Re: [PATCH v3] firmware loader: introduce module parameter tocustomize fw search path

[anish kumar]

On Sat, 2012-10-27 at 09:23 +0800, Ming Lei wrote:
> This patch introduces one module parameter of 'path' in firmware_class
> to support customizing firmware image search path, so that people can
> use its own firmware path if the default built-in paths can't meet their
> demand[1], and the typical usage is passing the below from kernel command
> parameter when 'firmware_class' is built in kernel:
> 
> 	firmware_class.path=$CUSTOMIZED_PATH
> 
> [1], https://lkml.org/lkml/2012/10/11/337
> 
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxxxxx>
> ---
> v3
> 	- fix one mistake on checking unset firmware path
> 
> v2
> 	- take a cleaner approach suggested by Linus
> 	- mark the path array as const because it needn't be changed
> 	- fix one error in Document about the module name
> 
> v1:
> 	- remove kernel boot parameter and only support the feature by
>         module parameter as suggested by Greg
> ---
>  Documentation/firmware_class/README |    5 +++++
>  drivers/base/firmware_class.c       |   17 ++++++++++++++++-
>  2 files changed, 21 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/firmware_class/README b/Documentation/firmware_class/README
> index 815b711..e9fce78 100644
> --- a/Documentation/firmware_class/README
> +++ b/Documentation/firmware_class/README
> @@ -22,12 +22,17 @@
>  	- calls request_firmware(&fw_entry, $FIRMWARE, device)
>  	- kernel searchs the fimware image with name $FIRMWARE directly
>  	in the below search path of root filesystem:
> +		User customized search path by module parameter 'path'[1]
>  		"/lib/firmware/updates/" UTS_RELEASE,
>  		"/lib/firmware/updates",
>  		"/lib/firmware/" UTS_RELEASE,
>  		"/lib/firmware"
>  	- If found, goto 7), else goto 2)
>  
> +	[1], the 'path' is a string parameter which length should be less
whose length should be less...
> +	than 256, user should pass 'firmware_class.path=$CUSTOMIZED_PATH'
> +	if firmware_class is built in kernel(the general situation)
> +
>   2), userspace:
>   	- /sys/class/firmware/xxx/{loading,data} appear.
>  	- hotplug gets called with a firmware identifier in $FIRMWARE
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index 8945f4e..62568c2 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -267,13 +267,23 @@ static void fw_free_buf(struct firmware_buf *buf)
>  }
>  
>  /* direct firmware loading support */
> -static const char *fw_path[] = {
> +static char fw_path_para[256];
> +static const char * const fw_path[] = {
> +	fw_path_para,
>  	"/lib/firmware/updates/" UTS_RELEASE,
>  	"/lib/firmware/updates",
>  	"/lib/firmware/" UTS_RELEASE,
>  	"/lib/firmware"
>  };
>  
> +/*
> + * Typical usage is that passing 'firmware_class.path=$CUSTOMIZED_PATH'
> + * from kernel command because firmware_class is generally built in
do you mean kernel command line?
> + * kernel instead of module.
> + */
> +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");
> +
>  /* Don't inline this: 'struct kstat' is biggish */
>  static noinline long fw_file_size(struct file *file)
>  {
> @@ -315,6 +325,11 @@ static bool fw_get_filesystem_firmware(struct firmware_buf *buf)
>  
>  	for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
>  		struct file *file;
> +
> +		/* skip the unset customized path */
> +		if (!fw_path[i][0])
> +			continue;
> +
>  		snprintf(path, PATH_MAX, "%s/%s", fw_path[i], buf->fw_id);
>  
>  		file = filp_open(path, O_RDONLY, 0);


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