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Message-ID: <d0753768-874e-6f41-550d-c10dfc6f9c5b@nfschina.com>
Date:   Tue, 10 Oct 2023 16:19:32 +0800
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Subject: Re: [PATCH] fs/9p/xattr.c: avoid format-overflow warning
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To:     Dan Carpenter <dan.carpenter@linaro.org>
Cc:     ericvh@kernel.org, lucho@ionkov.net, asmadeus@codewreck.org,
        linux_oss@crudebyte.com, v9fs@lists.linux.dev,
        linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
From:   Su Hui <suhui@nfschina.com>
In-Reply-To: <56aa4f09-8f61-48f3-9836-687bf852b03a@kadam.mountain>
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On 2023/10/10 15:51, Dan Carpenter wrote:
> On Sun, Oct 08, 2023 at 02:01:39PM +0800, Su Hui wrote:
>> with gcc and W=1 option, there's a warning like this:
>>
>> In file included from fs/9p/xattr.c:12:
>> In function ‘v9fs_xattr_get’,
>>      inlined from ‘v9fs_listxattr’ at fs/9p/xattr.c:142:9:
>> include/net/9p/9p.h:55:2: error: ‘%s’ directive argument is null
>> [-Werror=format-overflow=]
>>     55 |  _p9_debug(level, __func__, fmt, ##__VA_ARGS__)
>>        |  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>
>> use "" replace NULL to silence this warning.
>>
>> Signed-off-by: Su Hui <suhui@nfschina.com>
>> ---
>>   fs/9p/xattr.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/fs/9p/xattr.c b/fs/9p/xattr.c
>> index e00cf8109b3f..d995ee080835 100644
>> --- a/fs/9p/xattr.c
>> +++ b/fs/9p/xattr.c
>> @@ -139,7 +139,7 @@ int v9fs_fid_xattr_set(struct p9_fid *fid, const char *name,
>>   
>>   ssize_t v9fs_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size)
>>   {
>> -	return v9fs_xattr_get(dentry, NULL, buffer, buffer_size);
>> +	return v9fs_xattr_get(dentry, "", buffer, buffer_size);
> I'm pretty uncomfortable with this patch...  This code is 13 years old
> so it can't be too huge of a problem.  We're doing this for the printks,
> but now they're going to look weird first of all.
>
> Old: "file = (null)"
> New: "file = "
Agreed, this looks  really weird and the patch is just for avoiding 
gcc's warning.
Sorry for the noise.

Su Hui

>
> But also this must have some other effects on runtime right?
>
> regards,
> dan carpenter
>