linux-kernel - Re: [PATCH v2 RESEND] leds: add led_trigger

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Message-ID: <CAK5ve-Jn_1Lc=FyX24_DHDz6+=VUC5xoiH4zUWLgRB=rgOiueA@mail.gmail.com>
Date:	Tue, 13 Nov 2012 16:33:14 -0800
From:	Bryan Wu <cooloney@...il.com>
To:	Fabio Baltieri <fabio.baltieri@...il.com>
Cc:	linux-leds@...r.kernel.org, linux-kernel@...r.kernel.org,
	Richard Purdie <rpurdie@...ys.net>,
	Kurt Van Dijck <kurt.van.dijck@....be>
Subject: Re: [PATCH v2 RESEND] leds: add led_trigger_rename function

On Sun, Nov 4, 2012 at 1:54 AM, Fabio Baltieri <fabio.baltieri@...il.com> wrote:
> Implements a "led_trigger_rename" function to rename a trigger with
> proper locking.
>
> This assumes that led name was originally allocated in non-constant
> storage.
>
> Signed-off-by: Fabio Baltieri <fabio.baltieri@...il.com>
> Cc: Kurt Van Dijck <kurt.van.dijck@....be>
> Cc: Bryan Wu <cooloney@...il.com>
> ---
>
> Hi Bryan,
>
> I'm resending this one as it was probably lost it in the mail transition.
>
> Fabio
>
>  drivers/leds/led-triggers.c | 13 +++++++++++++
>  include/linux/leds.h        | 18 ++++++++++++++++++
>  2 files changed, 31 insertions(+)
>
> diff --git a/drivers/leds/led-triggers.c b/drivers/leds/led-triggers.c
> index 262eb41..a4fa4bf 100644
> --- a/drivers/leds/led-triggers.c
> +++ b/drivers/leds/led-triggers.c
> @@ -166,6 +166,19 @@ 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)
> +{
> +       /* new name must be on a temporary string to prevent races */
> +       BUG_ON(name == trig->name);
> +
> +       down_write(&triggers_list_lock);
> +       /* this assumes that trig->name was originaly allocated to
> +        * non constant storage */
> +       strcpy((char *)trig->name, name);

Is this strcpy() safe here? Probably strncpy() or strlcpy() is safer.

> +       up_write(&triggers_list_lock);
> +}
> +EXPORT_SYMBOL_GPL(led_trigger_rename_static);
> +
>  /* LED Trigger Interface */
>
>  int led_trigger_register(struct led_trigger *trig)
> diff --git a/include/linux/leds.h b/include/linux/leds.h
> index 6e53bb3..8107592 100644
> --- a/include/linux/leds.h
> +++ b/include/linux/leds.h
> @@ -139,6 +139,24 @@ extern void led_blink_set_oneshot(struct led_classdev *led_cdev,
>  extern void led_set_brightness(struct led_classdev *led_cdev,
>                                enum led_brightness brightness);
>
> +/**
> + * led_trigger_rename_static - rename a trigger
> + * @name: the new trigger name
> + * @trig: the LED trigger to rename
> + *
> + * 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.
> + */
> +extern void led_trigger_rename_static(const char *name,
> +                                     struct led_trigger *trig);
> +

Any example how to use this new API?

Thanks,
-Bryan

>  /*
>   * LED Triggers
>   */
> --
> 1.7.12.1
>
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