| Message ID | 20160125153121.GA21093@amitoj-Inspiron-3542 (mailing list archive) |
|---|---|
| State | Accepted |
| Headers | show |
On Mon, Jan 25, 2016 at 09:01:21PM +0530, Amitoj Kaur Chawla wrote: > for_each_child_of_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_child_of_node(..., n) { > ... when != of_node_put(n) > when != e = n > ( > return n; > | > + of_node_put(n); > ? return ...; > ) > ... > } > // </smpl > > Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com> > --- > drivers/input/keyboard/cap11xx.c | 12 +++++++++--- > 1 file changed, 9 insertions(+), 3 deletions(-) > > diff --git a/drivers/input/keyboard/cap11xx.c b/drivers/input/keyboard/cap11xx.c > index 378db10..27cd7df 100644 > --- a/drivers/input/keyboard/cap11xx.c > +++ b/drivers/input/keyboard/cap11xx.c > @@ -304,8 +304,10 @@ static int cap11xx_init_leds(struct device *dev, > led->cdev.brightness = LED_OFF; > > error = of_property_read_u32(child, "reg", ®); > - if (error != 0 || reg >= num_leds) > - return -EINVAL; > + if (error != 0 || reg >= num_leds) { > + error = -EINVAL; > + goto putchild; Instead of jumping to a label I added of_node_put here and also below and applied, thank you. I believe there is another input driver that returns from for_each_child_of_node() without dropping reference. Thanks.
On Wed, 27 Jan 2016, Dmitry Torokhov wrote: > On Mon, Jan 25, 2016 at 09:01:21PM +0530, Amitoj Kaur Chawla wrote: > > for_each_child_of_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_child_of_node(..., n) { > > ... when != of_node_put(n) > > when != e = n > > ( > > return n; > > | > > + of_node_put(n); > > ? return ...; > > ) > > ... > > } > > // </smpl > > > > Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com> > > --- > > drivers/input/keyboard/cap11xx.c | 12 +++++++++--- > > 1 file changed, 9 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/input/keyboard/cap11xx.c b/drivers/input/keyboard/cap11xx.c > > index 378db10..27cd7df 100644 > > --- a/drivers/input/keyboard/cap11xx.c > > +++ b/drivers/input/keyboard/cap11xx.c > > @@ -304,8 +304,10 @@ static int cap11xx_init_leds(struct device *dev, > > led->cdev.brightness = LED_OFF; > > > > error = of_property_read_u32(child, "reg", ®); > > - if (error != 0 || reg >= num_leds) > > - return -EINVAL; > > + if (error != 0 || reg >= num_leds) { > > + error = -EINVAL; > > + goto putchild; > > Instead of jumping to a label I added of_node_put here and also below > and applied, thank you. Do you have a general strategy for this? I asked Arnd Bergmann, and he said that if things were shared and if all failures later in the function could use the shared label, then one should use a label. But I can see that there could be different opinions about it. Maybe two instances is not enough for sharing? Maybe the fact that the need for this error handling is limited to the loop means that there should never be sharing? thanks, julia > > I believe there is another input driver that returns from > for_each_child_of_node() without dropping reference. > > Thanks. > > -- > Dmitry > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Jan 28, 2016 at 10:16:39AM +0100, Julia Lawall wrote: > > > On Wed, 27 Jan 2016, Dmitry Torokhov wrote: > > > On Mon, Jan 25, 2016 at 09:01:21PM +0530, Amitoj Kaur Chawla wrote: > > > for_each_child_of_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_child_of_node(..., n) { > > > ... when != of_node_put(n) > > > when != e = n > > > ( > > > return n; > > > | > > > + of_node_put(n); > > > ? return ...; > > > ) > > > ... > > > } > > > // </smpl > > > > > > Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com> > > > --- > > > drivers/input/keyboard/cap11xx.c | 12 +++++++++--- > > > 1 file changed, 9 insertions(+), 3 deletions(-) > > > > > > diff --git a/drivers/input/keyboard/cap11xx.c b/drivers/input/keyboard/cap11xx.c > > > index 378db10..27cd7df 100644 > > > --- a/drivers/input/keyboard/cap11xx.c > > > +++ b/drivers/input/keyboard/cap11xx.c > > > @@ -304,8 +304,10 @@ static int cap11xx_init_leds(struct device *dev, > > > led->cdev.brightness = LED_OFF; > > > > > > error = of_property_read_u32(child, "reg", ®); > > > - if (error != 0 || reg >= num_leds) > > > - return -EINVAL; > > > + if (error != 0 || reg >= num_leds) { > > > + error = -EINVAL; > > > + goto putchild; > > > > Instead of jumping to a label I added of_node_put here and also below > > and applied, thank you. > > Do you have a general strategy for this? > > I asked Arnd Bergmann, and he said that if things were shared and if all > failures later in the function could use the shared label, then one should > use a label. But I can see that there could be different opinions about > it. Maybe two instances is not enough for sharing? Maybe the fact that > the need for this error handling is limited to the loop means that there > should never be sharing? I do not think I can formalize the rule well, it is a bit of everything: - the function is devm-ised and I do not like mixing "goto err" style of cleanups with automatic devm cleanup - there was no "goto err*" in the function before the change - as you mentioned the cleanup "belongs" to the loop - there were only 2 instances where we needed to do cleanup - amount of cleanup was minimal As a side not I am unhappy with this API as it is very similar list_for_each and for_each_set_bit, etc, so needing to drop reference when breaking/returning is quite unexpected ;( Thanks.
diff --git a/drivers/input/keyboard/cap11xx.c b/drivers/input/keyboard/cap11xx.c index 378db10..27cd7df 100644 --- a/drivers/input/keyboard/cap11xx.c +++ b/drivers/input/keyboard/cap11xx.c @@ -304,8 +304,10 @@ static int cap11xx_init_leds(struct device *dev, led->cdev.brightness = LED_OFF; error = of_property_read_u32(child, "reg", ®); - if (error != 0 || reg >= num_leds) - return -EINVAL; + if (error != 0 || reg >= num_leds) { + error = -EINVAL; + goto putchild; + } led->reg = reg; led->priv = priv; @@ -314,13 +316,17 @@ static int cap11xx_init_leds(struct device *dev, error = devm_led_classdev_register(dev, &led->cdev); if (error) - return error; + goto putchild; priv->num_leds++; led++; } return 0; + +putchild: + of_node_put(child); + return error; } #else static int cap11xx_init_leds(struct device *dev,
for_each_child_of_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_child_of_node(..., n) { ... when != of_node_put(n) when != e = n ( return n; | + of_node_put(n); ? return ...; ) ... } // </smpl Signed-off-by: Amitoj Kaur Chawla <amitoj1606@gmail.com> --- drivers/input/keyboard/cap11xx.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)