Re: [RFC 1/2] firmware class: Add stream_firmware API.

[matthew . gerlach]

On Thu, 9 Mar 2017, yi1.li@xxxxxxxxxxxxxxx wrote:

> From: Yi Li <yi1.li@xxxxxxxxxxxxxxx>


Hi Yi,

Just one question below.

Matthew Gerlach


> Add function to load firmware in multiple chucks instead of
>
> loading the whole big firmware file at once.
>
> Signed-off-by: Yi Li <yi1.li@xxxxxxxxxxxxxxx>
> ---
> drivers/base/firmware_class.c | 128 ++++++++++++++++++++++++++++++++++++++++++
> include/linux/firmware.h      |   2 +
> 2 files changed, 130 insertions(+)
>
> diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
> index ac350c5..44fddff 100644
> --- a/drivers/base/firmware_class.c
> +++ b/drivers/base/firmware_class.c
> @@ -436,6 +436,62 @@ fw_get_filesystem_firmware(struct device *device, struct firmware_buf *buf)
> 	return rc;
> }
>
> +static int
> +fw_stream_filesystem_firmware(struct device *device, struct firmware_buf *buf,
> +			size_t offset, size_t length)
> +{
> +	int i, len;
> +	char *path;
> +	int rc = 0;
> +	struct file *file;
> +
> +	buf->size = 0;
> +
> +	path = __getname();
> +	if (!path)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < ARRAY_SIZE(fw_path); i++) {
> +		/* skip the unset customized path */
> +		if (!fw_path[i][0])
> +			continue;
> +
> +		len = snprintf(path, PATH_MAX, "%s/%s",
> +			       fw_path[i], buf->fw_id);

I'm probably being paranoid, but is it safe to assume the length of the 
buffer returned by __getname() is at least PATH_MAX?  It seems like
the length should be pagesize.

> +		if (len >= PATH_MAX) {
> +			rc = -ENAMETOOLONG;
> +			break;
> +		}
> +
> +		if (!path || !*path)
> +			continue;
> +
> +		if (!buf->data) {
> +			buf->data = vmalloc(length);
> +			if (!buf->data) {
> +				rc = -ENOMEM;
> +				break;
> +			}
> +		}
> +
> +		file = filp_open(path, O_RDONLY, 0);
> +		if (IS_ERR(file))
> +			continue;
> +
> +		buf->size = kernel_read(file, offset, (char *) buf->data,
> +					length);
> +		fput(file);
> +		break;
> +	}
> +
> +	__putname(path);
> +
> +	if (rc)
> +		dev_err(device, "loading %s failed with error %d\n",
> +			 path, rc);
> +	return rc;
> +}
> +
> /* firmware holds the ownership of pages */
> static void firmware_free_data(const struct firmware *fw)
> {
> @@ -1267,6 +1323,78 @@ request_firmware(const struct firmware **firmware_p, const char *name,
> }
> EXPORT_SYMBOL(request_firmware);
>
> +static int
> +_stream_firmware(const struct firmware **firmware_p, const char *name,
> +		  struct device *device, void *buf, size_t size,
> +		  unsigned int opt_flags, size_t offset, size_t length)
> +{
> +	int ret;
> +	struct firmware *fw = NULL;
> +	struct firmware_buf *fbuf;
> +
> +	if ((!firmware_p) || (!name || name[0] == '\0')) {
> +		dev_err(device, "invalid firmware pointer or file name\n");
> +		return -EINVAL;
> +	}
> +
> +	if (!*firmware_p) {
> +		ret = _request_firmware_prepare(&fw, name, device, buf, size);
> +		if (ret <= 0) {
> +			dev_err(device, "%s: _request_firmware_prepare failed %d\n",
> +				__func__, ret);
> +		}
> +	} else {
> +		fw = (struct firmware *) *firmware_p;
> +	}
> +
> +	fbuf = (struct firmware_buf *) fw->priv;
> +	ret = fw_stream_filesystem_firmware(device, fbuf, offset, length);
> +	fw->size = fbuf->size;
> +	fw->data = fbuf->data;
> +	*firmware_p = fw;
> +
> +	if (ret)
> +		dev_err(device, "streaming with error %d\n", ret);
> +	return ret;
> +}
> +
> +/**
> + * stream_firmware: - send firmware request and wait for it
> + * @firmware_p: pointer to firmware image
> + * @name: name of firmware file
> + * @device: device for which firmware is being loaded
> + * @offset: offset of the file to read from
> + * @length: length in bytes to read
> + *
> + *      @firmware_p will be used to return a firmware image by the name
> + *      of @name for device @device.
> + *
> + *      Should be called from user context where sleeping is allowed.
> + *
> + *      @name will be used as $FIRMWARE in the uevent environment and
> + *      should be distinctive enough not to be confused with any other
> + *      firmware image for this or any other device.
> + *
> + *	Caller must hold the reference count of @device.
> + *
> + *	The function can be called safely inside device's suspend and
> + *	resume callback.
> + **/
> +int
> +stream_firmware(const struct firmware **firmware_p, const char *name,
> +		 struct device *device, size_t offset, size_t length)
> +{
> +	size_t ret;
> +
> +	/* Need to pin this module until return */
> +	__module_get(THIS_MODULE);
> +	ret = _stream_firmware(firmware_p, name, device, NULL, 0,
> +				FW_OPT_UEVENT | FW_OPT_NO_WARN, offset, length);
> +	module_put(THIS_MODULE);
> +	return ret;
> +}
> +EXPORT_SYMBOL(stream_firmware);
> +
> /**
>  * request_firmware_direct: - load firmware directly without usermode helper
>  * @firmware_p: pointer to firmware image
> diff --git a/include/linux/firmware.h b/include/linux/firmware.h
> index b1f9f0c..accd7f6 100644
> --- a/include/linux/firmware.h
> +++ b/include/linux/firmware.h
> @@ -41,6 +41,8 @@ struct builtin_fw {
> #if defined(CONFIG_FW_LOADER) || (defined(CONFIG_FW_LOADER_MODULE) && defined(MODULE))
> int request_firmware(const struct firmware **fw, const char *name,
> 		     struct device *device);
> +int stream_firmware(const struct firmware **fw, const char *name,
> +		    struct device *device, size_t offset, size_t length);
> int request_firmware_nowait(
> 	struct module *module, bool uevent,
> 	const char *name, struct device *device, gfp_t gfp, void *context,
> --
> 2.7.4
>
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