On Mon, 25 Jan 2016, [email protected] wrote:
> On Fri, Jan 22, 2016 at 11:38:38PM +0530, Amitoj Kaur Chawla wrote:
> > for_each_compatible_node performs an of_node_get on each iteration, so
> > to break out of the loop an of_node_put is required.
> >
> > Found using Coccinelle. The semantic patch used for this is as follows:
> >
> > // <smpl>
> > @@
> > expression e;
> > local idexpression n;
> > @@
> >
> > for_each_compatible_node(n, ...) {
> > ... when != of_node_put(n)
> > when != e = n
> > (
> > return n;
> > + of_node_put(n);
> > ? return ...;
> > )
> > ...
> > }
> > // </smpl>
> >
> > Signed-off-by: Amitoj Kaur Chawla <[email protected]>
>
> Hi Amitoj,
>
> > ---
> > drivers/bus/vexpress-config.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c
> > index 6575c0f..c3cb76b 100644
> > --- a/drivers/bus/vexpress-config.c
> > +++ b/drivers/bus/vexpress-config.c
> > @@ -192,8 +192,10 @@ static int __init vexpress_config_init(void)
> > /* Need the config devices early, before the "normal" devices... */
> > for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") {
> > err = vexpress_config_populate(node);
> > - if (err)
> > + if (err) {
> > + of_node_put(node);
> > break;
> > + }
>
> This automatically generated patch only solves half of the problem (for the
> error
> path).
>
> > }
> >
> > return err;
> > --
> > 1.9.1
> >
>
> I feel that a better patch would be the following, where the node is released
> regardless of the result of vexpress_config_populate().
>
> --8<--------------------------------------------------------------------------
> diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c
> index 6575c0f..c57453d 100644
> --- a/drivers/bus/vexpress-config.c
> +++ b/drivers/bus/vexpress-config.c
> @@ -192,6 +192,7 @@ static int __init vexpress_config_init(void)
> /* Need the config devices early, before the "normal" devices... */
> for_each_compatible_node(node, NULL, "arm,vexpress,config-bus") {
> err = vexpress_config_populate(node);
> + of_node_put(node);
This is not correct. for_each_compatible_node will do the free if you go
around the loop. This change would lead to a double free in the non error
case.
julia
> if (err)
> break;
> }
> -->8--------------------------------------------------------------------------
>
> Best regards,
> Liviu
>
> --
> ====================
> | I would like to |
> | fix the world, |
> | but they're not |
> | giving me the |
> \ source code! /
> ---------------
> ¯\_(ツ)_/¯
>
