linux-kernel - Re: [PATCH -next] drm: Fix error handling in drm_legacy

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Date:   Mon, 7 Jan 2019 11:26:55 +0100
From:   Daniel Vetter <daniel@...ll.ch>
To:     YueHaibing <yuehaibing@...wei.com>
Cc:     maarten.lankhorst@...ux.intel.com, maxime.ripard@...tlin.com,
        sean@...rly.run, airlied@...ux.ie, daniel@...ll.ch,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH -next] drm: Fix error handling in drm_legacy_addctx

On Sat, Dec 29, 2018 at 10:49:07AM +0800, YueHaibing wrote:
> 'ctx->handle' is unsigned, it never less than zero.
> This patch use int 'tmp_handle' to handle the err condition.
> 
> Fixes: 62968144e673 ("drm: convert drm context code to use Linux idr")
> Signed-off-by: YueHaibing <yuehaibing@...wei.com>

Queue for 5.1 (since this is essentially dead legacy code there's no
really a need to backport this).
-Daniel

> ---
>  drivers/gpu/drm/drm_context.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_context.c b/drivers/gpu/drm/drm_context.c
> index 506663c..8e73fab 100644
> --- a/drivers/gpu/drm/drm_context.c
> +++ b/drivers/gpu/drm/drm_context.c
> @@ -361,23 +361,26 @@ int drm_legacy_addctx(struct drm_device *dev, void *data,
>  {
>  	struct drm_ctx_list *ctx_entry;
>  	struct drm_ctx *ctx = data;
> +	int tmp_handle;
>  
>  	if (!drm_core_check_feature(dev, DRIVER_KMS_LEGACY_CONTEXT) &&
>  	    !drm_core_check_feature(dev, DRIVER_LEGACY))
>  		return -EOPNOTSUPP;
>  
> -	ctx->handle = drm_legacy_ctxbitmap_next(dev);
> -	if (ctx->handle == DRM_KERNEL_CONTEXT) {
> +	tmp_handle = drm_legacy_ctxbitmap_next(dev);
> +	if (tmp_handle == DRM_KERNEL_CONTEXT) {
>  		/* Skip kernel's context and get a new one. */
> -		ctx->handle = drm_legacy_ctxbitmap_next(dev);
> +		tmp_handle = drm_legacy_ctxbitmap_next(dev);
>  	}
> -	DRM_DEBUG("%d\n", ctx->handle);
> -	if (ctx->handle < 0) {
> +	DRM_DEBUG("%d\n", tmp_handle);
> +	if (tmp_handle < 0) {
>  		DRM_DEBUG("Not enough free contexts.\n");
>  		/* Should this return -EBUSY instead? */
> -		return -ENOMEM;
> +		return tmp_handle;
>  	}
>  
> +	ctx->handle = tmp_handle;
> +
>  	ctx_entry = kmalloc(sizeof(*ctx_entry), GFP_KERNEL);
>  	if (!ctx_entry) {
>  		DRM_DEBUG("out of memory\n");
> -- 
> 2.7.0
> 
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch