Re: [PATCH] fs/9p/xattr.c: avoid format-overflow warning

[Su Hui]

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@xxxxxxxxxxxx>
> > ---
> >   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