordered wq")
> Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>

Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>

>  drivers/gpu/drm/i915/display/intel_display.c | 21 ++++++++++++++++----
>  1 file changed, 17 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
> index 6c2686ecb62a..58f6840d6bd8 100644
> --- a/drivers/gpu/drm/i915/display/intel_display.c
> +++ b/drivers/gpu/drm/i915/display/intel_display.c
> @@ -8655,26 +8655,35 @@ int intel_modeset_init_noirq(struct drm_i915_private *i915)
>  	intel_dmc_ucode_init(i915);
>  
>  	i915->display.wq.modeset = alloc_ordered_workqueue("i915_modeset", 0);
> +	if (!i915->display.wq.modeset) {
> +		ret = -ENOMEM;
> +		goto cleanup_vga_client_pw_domain_dmc;
> +	}
> +
>  	i915->display.wq.flip = alloc_workqueue("i915_flip", WQ_HIGHPRI |
>  						WQ_UNBOUND, WQ_UNBOUND_MAX_ACTIVE);
> +	if (!i915->display.wq.flip) {
> +		ret = -ENOMEM;
> +		goto cleanup_modeset;
> +	}
>  
>  	intel_mode_config_init(i915);
>  
>  	ret = intel_cdclk_init(i915);
>  	if (ret)
> -		goto cleanup_vga_client_pw_domain_dmc;
> +		goto cleanup_flip;
>  
>  	ret = intel_color_init(i915);
>  	if (ret)
> -		goto cleanup_vga_client_pw_domain_dmc;
> +		goto cleanup_flip;
>  
>  	ret = intel_dbuf_init(i915);
>  	if (ret)
> -		goto cleanup_vga_client_pw_domain_dmc;
> +		goto cleanup_flip;
>  
>  	ret = intel_bw_init(i915);
>  	if (ret)
> -		goto cleanup_vga_client_pw_domain_dmc;
> +		goto cleanup_flip;
>  
>  	init_llist_head(&i915->display.atomic_helper.free_list);
>  	INIT_WORK(&i915->display.atomic_helper.free_work,
> @@ -8686,6 +8695,10 @@ int intel_modeset_init_noirq(struct drm_i915_private *i915)
>  
>  	return 0;
>  
> +cleanup_flip:
> +	destroy_workqueue(i915->display.wq.flip);
> +cleanup_modeset:
> +	destroy_workqueue(i915->display.wq.modeset);
>  cleanup_vga_client_pw_domain_dmc:
>  	intel_dmc_ucode_fini(i915);
>  	intel_power_domains_driver_remove(i915);
> -- 
> 2.25.1
>