From: Thadeu Lima de Souza Cascardo <cascardo@holoscopio.com>
Date: Tue, 8 Dec 2009 17:57:33 +0000 (-0200)
Subject: Allocate buffers for any number of devices.
X-Git-Url: http://git.cascardo.eti.br/?p=cascardo%2Fkernel%2Fsamples%2F02.char%2F.git;a=commitdiff_plain;h=039521d8d6979c17201080e1349aef039ed1c91a

Allocate buffers for any number of devices.
---

diff --git a/helloc.c b/helloc.c
index 00ce97d..f43a767 100644
--- a/helloc.c
+++ b/helloc.c
@@ -13,37 +13,29 @@ MODULE_DESCRIPTION("A hello world char device");
 MODULE_VERSION("1.0.0");
 
 #define BUFFER_SIZE 4096
-
-/* Message buffer we send to upstream */
-static char *hello_message;
-static char *goodbye_message;
+#define DEVICE_NUMBER 2
 
 struct message {
 	char *text;
 	size_t len;
 };
 
+/* Message buffer we send to upstream */
+static struct message *hello_message[DEVICE_NUMBER];
+
 static int helloc_open(struct inode *ino, struct file *filp)
 {
 	struct message *msg;
 	printk(KERN_INFO "Opened file with minor %d\n", iminor(ino));
-	msg = kmalloc(sizeof(struct message), GFP_KERNEL);
-	if (!msg)
-		return -ENOMEM;
-	if (iminor(ino) == 0) {
-		msg->text = hello_message;
-		msg->len = BUFFER_SIZE;
-	} else {
-		msg->text = goodbye_message;
-		msg->len = BUFFER_SIZE;
-	}
+	if (iminor(ino) >= DEVICE_NUMBER)
+		return -ENODEV;
+	msg = hello_message[iminor(ino)];
 	filp->private_data = msg;
 	return 0;
 }
 
 static int helloc_release(struct inode *ino, struct file *filp)
 {
-	kfree(filp->private_data);
 	return 0;
 }
 
@@ -103,17 +95,45 @@ static struct file_operations helloc_fops = {
 static dev_t dev;
 static struct cdev *cdev;
 
+static void helloc_free(void)
+{
+	int i;
+	for (i = 0; i < DEVICE_NUMBER; i++) {
+		if (hello_message[i])
+			kfree(hello_message[i]->text);
+		kfree(hello_message[i]);
+	}
+}
+
+static int __init helloc_alloc(void)
+{
+	int i;
+	for (i = 0; i < DEVICE_NUMBER; i++) {
+		hello_message[i] = kzalloc(sizeof(struct message), GFP_KERNEL);
+		if (!hello_message[i])
+			goto out;
+		hello_message[i]->text = kzalloc(BUFFER_SIZE, GFP_KERNEL);
+		if (!hello_message[i]->text)
+			goto out;
+	}
+	return 0;
+out:
+	for (; i >= 0; i--) {
+		if (hello_message[i])
+			kfree(hello_message[i]->text);
+		kfree(hello_message[i]);
+	}
+	return -ENOMEM;
+}
+
 static int __init helloc_init(void)
 {
-	int r = -ENOMEM;
+	int r;
+	r = helloc_alloc();
+	if (r)
+		goto out_alloc2;
 	/* allocate any major number with only one minor */
-	hello_message = kzalloc(BUFFER_SIZE, GFP_KERNEL);
-	if (!hello_message)
-		goto out_hello;
-	goodbye_message = kzalloc(BUFFER_SIZE, GFP_KERNEL);
-	if (!goodbye_message)
-		goto out_goodbye;
-	r = alloc_chrdev_region(&dev, 0, 2, "helloc");
+	r = alloc_chrdev_region(&dev, 0, DEVICE_NUMBER, "helloc");
 	if (r)
 		goto out_region;
 	r = -ENOMEM;
@@ -127,7 +147,7 @@ static int __init helloc_init(void)
 	cdev->owner = THIS_MODULE;
 	cdev->ops = &helloc_fops;
 	/* register the chardev to the system */
-	r = cdev_add(cdev, dev, 2);
+	r = cdev_add(cdev, dev, DEVICE_NUMBER);
 	if (r)
 		goto out_add;
 	return 0;
@@ -136,12 +156,9 @@ out_add:
 	kfree(cdev);
 out_alloc:
 	/* release the device number allocated */
-	unregister_chrdev_region(dev, 2);
+	unregister_chrdev_region(dev, DEVICE_NUMBER);
 out_region:
-	kfree(goodbye_message);
-out_goodbye:
-	kfree(hello_message);
-out_hello:
+out_alloc2:
 	return r;
 }
 
@@ -150,9 +167,8 @@ static void __exit helloc_exit(void)
 	/* remove the chardev from the system */
 	cdev_del(cdev);
 	/* release the device number allocated */
-	unregister_chrdev_region(dev, 2);
-	kfree(goodbye_message);
-	kfree(hello_message);
+	unregister_chrdev_region(dev, DEVICE_NUMBER);
+	helloc_free();
 }
 
 module_init(helloc_init);