usb: gadget: printer: Remove pnp_string static buffer

pnp string is usually much shorter than 1k so let's stop wasting 1k of
memory for its buffer and make it dynamically alocated.
This also removes 1k len limitation for pnp_string and
adds a new line after string content if required.

Signed-off-by: Krzysztof Opasiak <[e-mail]>
Signed-off-by: Felipe Balbi <[e-mail]>

drivers/usb/gadget/function/f_printer.c

···
 
 #include "u_printer.h"
 
-#define PNP_STRING_LEN		1024
 #define PRINTER_MINORS		4
 #define GET_DEVICE_ID		0
 #define GET_PORT_STATUS		1
···
 	switch (ctrl->bRequest) {
 	case GET_DEVICE_ID:
 		w_index >>= 8;
-		if (w_length <= PNP_STRING_LEN &&
-		    (USB_DIR_IN & ctrl->bRequestType))
+		if (USB_DIR_IN & ctrl->bRequestType)
 			break;
 		return false;
 	case GET_PORT_STATUS:
···
 	struct printer_dev *dev = func_to_printer(f);
 	struct usb_composite_dev *cdev = f->config->cdev;
 	struct usb_request	*req = cdev->req;
+	u8			*buf = req->buf;
 	int			value = -EOPNOTSUPP;
 	u16			wIndex = le16_to_cpu(ctrl->wIndex);
 	u16			wValue = le16_to_cpu(ctrl->wValue);
···
 			if ((wIndex>>8) != dev->interface)
 				break;
 
-			value = (dev->pnp_string[0] << 8) | dev->pnp_string[1];
-			memcpy(req->buf, dev->pnp_string, value);
+			if (!dev->pnp_string) {
+				value = 0;
+				break;
+			}
+			value = strlen(dev->pnp_string);
+			buf[0] = (value >> 8) & 0xFF;
+			buf[1] = value & 0xFF;
+			memcpy(buf + 2, dev->pnp_string, value);
 			DBG(dev, "1284 PNP String: %x %s\n", value,
-					&dev->pnp_string[2]);
+			    dev->pnp_string);
 			break;
 
 		case GET_PORT_STATUS: /* Get Port Status */
···
 			if (wIndex != dev->interface)
 				break;
 
-			*(u8 *)req->buf = dev->printer_status;
+			buf[0] = dev->printer_status;
 			value = min_t(u16, wLength, 1);
 			break;
 
···
 					      char *page)
 {
 	struct f_printer_opts *opts = to_f_printer_opts(item);
-	int result;
+	int result = 0;
 
 	mutex_lock(&opts->lock);
-	result = strlcpy(page, opts->pnp_string + 2, PNP_STRING_LEN - 2);
+	if (!opts->pnp_string)
+		goto unlock;
+
+	result = strlcpy(page, opts->pnp_string, PAGE_SIZE);
+	if (result >= PAGE_SIZE) {
+		result = PAGE_SIZE;
+	} else if (page[result - 1] != '\n' && result + 1 < PAGE_SIZE) {
+		page[result++] = '\n';
+		page[result] = '\0';
+	}
+
+unlock:
 	mutex_unlock(&opts->lock);
 
 	return result;
···
 					       const char *page, size_t len)
 {
 	struct f_printer_opts *opts = to_f_printer_opts(item);
-	int result, l;
+	char *new_pnp;
+	int result;
 
 	mutex_lock(&opts->lock);
-	result = strlcpy(opts->pnp_string + 2, page, PNP_STRING_LEN - 2);
-	l = strlen(opts->pnp_string + 2) + 2;
-	opts->pnp_string[0] = (l >> 8) & 0xFF;
-	opts->pnp_string[1] = l & 0xFF;
+
+	new_pnp = kstrndup(page, len, GFP_KERNEL);
+	if (!new_pnp) {
+		result = -ENOMEM;
+		goto unlock;
+	}
+
+	if (opts->pnp_string_allocated)
+		kfree(opts->pnp_string);
+
+	opts->pnp_string_allocated = true;
+	opts->pnp_string = new_pnp;
+	result = len;
+unlock:
 	mutex_unlock(&opts->lock);
 
 	return result;
···
 
 	mutex_unlock(&printer_ida_lock);
 
+	if (opts->pnp_string_allocated)
+		kfree(opts->pnp_string);
 	kfree(opts);
 }
 

drivers/usb/gadget/function/u_printer.h

···
 
 #include <linux/usb/composite.h>
 
-#define PNP_STRING_LEN			1024
-
 struct f_printer_opts {
 	struct usb_function_instance	func_inst;
 	int				minor;
-	char				pnp_string[PNP_STRING_LEN];
+	char				*pnp_string;
+	bool				pnp_string_allocated;
 	unsigned			q_len;
 
 	/*

drivers/usb/gadget/legacy/printer.c

···
 
 static char				product_desc [40] = DRIVER_DESC;
 static char				serial_num [40] = "1";
-static char				pnp_string[PNP_STRING_LEN] =
-	"XXMFG:linux;MDL:g_printer;CLS:PRINTER;SN:1;";
+static char				*pnp_string =
+	"MFG:linux;MDL:g_printer;CLS:PRINTER;SN:1;";
 
 /* static strings, in UTF-8 */
 static struct usb_string		strings [] = {
···
 static int printer_bind(struct usb_composite_dev *cdev)
 {
 	struct f_printer_opts *opts;
-	int ret, len;
+	int ret;
 
 	fi_printer = usb_get_function_instance("printer");
 	if (IS_ERR(fi_printer))
 		return PTR_ERR(fi_printer);
 
-	if (iPNPstring)
-		strlcpy(&pnp_string[2], iPNPstring, PNP_STRING_LEN - 2);
-
-	len = strlen(pnp_string);
-	pnp_string[0] = (len >> 8) & 0xFF;
-	pnp_string[1] = len & 0xFF;
-
 	opts = container_of(fi_printer, struct f_printer_opts, func_inst);
 	opts->minor = 0;
-	memcpy(opts->pnp_string, pnp_string, PNP_STRING_LEN);
 	opts->q_len = QLEN;
+	if (iPNPstring) {
+		opts->pnp_string = kstrdup(iPNPstring, GFP_KERNEL);
+		if (!opts->pnp_string) {
+			ret = -ENOMEM;
+			goto fail_put_func_inst;
+		}
+		opts->pnp_string_allocated = true;
+		/*
+		 * we don't free this memory in case of error
+		 * as printer cleanup func will do this for us
+		 */
+	} else {
+		opts->pnp_string = pnp_string;
+	}
 
 	ret = usb_string_ids_tab(cdev, strings);
 	if (ret < 0)