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SubjectRe: [PATCH v3 1/3] leds: triggers: provide led_trigger_register_format()
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Hi Uwe,

Thank you for the patch. It looks fine, but please split
the drivers/net/can/led.c related changes into a separate one.

Best regards,
Jacek Anaszewski

On 05/08/2018 12:05 PM, Uwe Kleine-König wrote:
> This allows one to simplify drivers that provide a trigger with a
> non-constant name (e.g. one trigger per device with the trigger name
> depending on the device's name).
>
> Internally the memory the name member of struct led_trigger points to
> now always allocated dynamically instead of just taken from the caller.
>
> The function led_trigger_rename_static() must be changed accordingly and
> was renamed to led_trigger_rename() for consistency, with the only user
> adapted.
>
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
> drivers/leds/led-triggers.c | 84 +++++++++++++++++++++++++++----------
> drivers/net/can/led.c | 6 +--
> include/linux/leds.h | 30 +++++++------
> 3 files changed, 81 insertions(+), 39 deletions(-)
>
> diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
> index 431123b048a2..5d8bb504b07b 100644
> --- a/drivers/leds/led-triggers.c
> +++ b/drivers/leds/led-triggers.c
> @@ -175,18 +175,34 @@ void led_trigger_set_default(struct led_classdev *led_cdev)
> }
> EXPORT_SYMBOL_GPL(led_trigger_set_default);
>
> -void led_trigger_rename_static(const char *name, struct led_trigger *trig)
> +int led_trigger_rename(struct led_trigger *trig, const char *fmt, ...)
> {
> - /* new name must be on a temporary string to prevent races */
> - BUG_ON(name == trig->name);
> + const char *prevname;
> + const char *newname;
> + va_list args;
> +
> + if (!trig)
> + return 0;
> +
> + va_start(args, fmt);
> + newname = kvasprintf_const(GFP_KERNEL, fmt, args);
> + va_end(args);
> +
> + if (!newname) {
> + pr_err("Failed to allocate new name for trigger %s\n", trig->name);
> + return -ENOMEM;
> + }
>
> down_write(&triggers_list_lock);
> - /* this assumes that trig->name was originaly allocated to
> - * non constant storage */
> - strcpy((char *)trig->name, name);
> + prevname = trig->name;
> + trig->name = newname;
> up_write(&triggers_list_lock);
> +
> + kfree_const(prevname);
> +
> + return 0;
> }
> -EXPORT_SYMBOL_GPL(led_trigger_rename_static);
> +EXPORT_SYMBOL_GPL(led_trigger_rename);
>
> /* LED Trigger Interface */
>
> @@ -333,34 +349,56 @@ void led_trigger_blink_oneshot(struct led_trigger *trig,
> }
> EXPORT_SYMBOL_GPL(led_trigger_blink_oneshot);
>
> -void led_trigger_register_simple(const char *name, struct led_trigger **tp)
> +int led_trigger_register_format(struct led_trigger **tp, const char *fmt, ...)
> {
> + va_list args;
> struct led_trigger *trig;
> - int err;
> + int err = -ENOMEM;
> + const char *name;
> +
> + va_start(args, fmt);
> + name = kvasprintf_const(GFP_KERNEL, fmt, args);
> + va_end(args);
>
> trig = kzalloc(sizeof(struct led_trigger), GFP_KERNEL);
>
> - if (trig) {
> - trig->name = name;
> - err = led_trigger_register(trig);
> - if (err < 0) {
> - kfree(trig);
> - trig = NULL;
> - pr_warn("LED trigger %s failed to register (%d)\n",
> - name, err);
> - }
> - } else {
> - pr_warn("LED trigger %s failed to register (no memory)\n",
> - name);
> - }
> + if (!name || !trig)
> + goto err;
> +
> + trig->name = name;
> +
> + err = led_trigger_register(trig);
> + if (err < 0)
> + goto err;
> +
> *tp = trig;
> +
> + return 0;
> +
> +err:
> + kfree(trig);
> + kfree_const(name);
> +
> + *tp = NULL;
> +
> + return err;
> +}
> +EXPORT_SYMBOL_GPL(led_trigger_register_format);
> +
> +void led_trigger_register_simple(const char *name, struct led_trigger **tp)
> +{
> + int ret = led_trigger_register_format(tp, "%s", name);
> + if (ret < 0)
> + pr_warn("LED trigger %s failed to register (%d)\n", name, ret);
> }
> EXPORT_SYMBOL_GPL(led_trigger_register_simple);
>
> void led_trigger_unregister_simple(struct led_trigger *trig)
> {
> - if (trig)
> + if (trig) {
> led_trigger_unregister(trig);
> + kfree_const(trig->name);
> + }
> kfree(trig);
> }
> EXPORT_SYMBOL_GPL(led_trigger_unregister_simple);
> diff --git a/drivers/net/can/led.c b/drivers/net/can/led.c
> index c1b667675fa1..2d7d1b0d20f9 100644
> --- a/drivers/net/can/led.c
> +++ b/drivers/net/can/led.c
> @@ -115,13 +115,13 @@ static int can_led_notifier(struct notifier_block *nb, unsigned long msg,
>
> if (msg == NETDEV_CHANGENAME) {
> snprintf(name, sizeof(name), "%s-tx", netdev->name);
> - led_trigger_rename_static(name, priv->tx_led_trig);
> + led_trigger_rename(priv->tx_led_trig, name);
>
> snprintf(name, sizeof(name), "%s-rx", netdev->name);
> - led_trigger_rename_static(name, priv->rx_led_trig);
> + led_trigger_rename(priv->rx_led_trig, name);
>
> snprintf(name, sizeof(name), "%s-rxtx", netdev->name);
> - led_trigger_rename_static(name, priv->rxtx_led_trig);
> + led_trigger_rename(priv->rxtx_led_trig, name);
> }
>
> return NOTIFY_DONE;
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index b7e82550e655..e706c28bb35b 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -275,6 +275,8 @@ extern void led_trigger_unregister(struct led_trigger *trigger);
> extern int devm_led_trigger_register(struct device *dev,
> struct led_trigger *trigger);
>
> +extern int led_trigger_register_format(struct led_trigger **trigger,
> + const char *fmt, ...);
> extern void led_trigger_register_simple(const char *name,
> struct led_trigger **trigger);
> extern void led_trigger_unregister_simple(struct led_trigger *trigger);
> @@ -298,28 +300,25 @@ static inline void *led_get_trigger_data(struct led_classdev *led_cdev)
> }
>
> /**
> - * led_trigger_rename_static - rename a trigger
> - * @name: the new trigger name
> + * led_trigger_rename - rename a trigger
> * @trig: the LED trigger to rename
> + * @fmt: format string for new name
> *
> - * Change a LED trigger name by copying the string passed in
> - * name into current trigger name, which MUST be large
> - * enough for the new string.
> - *
> - * Note that name must NOT point to the same string used
> - * during LED registration, as that could lead to races.
> - *
> - * This is meant to be used on triggers with statically
> - * allocated name.
> + * rebaptize the given trigger.
> */
> -extern void led_trigger_rename_static(const char *name,
> - struct led_trigger *trig);
> +extern int led_trigger_rename(struct led_trigger *trig, const char *fmt, ...);
>
> #else
>
> /* Trigger has no members */
> struct led_trigger {};
>
> +static inline int led_trigger_register_format(struct led_trigger **trigger,
> + const char *fmt, ...)
> +{
> + return 0;
> +}
> +
> /* Trigger inline empty functions */
> static inline void led_trigger_register_simple(const char *name,
> struct led_trigger **trigger) {}
> @@ -342,6 +341,11 @@ static inline void *led_get_trigger_data(struct led_classdev *led_cdev)
> return NULL;
> }
>
> +static inline int led_trigger_rename(struct led_trigger *trig, const char *fmt, ...)
> +{
> + return 0;
> +}
> +
> #endif /* CONFIG_LEDS_TRIGGERS */
>
> /* Trigger specific functions */
>

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