| Message ID | 1500108152-1812-1-git-send-email-Julia.Lawall@lip6.fr (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Eduardo Valentin |
| Headers | show |
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.Lawall@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. Cheers Jon
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.Lawall@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 majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
On Mon, Jul 17, 2017 at 04:42:38PM +0200, Julia Lawall wrote: > > > 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.Lawall@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, I agree with Jon here. Better if fixed in the API itself. Are you still planning on sending a fix for this?
On Mon, 4 Dec 2017, Eduardo Valentin wrote: > On Mon, Jul 17, 2017 at 04:42:38PM +0200, Julia Lawall wrote: > > > > > > 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.Lawall@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, I agree with Jon here. Better if fixed in the API itself. Are you > still planning on sending a fix for this? This has fallen off my stack, and I'mnot sure that Ican get to it in the short term. julia
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; }
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.Lawall@lip6.fr> --- drivers/thermal/tegra/soctherm.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)