Re: [PATCH 3/3] firmware loader: allow distribution to choose default search paths

[Takashi Iwai <tiwai@suse.de>]

At Wed, 5 Jun 2013 18:28:46 +0800,
Ming Lei wrote:
> 
> Hi,
> 
> On Wed, Jun 5, 2013 at 5:35 PM, Ming Lei <ming.lei@canonical.com> wrote:
> >
> > Looks we can let fw_get_fw_file_from_paths() handle all
> > predefined paths(CONFIG_FW_CUSTOMIZED_PATH and
> > kernel built-in paths), then fw_get_filesystem_firmware()
> > may become simple, just check fw_path_para and all
> > other paths by fw_get_fw_file_from_paths(). How about the
> > idea?
> 
> So follows the revised patch for review, which should be cleaner
> than before, :-)

Hmm, separating with semicolons isn't so common, but we can live with
it.  I thought the previous loop can be kept but just pass each member
to fw_get_file_firmware() unconditionally.  This will reduce the
changes, I guess.  But it's just a matter of taste, here is no
critically hot path, after all.

> 
> Any comments?
> 
> ---
>  drivers/base/Kconfig          |   14 +++++++
>  drivers/base/firmware_class.c |   87 +++++++++++++++++++++++++++++------------
>  2 files changed, 76 insertions(+), 25 deletions(-)
> 
> diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig
> index 07abd9d..b66e63e 100644
> --- a/drivers/base/Kconfig
> +++ b/drivers/base/Kconfig
> @@ -156,6 +156,20 @@ config FW_LOADER_USER_HELPER
>  	  no longer required unless you have a special firmware file that
>  	  resides in a non-standard path.
> 
> +config FW_CUSTOMIZED_PATH
> +	string "default firmware search paths for direct loading"
> +	help
> +	  On some distribution(e.g. android), firmware images aren't
> +	  put under kernel built-in search paths, so provide this option
> +	  for distributions to choose a distribution specific firmware
> +	  search path. The option allows to choose more than one path,
> +	  and paths are seperated with semicolon(e.g. on android, the
> +	  option might look as "/etc/firmware;/vendor/firmware"). Each
> +	  path should be a absolute path, and relative path will be
> +	  ignored.
> +
> +	  If you are unsure about this, don't choose here.
> +
>  config DEBUG_DRIVER
>  	bool "Driver Core verbose debug messages"
>  	depends on DEBUG_KERNEL
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index c743409..218dc1b 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -265,13 +265,14 @@ static void fw_free_buf(struct firmware_buf *buf)
> 
>  /* direct firmware loading support */
>  static char fw_path_para[256];
> -static const char * const fw_path[] = {
> -	fw_path_para,
> -	"/lib/firmware/updates/" UTS_RELEASE,
> -	"/lib/firmware/updates",
> -	"/lib/firmware/" UTS_RELEASE,
> -	"/lib/firmware"
> -};
> +static const char * const fw_paths =
> +#ifdef CONFIG_FW_CUSTOMIZED_PATH
> +	CONFIG_FW_CUSTOMIZED_PATH ";"
> +#endif
> +	"/lib/firmware/updates/" UTS_RELEASE ";"
> +	"/lib/firmware/updates;"
> +	"/lib/firmware/" UTS_RELEASE ";"
> +	"/lib/firmware";
> 
>  /*
>   * Typical usage is that passing 'firmware_class.path=$CUSTOMIZED_PATH'
> @@ -314,30 +315,66 @@ static bool fw_read_file_contents(struct file
> *file, struct firmware_buf *fw_buf
>  	return true;
>  }
> 
> -static bool fw_get_filesystem_firmware(struct device *device,
> -				       struct firmware_buf *buf)
> +static bool fw_get_file_firmware(const char *path,
> +				 struct firmware_buf *buf)
>  {
> -	int i;
> -	bool success = false;
> -	char *path = __getname();
> +	struct file *file;
> +	bool success;
> +
> +	file = filp_open(path, O_RDONLY, 0);
> +	if (IS_ERR(file))
> +		return false;
> +	success = fw_read_file_contents(file, buf);
> +	fput(file);
> 
> -	for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
> -		struct file *file;
> +	return success;
> +}
> 
> -		/* skip the unset customized path */
> -		if (!fw_path[i][0])
> -			continue;
> +/* The path in @paths is seperated by ';' */
> +static bool fw_get_fw_file_from_paths(const char *paths, char *path,
> +				      struct firmware_buf *buf)
> +{
> +	int len, start, end = -1;
> +	char *pos;
> +
> +	if (!paths[0])
> +		return false;
> 
> -		snprintf(path, PATH_MAX, "%s/%s", fw_path[i], buf->fw_id);
> +	do {
> +		start = end + 1;
> +		pos = strchr(&paths[start], ';');
> +		if (pos) {
> +			end = (int)(pos - paths);
> +			len = end - start;
> +		} else {
> +			len = strlen(&paths[start]);
> +		}
> 
> -		file = filp_open(path, O_RDONLY, 0);
> -		if (IS_ERR(file))
> +		if (len <= 0 || PATH_MAX < len + strlen(buf->fw_id))
>  			continue;
> -		success = fw_read_file_contents(file, buf);
> -		fput(file);
> -		if (success)
> -			break;
> -	}
> +		strncpy(path, &paths[start], len);
> +		snprintf(&path[len], PATH_MAX - len, "/%s", buf->fw_id);
> +		/* don't search relative path */
> +		if (strstr(path, ".."))
> +			continue;

I expect you'll prepare this path sanity check part in a separate
patch, right?  It's basically independent from the new kconfig.


thanks,

Takashi


> +
> +		if (fw_get_file_firmware(path, buf))
> +			return true;
> +	} while (pos && end < strlen(paths) - 1);
> +
> +	return false;
> +}
> +
> +static bool fw_get_filesystem_firmware(struct device *device,
> +				       struct firmware_buf *buf)
> +{
> +	bool success = false;
> +	char *path = __getname();
> +
> +	/* search runtime paths first, then static pre-defined paths */
> +	success = fw_get_fw_file_from_paths(fw_path_para, path, buf);
> +	if (!success)
> +		success = fw_get_fw_file_from_paths(fw_paths, path, buf);
>  	__putname(path);
> 
>  	if (success) {
> -- 
> 1.7.9.5
> 
> 
> Thanks,
> --
> Ming Lei
>