Message ID | 20211124122850.7095-2-brgl@bgdev.pl |
---|---|
State | New |
Headers | show |
Series | [v3,1/2] gpiolib: improve coding style for local variables | expand |
On Wed, Nov 24, 2021 at 01:28:50PM +0100, Bartosz Golaszewski wrote: > Several drivers read the 'ngpios' device property on their own, but > since it's defined as a standard GPIO property in the device tree bindings > anyway, it's a good candidate for generalization. If the driver didn't > set its gc->ngpio, try to read the 'ngpios' property from the GPIO > device's firmware node before bailing out. > Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl> > Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > --- > v1 -> v2: > - use device_property_read_u32() instead of fwnode_property_read_u32() > - reverse the error check logic > > v2 -> v3: > - don't shadow errors other than -ENODATA in device_property_read_u32() > > drivers/gpio/gpiolib.c | 15 ++++++++++++--- > 1 file changed, 12 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index ede8b8a7aa18..f79fd2551cf7 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -599,6 +599,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, > int base = gc->base; > unsigned int i; > int ret = 0; > + u32 ngpios; > > /* > * First: allocate and populate the internal stat container, and > @@ -647,9 +648,17 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, > } > if (gc->ngpio == 0) { > - chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > - ret = -EINVAL; > - goto err_free_descs; > + ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); > + if (ret) { > + if (ret == -ENODATA) { > + chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > + ret = -EINVAL; > + } > + > + goto err_free_descs; > + } And if the property returns 0 in ngpios? What about the modified suggestion from previous version: if (gc->ngpio == 0) { ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); /* * -ENODATA means that there is no property found and * we want to issue the error message to the user. Besides * that, we want to return different error code to state * that supplied value is not valid. */ if (ret == -ENODATA) ngpios = 0; else if (ret) return ret; gc->ngpio = ngpios; } if (gc->ngpio == 0) { chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); ret = -EINVAL; goto err_free_descs; } ? > + gc->ngpio = ngpios; > } > > if (gc->ngpio > FASTPATH_NGPIO) > -- > 2.25.1 >
On Wed, Nov 24, 2021 at 04:46:58PM +0200, Andy Shevchenko wrote: > On Wed, Nov 24, 2021 at 01:28:50PM +0100, Bartosz Golaszewski wrote: > > Several drivers read the 'ngpios' device property on their own, but > > since it's defined as a standard GPIO property in the device tree bindings > > anyway, it's a good candidate for generalization. If the driver didn't > > set its gc->ngpio, try to read the 'ngpios' property from the GPIO > > device's firmware node before bailing out. ... > What about the modified suggestion from previous version: > > if (gc->ngpio == 0) { > ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); > /* > * -ENODATA means that there is no property found and > * we want to issue the error message to the user. Besides > * that, we want to return different error code to state > * that supplied value is not valid. > */ > if (ret == -ENODATA) > ngpios = 0; > else if (ret) > return ret; > > gc->ngpio = ngpios; > } > > if (gc->ngpio == 0) { > chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > ret = -EINVAL; > goto err_free_descs; > } > > ? If you okay to go with this code, Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
On Wed, Nov 24, 2021 at 3:47 PM Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote: > > On Wed, Nov 24, 2021 at 01:28:50PM +0100, Bartosz Golaszewski wrote: > > Several drivers read the 'ngpios' device property on their own, but > > since it's defined as a standard GPIO property in the device tree bindings > > anyway, it's a good candidate for generalization. If the driver didn't > > set its gc->ngpio, try to read the 'ngpios' property from the GPIO > > device's firmware node before bailing out. > > > Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl> > > Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > Reviewed-by: Linus Walleij <linus.walleij@linaro.org> > > --- > > v1 -> v2: > > - use device_property_read_u32() instead of fwnode_property_read_u32() > > - reverse the error check logic > > > > v2 -> v3: > > - don't shadow errors other than -ENODATA in device_property_read_u32() > > > > drivers/gpio/gpiolib.c | 15 ++++++++++++--- > > 1 file changed, 12 insertions(+), 3 deletions(-) > > > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > > index ede8b8a7aa18..f79fd2551cf7 100644 > > --- a/drivers/gpio/gpiolib.c > > +++ b/drivers/gpio/gpiolib.c > > @@ -599,6 +599,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, > > int base = gc->base; > > unsigned int i; > > int ret = 0; > > + u32 ngpios; > > > > /* > > * First: allocate and populate the internal stat container, and > > @@ -647,9 +648,17 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, > > } > > > if (gc->ngpio == 0) { > > - chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > > - ret = -EINVAL; > > - goto err_free_descs; > > + ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); > > + if (ret) { > > + if (ret == -ENODATA) { > > + chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > > + ret = -EINVAL; > > + } > > + > > + goto err_free_descs; > > + } > > And if the property returns 0 in ngpios? > > What about the modified suggestion from previous version: > > if (gc->ngpio == 0) { > ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); The comment is a good idea but other than that - it's overcomplicating things. > if (ret == -ENODATA) > ngpios = 0; > else if (ret) > return ret; You still need to goto err_free_descs here. > > gc->ngpio = ngpios; > } > > if (gc->ngpio == 0) { Why check that again? We already know the driver set it to 0, we checked it a couple lines before. If we can't get the setting from the properties then it won't be non 0 here right? > chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > ret = -EINVAL; > goto err_free_descs; > } > > ? > > > + gc->ngpio = ngpios; > > } > > > > if (gc->ngpio > FASTPATH_NGPIO) > > -- > > 2.25.1 > > > > -- > With Best Regards, > Andy Shevchenko > > I suggest the following: diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index ede8b8a7aa18..08c1e8fc0dfa 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -599,6 +599,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, int base = gc->base; unsigned int i; int ret = 0; + u32 ngpios; /* * First: allocate and populate the internal stat container, and @@ -647,9 +648,23 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, } if (gc->ngpio == 0) { - chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); - ret = -EINVAL; - goto err_free_descs; + /* + * If the driver didn't specify the number of GPIOs, try to + * get this value from the device properties as a fall-back. + */ + ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); + if (ret) { + /* + * -ENODATA means that there is no property found and + * we want to issue the error message to the user. + * Besides that, we want to return different error code + * to state that supplied value is not valid. + * */ + if (ret == -ENODATA) { + chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); + ret = -EINVAL; + } + + goto err_free_descs; + } + + gc->ngpio = ngpios; } if (gc->ngpio > FASTPATH_NGPIO)
On Thu, Nov 25, 2021 at 11:10:08AM +0100, Bartosz Golaszewski wrote: > On Wed, Nov 24, 2021 at 3:47 PM Andy Shevchenko > <andriy.shevchenko@linux.intel.com> wrote: > > On Wed, Nov 24, 2021 at 01:28:50PM +0100, Bartosz Golaszewski wrote: ... > > > + ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); > > > + if (ret) { > > > + if (ret == -ENODATA) { > > > + chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > > > + ret = -EINVAL; > > > + } > > > + > > > + goto err_free_descs; > > > + } > > > > And if the property returns 0 in ngpios? > > > > What about the modified suggestion from previous version: > > > > if (gc->ngpio == 0) { > > ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); > The comment is a good idea but other than that - it's overcomplicating things. I don't think so. It is plain and self-explaining each step. See at the end of the message how. > > if (ret == -ENODATA) > > ngpios = 0; > > else if (ret) > > return ret; > You still need to goto err_free_descs here. Right, this doesn't affect the main point / logic here. > > gc->ngpio = ngpios; > > } > > > > if (gc->ngpio == 0) { > > Why check that again? We already know the driver set it to 0, we > checked it a couple lines before. If we can't get the setting from the > properties then it won't be non 0 here right? No, it's not right. The check is needed to tell that properties supplied 0. > > chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > > ret = -EINVAL; > > goto err_free_descs; > > } > > > > ? > > > > > + gc->ngpio = ngpios; > > > } > > > > > > if (gc->ngpio > FASTPATH_NGPIO) > I suggest the following: It's buggy as submitted version (I actually haven't found any difference in the code, but comments). You see, I propose less changes and straight forward logic: 1. Check if the supplied ->ngpio equal to 0 2. If so, try device properties 2.1. If there is no property found, make sure we a) don't use uninitialized variable, b) we don't change ->ngpio, so it stays 0 2.2. If there is an error, return it as is to the caller 2.3. Assign ->ngpio by value from property (which very well may be 0!) 3. Check ->ngpio for 0 again, if so, issue a message and return -EINVAL to the user. We have three places where ->ngpio can be 0, all of them I covered.
On Thu, Nov 25, 2021 at 12:18 PM Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote: > > On Thu, Nov 25, 2021 at 11:10:08AM +0100, Bartosz Golaszewski wrote: > > On Wed, Nov 24, 2021 at 3:47 PM Andy Shevchenko > > <andriy.shevchenko@linux.intel.com> wrote: > > > On Wed, Nov 24, 2021 at 01:28:50PM +0100, Bartosz Golaszewski wrote: > > ... > > > > > + ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); > > > > + if (ret) { > > > > + if (ret == -ENODATA) { > > > > + chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > > > > + ret = -EINVAL; > > > > + } > > > > + > > > > + goto err_free_descs; > > > > + } > > > > > > And if the property returns 0 in ngpios? > > > > > > What about the modified suggestion from previous version: > > > > > > if (gc->ngpio == 0) { > > > ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); > > > The comment is a good idea but other than that - it's overcomplicating things. > > I don't think so. It is plain and self-explaining each step. See at the end of > the message how. > > > > if (ret == -ENODATA) > > > ngpios = 0; > > > else if (ret) > > > return ret; > > > You still need to goto err_free_descs here. > > Right, this doesn't affect the main point / logic here. > > > > gc->ngpio = ngpios; > > > } > > > > > > if (gc->ngpio == 0) { > > > > Why check that again? We already know the driver set it to 0, we > > checked it a couple lines before. If we can't get the setting from the > > properties then it won't be non 0 here right? > > No, it's not right. The check is needed to tell that properties supplied 0. > > > > chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); > > > ret = -EINVAL; > > > goto err_free_descs; > > > } > > > > > > ? > > > > > > > + gc->ngpio = ngpios; > > > > } > > > > > > > > if (gc->ngpio > FASTPATH_NGPIO) > > > I suggest the following: > > It's buggy as submitted version (I actually haven't found any difference in > the code, but comments). > > You see, I propose less changes and straight forward logic: > > 1. Check if the supplied ->ngpio equal to 0 > 2. If so, try device properties > 2.1. If there is no property found, make sure we a) don't use uninitialized > variable, b) we don't change ->ngpio, so it stays 0 > 2.2. If there is an error, return it as is to the caller > 2.3. Assign ->ngpio by value from property (which very well may be 0!) Ok, this is the thing I didn't realize, the property can indeed be 0 so your approach is correct. Bart > 3. Check ->ngpio for 0 again, if so, issue a message and return -EINVAL to > the user. > > We have three places where ->ngpio can be 0, all of them I covered. > > -- > With Best Regards, > Andy Shevchenko > >
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index ede8b8a7aa18..f79fd2551cf7 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -599,6 +599,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, int base = gc->base; unsigned int i; int ret = 0; + u32 ngpios; /* * First: allocate and populate the internal stat container, and @@ -647,9 +648,17 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, } if (gc->ngpio == 0) { - chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); - ret = -EINVAL; - goto err_free_descs; + ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios); + if (ret) { + if (ret == -ENODATA) { + chip_err(gc, "tried to insert a GPIO chip with zero lines\n"); + ret = -EINVAL; + } + + goto err_free_descs; + } + + gc->ngpio = ngpios; } if (gc->ngpio > FASTPATH_NGPIO)