[PATCH] Fix USB printer transfers

From Barry K. Nathan

This fixes the ulblp transfer length code, which would otherwise skip
the final iteration and lead to incomplete printer output (and us
waiting forever for the transfer to complete)

drivers/usb/class/usblp.c

@@ -603,7 +603,7 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 {
 	DECLARE_WAITQUEUE(wait, current);
 	struct usblp *usblp = file->private_data;
-	int timeout, err = 0, transfer_length;
+	int timeout, err = 0, transfer_length = 0;
 	size_t writecount = 0;
 
 	while (writecount < count) {
@@ -654,6 +654,16 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 			continue;
 		}
 
+		/* We must increment writecount here, and not at the
+		 * end of the loop. Otherwise, the final loop iteration may
+		 * be skipped, leading to incomplete printer output.
+		 */
+		writecount += transfer_length;
+		if (writecount == count) {
+			up(&usblp->sem);
+			break;
+		}
+
 		transfer_length=(count - writecount);
 		if (transfer_length > USBLP_BUF_SIZE)
 			transfer_length = USBLP_BUF_SIZE;
@@ -677,8 +687,6 @@ static ssize_t usblp_write(struct file *file, const char __user *buffer, size_t
 			break;
 		}
 		up (&usblp->sem);
-
-		writecount += transfer_length;
 	}
 
 	return count;