Hi Neil,
On Sun, Dec 30, 2018 at 4:58 AM NeilBrown <neil@xxxxxxxxxx> wrote:
>
> On Thu, Jun 07 2018, Sergio Paracuellos wrote:
>
> > Using 'function' and 'groups' bindings in the device tree give the
> > posibility of refactor 'rt2880_pinctrl_dt_node_to_map' and simplify
> > it a lot. Make use of the 'of_property_count_strings' function to get
> > number of groups for the node and iterate over the groups using
> > 'of_property_for_each_string' calling 'pinctrl_utils_add_map_mux'
> > function which is the same of the custom function in this driver code
> > 'rt2880_pinctrl_dt_subnode_to_map' which is not needed anymore.
> >
> > Signed-off-by: Sergio Paracuellos <sergio.paracuellos@xxxxxxxxx>
>
> Hi Sergio,
> I've just noticed a problem with this code. The problem existed before
> your patch - you didn't introduce it. But maybe you are more familiar
> with the code and might like to fix it...
>
>
> > ---
> > drivers/staging/mt7621-pinctrl/pinctrl-rt2880.c | 60 ++++++++-----------------
> > 1 file changed, 18 insertions(+), 42 deletions(-)
> >
> > diff --git a/drivers/staging/mt7621-pinctrl/pinctrl-rt2880.c b/drivers/staging/mt7621-pinctrl/pinctrl-rt2880.c
> > index 84494a1..8291ec0 100644
> > --- a/drivers/staging/mt7621-pinctrl/pinctrl-rt2880.c
> > +++ b/drivers/staging/mt7621-pinctrl/pinctrl-rt2880.c
> ...
>
> > static int rt2880_pinctrl_dt_node_to_map(struct pinctrl_dev *pctrldev,
> > struct device_node *np_config,
> > struct pinctrl_map **map,
> > unsigned int *num_maps)
>
> num_maps passed in ( from dt_to_map_one_config in
> drivers/pinctrl/devicetree.c)
> is the address of an uninitialised variable - has the value -1681671408 in one test
> run.
>
>
> > {
> > struct rt2880_priv *p = pinctrl_dev_get_drvdata(pctrldev);
> > + struct property *prop;
> > + const char *function_name, *group_name;
> > int ret;
> > - int max_maps = 0;
> > + int ngroups;
> > unsigned int reserved_maps = 0;
> > - struct pinctrl_map *tmp;
> > - struct device_node *np;
> >
> > - for_each_child_of_node(np_config, np) {
> > - int ret = of_property_count_strings(np, "ralink,group");
> > -
> > - if (ret >= 0)
> > - max_maps += ret;
> > + ngroups = of_property_count_strings(np_config, "groups");
> > + if (!ngroups) {
> > + dev_err(p->dev, "missing groups property in node %s\n",
> > + np_config->name);
> > + return -EINVAL;
> > }
> >
> > - if (!max_maps)
> > - return max_maps;
> > -
> > ret = pinctrl_utils_reserve_map(pctrldev, map, &reserved_maps,
> > - num_maps, max_maps);
> > + num_maps, ngroups);
>
> pinctrl_utils_reserve_map() expects *num_maps to be initialized here.
> It does a memory allocation based on the value, and triggers a warning
> for me:
> if (unlikely(order >= MAX_ORDER)) {
> WARN_ON_ONCE(!(gfp_mask & __GFP_NOWARN));
> return NULL;
> }
>
>
> > if (ret) {
> > dev_err(p->dev, "can't reserve map: %d\n", ret);
> > return ret;
> > }
> >
> > - tmp = *map;
> > -
> > - for_each_child_of_node(np_config, np)
> > - rt2880_pinctrl_dt_subnode_to_map(pctrldev, np, &tmp);
> > - *num_maps = max_maps;
>
> Previously *num_maps was initialised here - clearly too late. Now it
> isn't initialised at all.
> Do you know what value it should be set to?
In my staging tree the code is a bit different and the patch you are pointing
out obviously is wrong because the value of 'num_maps' should be the number
of bindings where the "group" property is set and not the "groups" one
which is not
a standard binding. So what I have is:
static int rt2880_pinctrl_dt_node_to_map(struct pinctrl_dev *pctrldev,
struct device_node *np_config,
struct pinctrl_map **map,
unsigned int *num_maps)
{
struct rt2880_priv *p = pinctrl_dev_get_drvdata(pctrldev);
struct property *prop;
const char *function_name, *group_name;
int ret;
int ngroups = 0;
unsigned int reserved_maps = 0;
for_each_node_with_property(np_config, "group")
ngroups++;
*map = NULL;
ret = pinctrl_utils_reserve_map(pctrldev, map, &reserved_maps,
num_maps, ngroups);
if (ret) {
dev_err(p->dev, "can't reserve map: %d\n", ret);
return ret;
}
of_property_for_each_string(np_config, "group", prop, group_name) {
ret = pinctrl_utils_add_map_mux(pctrldev, map, &reserved_maps,
num_maps, group_name,
function_name);
if (ret) {
dev_err(p->dev, "can't add map: %d\n", ret);
return ret;
}
}
return 0;
}
There was a fix, about the ngroups property to be initialized to zero
so at least
even if there is no bindings defined in the DT the value should be initialized.
See:
https://lkml.org/lkml/2018/11/11/115
Am I missing something?
>
> Thanks,
> NeilBrown
>
Hope this helps.
Best regards,
Sergio Paracuellos
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