Re: [PATCH 10/11] soc: ti: knav_qmss_queue: use of_property_read_bool

Re: [PATCH 10/11] soc: ti: knav_qmss_queue: use of_property_read_bool

[Robin Murphy]

Hi Julia,

On 05/08/16 09:56, Julia Lawall wrote:
> Use of_property_read_bool to check for the existence of a property.

This caught my eye since Rob told me off for doing the same recently[1].

> The semantic patch that makes this change is as follows:
> (http://coccinelle.lip6.fr/)
> 
> // <smpl>
> @@
> expression e1,e2;
> statement S2,S1;
> @@
> -       if (of_get_property(e1,e2,NULL))
> +       if (of_property_read_bool(e1,e2))
>         S1 else S2
> // </smpl>
> 
> Signed-off-by: Julia Lawall <Julia.Lawall-L2FTfq7BK8M@public.gmane.org>
> 
> ---
>  drivers/soc/ti/knav_qmss_queue.c |    2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/soc/ti/knav_qmss_queue.c b/drivers/soc/ti/knav_qmss_queue.c
> index b73e353..56b5d7c 100644
> --- a/drivers/soc/ti/knav_qmss_queue.c
> +++ b/drivers/soc/ti/knav_qmss_queue.c
> @@ -1240,7 +1240,7 @@ static int knav_setup_queue_range(struct knav_device *kdev,
>  	if (of_get_property(node, "qalloc-by-id", NULL))

According to the binding, "qalloc-by-id" _is_ a boolean property, so
this one really does deserve to be of_property_read_bool()...

>  		range->flags |= RANGE_RESERVED;
>  
> -	if (of_get_property(node, "accumulator", NULL)) {
> +	if (of_property_read_bool(node, "accumulator")) {

...whereas "accumulator" must have a value, so this isn't technically
appropriate. In general, most of these "if the property exists, read the
property and do stuff" checks are probably a sign of code that could be
simplified by refactoring the "do stuff" step to just specifically
handle the "read the property" step returning -EINVAL when it's not present.

Robin.

[1]:https://www.mail-archive.com/iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org/msg13375.html

>  		ret = knav_init_acc_range(kdev, node, range);
>  		if (ret < 0) {
>  			devm_kfree(dev, range);
> 
> 
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> 

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Re: [PATCH 10/11] soc: ti: knav_qmss_queue: use of_property_read_bool

[Julia Lawall]

On Fri, 5 Aug 2016, Robin Murphy wrote:

> Hi Julia,
>
> On 05/08/16 09:56, Julia Lawall wrote:
> > Use of_property_read_bool to check for the existence of a property.
>
> This caught my eye since Rob told me off for doing the same recently[1].
>
> > The semantic patch that makes this change is as follows:
> > (http://coccinelle.lip6.fr/)
> >
> > // <smpl>
> > @@
> > expression e1,e2;
> > statement S2,S1;
> > @@
> > -       if (of_get_property(e1,e2,NULL))
> > +       if (of_property_read_bool(e1,e2))
> >         S1 else S2
> > // </smpl>
> >
> > Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
> >
> > ---
> >  drivers/soc/ti/knav_qmss_queue.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/soc/ti/knav_qmss_queue.c b/drivers/soc/ti/knav_qmss_queue.c
> > index b73e353..56b5d7c 100644
> > --- a/drivers/soc/ti/knav_qmss_queue.c
> > +++ b/drivers/soc/ti/knav_qmss_queue.c
> > @@ -1240,7 +1240,7 @@ static int knav_setup_queue_range(struct knav_device *kdev,
> >  	if (of_get_property(node, "qalloc-by-id", NULL))
>
> According to the binding, "qalloc-by-id" _is_ a boolean property, so
> this one really does deserve to be of_property_read_bool()...
>
> >  		range->flags |= RANGE_RESERVED;
> >
> > -	if (of_get_property(node, "accumulator", NULL)) {
> > +	if (of_property_read_bool(node, "accumulator")) {
>
> ...whereas "accumulator" must have a value, so this isn't technically
> appropriate. In general, most of these "if the property exists, read the
> property and do stuff" checks are probably a sign of code that could be
> simplified by refactoring the "do stuff" step to just specifically
> handle the "read the property" step returning -EINVAL when it's not present.

Thanks for the very helpful feedback.  I will rethink the patch set in
light of this information.

julia

> Robin.
>
> [1]:https://www.mail-archive.com/iommu@lists.linux-foundation.org/msg13375.html
>
> >  		ret = knav_init_acc_range(kdev, node, range);
> >  		if (ret < 0) {
> >  			devm_kfree(dev, range);
> >
> >
> > _______________________________________________
> > linux-arm-kernel mailing list
> > linux-arm-kernel@lists.infradead.org
> > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
> >
>
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