linux-kernel - Re: [PATCH v2.5 2/3] firmware: Add support for loading compressed files

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Message-ID: <20190619232646.GE19023@42.do-not-panic.com>
Date:   Wed, 19 Jun 2019 23:26:47 +0000
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Shuah Khan <shuah@...nel.org>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v2.5 2/3] firmware: Add support for loading compressed
 files

Sorry for the late review... Ah!

On Tue, Jun 11, 2019 at 02:26:25PM +0200, Takashi Iwai wrote:
> @@ -354,7 +454,12 @@ module_param_string(path, fw_path_para, sizeof(fw_path_para), 0644);
>  MODULE_PARM_DESC(path, "customized firmware image search path with a higher priority than default path");
>  
>  static int
> -fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv)
> +fw_get_filesystem_firmware(struct device *device, struct fw_priv *fw_priv,
> +			   const char *suffix,
> +			   int (*decompress)(struct device *dev,
> +					     struct fw_priv *fw_priv,
> +					     size_t in_size,
> +					     const void *in_buffer))

I *think* this could be cleaner, I'll elaborate below.

> @@ -645,7 +768,13 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
>  	if (ret <= 0) /* error or already assigned */
>  		goto out;
>  
> -	ret = fw_get_filesystem_firmware(device, fw->priv);
> +	ret = fw_get_filesystem_firmware(device, fw->priv, "", NULL);
> +#ifdef CONFIG_FW_LOADER_COMPRESS
> +	if (ret == -ENOENT)
> +		ret = fw_get_filesystem_firmware(device, fw->priv, ".xz",
> +						 fw_decompress_xz);
> +#endif

Hrm, and let more #ifdef'ery.

And so if someone wants to add bzip, we'd add yet-another if else on the
return value of this call... and yet more #ifdefs.

We already have a list of paths supported. It seems what we need instead
is a list of supported suffixes, and a respective structure which then
has its set of callbacks for posthandling.

This way, this could all be handled inside fw_get_filesystem_firmware()
neatly, and we can just strive towards avoiding #ifdef'ery.

Since I'm late to review, this could be done in the future, but I do
think something along these lines would make the code more maintainable
and extensible.

  Luis