linux-kernel - Re: [PATCH next] mm/mempolicy: Fix error code in sysfs_wi_node

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Message-ID: <aBRv6RmQf7vNZQMJ@stanley.mountain>
Date: Fri, 2 May 2025 10:10:33 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Honggyu Kim <honggyu.kim@...com>
Cc: Rakie Kim <rakie.kim@...com>, kernel_team@...ynix.com,
	Andrew Morton <akpm@...ux-foundation.org>,
	Dan Williams <dan.j.williams@...el.com>,
	Joshua Hahn <joshua.hahnjy@...il.com>,
	Gregory Price <gourry@...rry.net>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH next] mm/mempolicy: Fix error code in sysfs_wi_node_add()

On Fri, May 02, 2025 at 03:46:21PM +0900, Honggyu Kim wrote:
> Hi Dan,
> 
> On 4/23/2025 5:24 PM, Dan Carpenter wrote:
> > Return -EEXIST if the node already exists.  Don't return success.
> > 
> > Fixes: 1bf270ac1b0a ("mm/mempolicy: support memory hotplug in weighted interleave")
> > Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> > ---
> > Potentially returning success was intentional?  This is from static
> > analysis and I can't be totally sure.
> > 
> >   mm/mempolicy.c | 3 ++-
> >   1 file changed, 2 insertions(+), 1 deletion(-)
> > 
> > diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> > index f43951668c41..0538a994440a 100644
> > --- a/mm/mempolicy.c
> > +++ b/mm/mempolicy.c
> > @@ -3539,7 +3539,7 @@ static const struct kobj_type wi_ktype = {
> >   static int sysfs_wi_node_add(int nid)
> >   {
> > -	int ret = 0;
> > +	int ret;
> >   	char *name;
> >   	struct iw_node_attr *new_attr;
> > @@ -3569,6 +3569,7 @@ static int sysfs_wi_node_add(int nid)
> >   	if (wi_group->nattrs[nid]) {
> >   		mutex_unlock(&wi_group->kobj_lock);
> >   		pr_info("node%d already exists\n", nid);
> > +		ret = -EEXIST;
> 
> Returning -EEXIST here looks good to me, but could you remove the above pr_info
> as well?  I mean the following change is needed.
> 
> -		pr_info("node%d already exists\n", nid)
> +		ret = -EEXIST;
> 
> We don't need the above pr_info here because we delegate a warning message to
> its caller wi_node_notifier().
> 
> This can close another warning report below.
> https://lore.kernel.org/all/202505020458.yLHRAaW9-lkp@intel.com
> 
> If you apply my suggestion then please add
> 
> 	Reviewed-by: Honggyu Kim <honggyu.kim@...com>
> 

Rakie Kim was pretty confident that returning 0 was intentional.  Btw,
Smatch considers it intentional if the "ret = 0;" is within 5
lines of the goto.  Or we could add a comment, which wouldn't silence
the warning but it would help people reading the code.

regards,
dan carpenter