linux-kernel - Re: [PATCH 1/1] lib/vsprintf: Fix %pfwf when current node refcount == 0

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Message-ID: <ZVNoKAHlb1CXnND7@kekkonen.localdomain>
Date:   Tue, 14 Nov 2023 12:29:28 +0000
From:   Sakari Ailus <sakari.ailus@...ux.intel.com>
To:     Herve Codina <herve.codina@...tlin.com>
Cc:     Saravana Kannan <saravanak@...gle.com>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        linux-kernel@...r.kernel.org,
        Allan Nielsen <allan.nielsen@...rochip.com>,
        Horatiu Vultur <horatiu.vultur@...rochip.com>,
        Steen Hegelund <steen.hegelund@...rochip.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        stable@...r.kernel.org
Subject: Re: [PATCH 1/1] lib/vsprintf: Fix %pfwf when current node refcount
 == 0

Hi Herve,

On Tue, Nov 14, 2023 at 12:48:32PM +0100, Herve Codina wrote:
> Hi Sakari,
> 
> On Tue, 14 Nov 2023 11:28:43 +0000
> Sakari Ailus <sakari.ailus@...ux.intel.com> wrote:
> 
> > > --- a/lib/vsprintf.c
> > > +++ b/lib/vsprintf.c
> > > @@ -2108,8 +2108,8 @@ char *fwnode_full_name_string(struct fwnode_handle *fwnode, char *buf,
> > >  {
> > >  	int depth;
> > >  
> > > -	/* Loop starting from the root node to the current node. */
> > > -	for (depth = fwnode_count_parents(fwnode); depth >= 0; depth--) {
> > > +	/* Loop starting from the root node to the parent of current node. */
> > > +	for (depth = fwnode_count_parents(fwnode); depth > 0; depth--) {
> > >  		struct fwnode_handle *__fwnode =
> > >  			fwnode_get_nth_parent(fwnode, depth);  
> > 
> > How about, without changing the loop:
> > 
> > 		/*
> > 		 * Only get a reference for other nodes, fwnode refcount
> > 		 * may be 0 here.
> > 		 */
> > 		struct fwnode_handle *__fwnode =
> > 			depth ? fwnode_get_nth_parent(fwnode, depth) : fwnode;
> > 
> > >  
> > > @@ -2121,6 +2121,16 @@ char *fwnode_full_name_string(struct fwnode_handle *fwnode, char *buf,
> > >  		fwnode_handle_put(__fwnode);  
> > 
> > And:
> > 
> > 		if (__fwnode != fwnode)
> > 			fwnode_handle_put(__fwnode);
> > 
> 
> Sure.
> I will just change to keep the both tests consistent.
> I mean test with depth or test with __fwnode != fwnode but avoid
> mixing them.
> 
> What do you think about testing using depth in all cases and so:
> 	if (depth)
> 		fwnode_handle_put(__fwnode);

I'd compare fwnodes as we're putting __fwnode since we've gotten a
reference to fwnodes different from fwnode. I don't have a strong opinion
on this though, up to you.

-- 
Regards,

Sakari Ailus