[PATCH] dma-buf: Release module reference on creation failure

[PATCH] dma-buf: Release module reference on creation failure

[Chris Wilson]

If we fail to create the anon file, we need to remember to release the
module reference on the owner.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
---
 drivers/dma-buf/dma-buf.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index 4a2c07ee6677..6f0f0b10a241 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -333,6 +333,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 	struct reservation_object *resv = exp_info->resv;
 	struct file *file;
 	size_t alloc_size = sizeof(struct dma_buf);
+	int ret;
 
 	if (!exp_info->resv)
 		alloc_size += sizeof(struct reservation_object);
@@ -356,8 +357,8 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 
 	dmabuf = kzalloc(alloc_size, GFP_KERNEL);
 	if (!dmabuf) {
-		module_put(exp_info->owner);
-		return ERR_PTR(-ENOMEM);
+		ret = -ENOMEM;
+		goto free_module;
 	}
 
 	dmabuf->priv = exp_info->priv;
@@ -378,8 +379,8 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 	file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf,
 					exp_info->flags);
 	if (IS_ERR(file)) {
-		kfree(dmabuf);
-		return ERR_CAST(file);
+		ret = PTR_ERR(file);
+		goto free_dmabuf;
 	}
 
 	file->f_mode |= FMODE_LSEEK;
@@ -393,6 +394,12 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
 	mutex_unlock(&db_list.lock);
 
 	return dmabuf;
+
+free_dmabuf:
+	kfree(dmabuf);
+free_module:
+	module_put(exp_info->owner);
+	return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(dma_buf_export);
 
-- 
2.8.0.rc3

Re: [Intel-gfx] [PATCH] dma-buf: Release module reference on creation failure

[Joonas Lahtinen]

On to, 2016-03-31 at 09:35 +0100, Chris Wilson wrote:
> If we fail to create the anon file, we need to remember to release the
> module reference on the owner.
> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Sumit Semwal <sumit.semwal@linaro.org>
> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
> Cc: linux-media@vger.kernel.org
> Cc: dri-devel@lists.freedesktop.org
> Cc: linaro-mm-sig@lists.linaro.org
> ---
>  drivers/dma-buf/dma-buf.c | 15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
> index 4a2c07ee6677..6f0f0b10a241 100644
> --- a/drivers/dma-buf/dma-buf.c
> +++ b/drivers/dma-buf/dma-buf.c
> @@ -333,6 +333,7 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
>  	struct reservation_object *resv = exp_info->resv;
>  	struct file *file;
>  	size_t alloc_size = sizeof(struct dma_buf);
> +	int ret;
>  
>  	if (!exp_info->resv)
>  		alloc_size += sizeof(struct reservation_object);
> @@ -356,8 +357,8 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
>  
>  	dmabuf = kzalloc(alloc_size, GFP_KERNEL);
>  	if (!dmabuf) {
> -		module_put(exp_info->owner);
> -		return ERR_PTR(-ENOMEM);
> +		ret = -ENOMEM;
> +		goto free_module;
>  	}
>  
>  	dmabuf->priv = exp_info->priv;
> @@ -378,8 +379,8 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
>  	file = anon_inode_getfile("dmabuf", &dma_buf_fops, dmabuf,
>  					exp_info->flags);
>  	if (IS_ERR(file)) {
> -		kfree(dmabuf);
> -		return ERR_CAST(file);
> +		ret = PTR_ERR(file);
> +		goto free_dmabuf;
>  	}
>  
>  	file->f_mode |= FMODE_LSEEK;
> @@ -393,6 +394,12 @@ struct dma_buf *dma_buf_export(const struct dma_buf_export_info *exp_info)
>  	mutex_unlock(&db_list.lock);
>  
>  	return dmabuf;
> +
> +free_dmabuf:
> +	kfree(dmabuf);
> +free_module:
> +	module_put(exp_info->owner);
> +	return ERR_PTR(ret);

Labels could really be err_dmabuf (/ out_dmabuf). That's more in line
with rest of the codebase and kernel coding style: 'An example of a
good name could be "out_buffer:" if the goto frees "buffer".'

"free_dmabuf" does sound to me like it could also be executed on the
normal execution path of the function.

Other than that,

Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>

>  }
>  EXPORT_SYMBOL_GPL(dma_buf_export);
>  
-- 
Joonas Lahtinen
Open Source Technology Center
Intel Corporation