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Subject: Re: [PATCH 1/2] staging: android: ion: Avoid NULL point in error path
To:     Yisheng Xie <xieyisheng1@huawei.com>, gregkh@linuxfoundation.org
Cc:     sumit.semwal@linaro.org, devel@driverdev.osuosl.org,
        linux-kernel@vger.kernel.org
References: <1517488447-41252-1-git-send-email-xieyisheng1@huawei.com>
From:   Laura Abbott <labbott@redhat.com>
Message-ID: <b5b6c497-94c8-16e8-a223-6c0e985a9acc@redhat.com>
Date:   Tue, 6 Feb 2018 14:59:49 -0800
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On 02/01/2018 04:34 AM, Yisheng Xie wrote:
> If we failed to create debugfs for ion at ion_device_create, the
> debug_root of ion_device will be NULL, and then when try to create debug
> file for shrinker of heap it will be create on the top of debugfs. If we
> also failed to create this the debug file, it call dentry_path to found
> the path of debug_root, then a NULL point will occur.
> 
> Fix this by avoiding call dentry_path, but show the debug name only when
> failed to create debug file for shrinker.
> 

Acked-by: Laura Abbott <labbott@redhat.com>

> Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
> ---
>   drivers/staging/android/ion/ion.c | 10 +++-------
>   1 file changed, 3 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c
> index f480885..3e41644 100644
> --- a/drivers/staging/android/ion/ion.c
> +++ b/drivers/staging/android/ion/ion.c
> @@ -570,13 +570,9 @@ void ion_device_add_heap(struct ion_heap *heap)
>   		debug_file = debugfs_create_file(
>   			debug_name, 0644, dev->debug_root, heap,
>   			&debug_shrink_fops);
> -		if (!debug_file) {
> -			char buf[256], *path;
> -
> -			path = dentry_path(dev->debug_root, buf, 256);
> -			pr_err("Failed to create heap shrinker debugfs at %s/%s\n",
> -			       path, debug_name);
> -		}
> +		if (!debug_file)
> +			pr_err("Failed to create ion heap shrinker debugfs at %s\n",
> +			       debug_name);
>   	}
>   
>   	dev->heap_cnt++;
>