On Mon, 17 Jul 2017, Jon Hunter wrote:
> > On 15/07/17 09:42, Julia Lawall wrote: > > Device node iterators perform an of_node_put on each iteration, so putting > > an of_node_put before a continue results in a double put. > > > > The semantic match that finds this problem is as follows > > (http://coccinelle.lip6.fr): > > > > // <smpl> > > @@ > > expression e1; > > local idexpression child; > > iterator name for_each_child_of_node; > > @@ > > > > for_each_child_of_node(e1,child) { > > ... when != of_node_get(child) > > * of_node_put(child); > > ... > > * continue; > > } > > // </smpl> > > > > Furthermore, the call to thermal_of_cooling_device_register immediately > > calls __thermal_cooling_device_register with the same arguments. The > > latter function stores the device node argument, which is the second > > argument of for_each_child_of_node, in the returned thermal_cooling_device > > structure. This returned structure is then stored in the cdev field of > > stc. Thus it seems that the second argument of for_each_child_of_node > > escapes the scope of the for_each_child_of_node, so an explicit of_node_get > > on success of thermal_of_cooling_device_register is also needed. > > > > Signed-off-by: Julia Lawall <julia.law...@lip6.fr> > > > > --- > > drivers/thermal/tegra/soctherm.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/thermal/tegra/soctherm.c > > b/drivers/thermal/tegra/soctherm.c > > index 7d2db23..10f4fdd 100644 > > --- a/drivers/thermal/tegra/soctherm.c > > +++ b/drivers/thermal/tegra/soctherm.c > > @@ -1014,7 +1014,6 @@ static void soctherm_init_hw_throt_cdev(struct > > platform_device *pdev) > > tcd = thermal_of_cooling_device_register(np_stcc, > > (char *)name, ts, > > &throt_cooling_ops); > > - of_node_put(np_stcc); > > if (IS_ERR_OR_NULL(tcd)) { > > dev_err(dev, > > "throttle-cfg: %s: failed to register cooling > > device\n", > > @@ -1022,6 +1021,7 @@ static void soctherm_init_hw_throt_cdev(struct > > platform_device *pdev) > > continue; > > } > > > > + of_node_get(np_stcc); > > stc->cdev = tcd; > > stc->init = true; > > } > > Thanks for fixing this. However, I am wondering if it is better for the > 'of_node_get' to be placed within the > thermal_of_cooling_device_register() function as it seems a bit odd if > the caller needs to know that this is being stored for later use. > > Also, taking a quick look, I see a couple other drivers calling > thermal_of_cooling_device_register() and they are also not calling > of_node_get on success. So it maybe easier to fix placing it in the > thermal_of_cooling_device_register() function. I'm not an expert, but I had the impression that from some call sites, the get would have been done already, because the argument is already stored in some structure. I can check more exhaustively. julia > > Cheers > Jon > > -- > nvpublic > -- > To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in > the body of a message to majord...@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
