Re: [PATCH 1/6] clk: Handle error pointers in clk_valid()

["Michal Suchánek" <msuchanek@suse.de>]

On Mon, Feb 20, 2023 at 10:57:17AM -0500, Sean Anderson wrote:
> 
> On 2/20/23 05:46, Michal Suchánek wrote:
> > On Sun, Feb 19, 2023 at 11:59:34PM -0600, Samuel Holland wrote:
> > > Some clk uclass functions, such as devm_clk_get() and clk_get_parent(),
> > > return error pointers. clk_valid() should not consider these pointers
> > > to be valid.
> > > 
> > > Fixes: 8a1661f20e6c ("drivers: clk: Handle gracefully NULL pointers")
> > > Signed-off-by: Samuel Holland <samuel@sholland.org>
> > > ---
> > > 
> > >   include/clk.h | 2 +-
> > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/include/clk.h b/include/clk.h
> > > index d91285235f7..4acb878ec6d 100644
> > > --- a/include/clk.h
> > > +++ b/include/clk.h
> > > @@ -671,7 +671,7 @@ static inline bool clk_dev_binded(struct clk *clk)
> > >    */
> > >   static inline bool clk_valid(struct clk *clk)
> > >   {
> > > -	return clk && !!clk->dev;
> > > +	return clk && !IS_ERR(clk) && !!clk->dev;
> > >   }
> > >   int soc_clk_dump(void);
> > 
> > Maybe it would be better to avoid the error pointers instead, there
> > should not be that many places where they are returned.
> 
> This not quite the right way to phrase this. Instead, I would ask: where
> are places where the return value is not checked correctly? It's perfectly

Pretty much everywhere where clk_get_parent is used outside of core code
absolutely no error checking is done.

> fine to pass NULL or uninitialized clocks to other clock functions, but it's
> not OK to ignore errors.

Is there some documentation on what is the distinction, specifically?

If there isn't it's meaningless and NULL can be returned on error
simplifying the code, thinking about the code, debugging, pretty much
everything.

Thanks

Michal