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Subject: Re: [PATCH v2 4/9] staging: android: ion: Avoid NULL point in error
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To:     Greg KH <gregkh@linuxfoundation.org>
References: <1518432194-41536-1-git-send-email-xieyisheng1@huawei.com>
 <1518432194-41536-5-git-send-email-xieyisheng1@huawei.com>
 <20180216162732.GA18688@kroah.com>
CC:     <labbott@redhat.com>, <sumit.semwal@linaro.org>,
        <devel@driverdev.osuosl.org>, <linux-kernel@vger.kernel.org>
From:   Yisheng Xie <xieyisheng1@huawei.com>
Message-ID: <844e0fa1-cd03-8e2e-4a3e-6021a79610b4@huawei.com>
Date:   Thu, 22 Feb 2018 16:59:27 +0800
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Hi Greg,

Sorry for late responds for I was on vacation.

On 2018/2/17 0:27, Greg KH wrote:
> On Mon, Feb 12, 2018 at 06:43:09PM +0800, 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 57e0d80..4b69372 100644
>> --- a/drivers/staging/android/ion/ion.c
>> +++ b/drivers/staging/android/ion/ion.c
>> @@ -564,13 +564,9 @@ 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);
> 
> Really we can just remove this, there's no need to check the return
> value of this debugfs call at all, it doesn't matter.

Right, and I found that you have already patched this patch into next, should I send
another version for the two patches your commented, or just send fix patches to fold?

Thanks
Yisheng
> 
> thanks,
> 
> greg k-h
> 
> .
>