Re: [PATCH 2/2] media: rc: improve lirc module detection

[Mauro Carvalho Chehab <mchehab@osg.samsung.com>]

Em Sat, 21 Nov 2015 16:30:56 +0100
Heiner Kallweit <hkallweit1@gmail.com> escreveu:

> Improve detection whether lirc codec is loaded and avoid dependency
> on config symbols and having to check for a specific module.
> 
> This also fixes the bug that the current check checks for module
> lirc_dev instead of ir_lirc_codec (which depends on lirc_dev).
> If the ir_lirc_codec module is unloaded the check would still
> return OK.
> 
> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
> ---
>  drivers/media/rc/ir-lirc-codec.c |  4 ++++
>  drivers/media/rc/rc-main.c       | 19 +++++--------------
>  2 files changed, 9 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/media/rc/ir-lirc-codec.c b/drivers/media/rc/ir-lirc-codec.c
> index a32659f..7fc5b3f 100644
> --- a/drivers/media/rc/ir-lirc-codec.c
> +++ b/drivers/media/rc/ir-lirc-codec.c
> @@ -22,6 +22,8 @@
>  
>  #define LIRCBUF_SIZE 256
>  
> +extern atomic_t ir_raw_lirc_available;
> +

No, this is not good, due to several reasons:

- it lacks an EXPORT_SYMBOL_GPL(ir_raw_lirc_available);
- if lirc module is not compiled, the RC core will have a missed
  symbol.

The right thing to do is to have a var inside the RC core and a
way for LIRC to tell the core that it was loaded.

I would prefer to not export a var. So, perhaps this could be
done by calling some function.

Anyway, the way the patch is, it will break compilation, depending
on the config options.

Regards,
Mauro


>  /**
>   * ir_lirc_decode() - Send raw IR data to lirc_dev to be relayed to the
>   *		      lircd userspace daemon for decoding.
> @@ -398,6 +400,7 @@ static int ir_lirc_register(struct rc_dev *dev)
>  
>  	dev->raw->lirc.drv = drv;
>  	dev->raw->lirc.dev = dev;
> +	atomic_set(&ir_raw_lirc_available, 1);
>  	return 0;
>  
>  lirc_register_failed:
> @@ -413,6 +416,7 @@ static int ir_lirc_unregister(struct rc_dev *dev)
>  {
>  	struct lirc_codec *lirc = &dev->raw->lirc;
>  
> +	atomic_set(&ir_raw_lirc_available, 0);
>  	lirc_unregister_driver(lirc->drv->minor);
>  	lirc_buffer_free(lirc->drv->rbuf);
>  	kfree(lirc->drv);
> diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
> index 1042fa3..0bd11b4 100644
> --- a/drivers/media/rc/rc-main.c
> +++ b/drivers/media/rc/rc-main.c
> @@ -829,21 +829,12 @@ struct rc_filter_attribute {
>  		.mask = (_mask),					\
>  	}
>  
> -static bool lirc_is_present(void)
> +atomic_t ir_raw_lirc_available = ATOMIC_INIT(0);
> +EXPORT_SYMBOL(ir_raw_lirc_available);
> +
> +static inline bool lirc_is_present(void)
>  {
> -#if defined(CONFIG_LIRC_MODULE)
> -	struct module *lirc;
> -
> -	mutex_lock(&module_mutex);
> -	lirc = find_module("lirc_dev");
> -	mutex_unlock(&module_mutex);
> -
> -	return lirc ? true : false;
> -#elif defined(CONFIG_LIRC)
> -	return true;
> -#else
> -	return false;
> -#endif
> +	return atomic_read(&ir_raw_lirc_available) != 0;
>  }
>  
>  /**