| Message ID | 20230905185309.131295-3-brgl@bgdev.pl (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | gpio: convert users to gpio_device_find() and remove gpiochip_find() | expand |
On Tue, Sep 05, 2023 at 08:52:50PM +0200, Bartosz Golaszewski wrote: > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > gpiochip_find() is wrong and its kernel doc is misleading as the > function doesn't return a reference to the gpio_chip but just a raw > pointer. The chip itself is not guaranteed to stay alive, in fact it can > be deleted at any point. Also: other than GPIO drivers themselves, > nobody else has any business accessing gpio_chip structs. > > Provide a new gpio_device_find() function that returns a real reference > to the opaque gpio_device structure that is guaranteed to stay alive for > as long as there are active users of it. ... > +/** > + * gpio_device_find() - find a specific GPIO device > + * @data: data to pass to match function > + * @match: Callback function to check gpio_chip > + * Returns: > + * New reference to struct gpio_device. I believe this is wrong location of the Return section. AFAIU how kernel doc uses section markers, this entire description becomes a Return(s) section. Have you tried to render man/html/pdf and see this? > + * Similar to bus_find_device(). It returns a reference to a gpio_device as > + * determined by a user supplied @match callback. The callback should return > + * 0 if the device doesn't match and non-zero if it does. If the callback > + * returns non-zero, this function will return to the caller and not iterate > + * over any more gpio_devices. > + * > + * The callback takes the GPIO chip structure as argument. During the execution > + * of the callback function the chip is protected from being freed. TODO: This > + * actually has yet to be implemented. > + * > + * If the function returns non-NULL, the returned reference must be freed by > + * the caller using gpio_device_put(). > + */ > +struct gpio_device *gpio_device_find(void *data, > + int (*match)(struct gpio_chip *gc, > + void *data)) One line? Or maybe a type for it? (gpio_match_fn, for example) > +{ > + struct gpio_device *gdev; > + > + guard(spinlock_irqsave)(&gpio_lock); > + > + list_for_each_entry(gdev, &gpio_devices, list) { > + if (gdev->chip && match(gdev->chip, data)) > + return gpio_device_get(gdev); > + } > + > + return NULL; > +} ... > +struct gpio_device *gpio_device_find(void *data, > + int (*match)(struct gpio_chip *gc, > + void *data)); Ditto.
On Tue, Sep 5, 2023 at 8:53 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote: > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > gpiochip_find() is wrong and its kernel doc is misleading as the > function doesn't return a reference to the gpio_chip but just a raw > pointer. The chip itself is not guaranteed to stay alive, in fact it can > be deleted at any point. Also: other than GPIO drivers themselves, > nobody else has any business accessing gpio_chip structs. > > Provide a new gpio_device_find() function that returns a real reference > to the opaque gpio_device structure that is guaranteed to stay alive for > as long as there are active users of it. > > Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> Reviewed-by: Linus Walleij <linus.walleij@linaro.org> Yours, Linus Walleij
On Wed, Sep 6, 2023 at 4:10 PM Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote: > > On Tue, Sep 05, 2023 at 08:52:50PM +0200, Bartosz Golaszewski wrote: > > From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org> > > > > gpiochip_find() is wrong and its kernel doc is misleading as the > > function doesn't return a reference to the gpio_chip but just a raw > > pointer. The chip itself is not guaranteed to stay alive, in fact it can > > be deleted at any point. Also: other than GPIO drivers themselves, > > nobody else has any business accessing gpio_chip structs. > > > > Provide a new gpio_device_find() function that returns a real reference > > to the opaque gpio_device structure that is guaranteed to stay alive for > > as long as there are active users of it. > > ... > > > +/** > > + * gpio_device_find() - find a specific GPIO device > > + * @data: data to pass to match function > > + * @match: Callback function to check gpio_chip > > > + * Returns: > > + * New reference to struct gpio_device. > > I believe this is wrong location of the Return section. > AFAIU how kernel doc uses section markers, this entire description becomes > a Return(s) section. Have you tried to render man/html/pdf and see this? > Yes, it works just fine. Try for yourself: scripts/kernel-doc -rst drivers/gpio/gpiolib.c Bart > > + * Similar to bus_find_device(). It returns a reference to a gpio_device as > > + * determined by a user supplied @match callback. The callback should return > > + * 0 if the device doesn't match and non-zero if it does. If the callback > > + * returns non-zero, this function will return to the caller and not iterate > > + * over any more gpio_devices. > > + * > > + * The callback takes the GPIO chip structure as argument. During the execution > > + * of the callback function the chip is protected from being freed. TODO: This > > + * actually has yet to be implemented. > > + * > > + * If the function returns non-NULL, the returned reference must be freed by > > + * the caller using gpio_device_put(). > > + */ > > +struct gpio_device *gpio_device_find(void *data, > > > + int (*match)(struct gpio_chip *gc, > > + void *data)) > > One line? > Or maybe a type for it? (gpio_match_fn, for example) > > > +{ > > + struct gpio_device *gdev; > > + > > + guard(spinlock_irqsave)(&gpio_lock); > > + > > + list_for_each_entry(gdev, &gpio_devices, list) { > > + if (gdev->chip && match(gdev->chip, data)) > > + return gpio_device_get(gdev); > > + } > > + > > + return NULL; > > +} > > ... > > > +struct gpio_device *gpio_device_find(void *data, > > + int (*match)(struct gpio_chip *gc, > > + void *data)); > > Ditto. > > > -- > With Best Regards, > Andy Shevchenko > >
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index f84ad54d8dbd..9e083ecb8df0 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -1014,16 +1014,10 @@ void gpiochip_remove(struct gpio_chip *gc) } EXPORT_SYMBOL_GPL(gpiochip_remove); -/** - * gpiochip_find() - iterator for locating a specific gpio_chip - * @data: data to pass to match function - * @match: Callback function to check gpio_chip +/* + * FIXME: This will be removed soon. * - * Similar to bus_find_device. It returns a reference to a gpio_chip as - * determined by a user supplied @match callback. The callback should return - * 0 if the device doesn't match and non-zero if it does. If the callback is - * non-zero, this function will return to the caller and not iterate over any - * more gpio_chips. + * This function is depracated, don't use. */ struct gpio_chip *gpiochip_find(void *data, int (*match)(struct gpio_chip *gc, @@ -1031,21 +1025,55 @@ struct gpio_chip *gpiochip_find(void *data, { struct gpio_device *gdev; struct gpio_chip *gc = NULL; - unsigned long flags; - spin_lock_irqsave(&gpio_lock, flags); - list_for_each_entry(gdev, &gpio_devices, list) - if (gdev->chip && match(gdev->chip, data)) { - gc = gdev->chip; - break; - } - - spin_unlock_irqrestore(&gpio_lock, flags); + gdev = gpio_device_find(data, match); + if (gdev) { + gc = gdev->chip; + gpio_device_put(gdev); + } return gc; } EXPORT_SYMBOL_GPL(gpiochip_find); +/** + * gpio_device_find() - find a specific GPIO device + * @data: data to pass to match function + * @match: Callback function to check gpio_chip + * + * Returns: + * New reference to struct gpio_device. + * + * Similar to bus_find_device(). It returns a reference to a gpio_device as + * determined by a user supplied @match callback. The callback should return + * 0 if the device doesn't match and non-zero if it does. If the callback + * returns non-zero, this function will return to the caller and not iterate + * over any more gpio_devices. + * + * The callback takes the GPIO chip structure as argument. During the execution + * of the callback function the chip is protected from being freed. TODO: This + * actually has yet to be implemented. + * + * If the function returns non-NULL, the returned reference must be freed by + * the caller using gpio_device_put(). + */ +struct gpio_device *gpio_device_find(void *data, + int (*match)(struct gpio_chip *gc, + void *data)) +{ + struct gpio_device *gdev; + + guard(spinlock_irqsave)(&gpio_lock); + + list_for_each_entry(gdev, &gpio_devices, list) { + if (gdev->chip && match(gdev->chip, data)) + return gpio_device_get(gdev); + } + + return NULL; +} +EXPORT_SYMBOL_GPL(gpio_device_find); + static int gpiochip_match_name(struct gpio_chip *gc, void *data) { const char *name = data; diff --git a/include/linux/gpio/driver.h b/include/linux/gpio/driver.h index a2060dc3344b..5c5029cec226 100644 --- a/include/linux/gpio/driver.h +++ b/include/linux/gpio/driver.h @@ -606,6 +606,10 @@ int devm_gpiochip_add_data_with_key(struct device *dev, struct gpio_chip *gc, struct gpio_chip *gpiochip_find(void *data, int (*match)(struct gpio_chip *gc, void *data)); +struct gpio_device *gpio_device_find(void *data, + int (*match)(struct gpio_chip *gc, + void *data)); + struct gpio_device *gpio_device_get(struct gpio_device *gdev); void gpio_device_put(struct gpio_device *gdev);