diff --git a/kernel/kmod.c b/kernel/kmod.c
index 806a5ea69fa1764ae8dbceefb640b7af0bfe9d0c..0c46b82ac53e1a82623f0c2f8d959a13ffef67b4 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -8,6 +8,7 @@
#include <linux/kernel.h>
#include <linux/kthread.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/uaccess.h>
#include <linux/vmalloc.h>
@@ -15,7 +16,7 @@
#define CLASS_NAME "sibyl_class"
#define SLOTS 4
-#define SLOT_INTERVAL_NS 10000000
+#define SLOT_INTERVAL_NS 1000000000
#define MAX_MEASUREMENTS 16
@@ -43,10 +44,16 @@ static struct task_struct *timed_thread;
static DECLARE_WAIT_QUEUE_HEAD(wq);
static atomic_t wake_counter = ATOMIC_INIT(0);
+// Send Buffers
#define SEND_BUFFER_SIZE 4096
-static uint8_t send_buffer[SEND_BUFFER_SIZE];
-static size_t send_buffer_size = 0;
+static struct mutex send_buffer_mutex;
+
+static uint8_t *primary_send_buffer;
+static size_t primary_send_buffer_size = 0;
+
+static uint8_t *secondary_send_buffer;
+static size_t secondary_send_buffer_size = 0;
static int slot = 0;
@@ -55,7 +62,8 @@ static int device_open(struct inode *inode, struct file *file) { return 0; }
static int device_release(struct inode *inode, struct file *file) { return 0; }
static uint32_t calculate_crc32(const packet_t *packet) {
- uint32_t crc = crc32(0, (void *)&packet->data.sender_id, sizeof(uint8_t));
+ uint32_t crc = crc32(0, (void *)&packet->magic, sizeof(uint8_t));
+ crc = crc32(crc, (void *)&packet->data.sender_id, sizeof(uint8_t));
crc = crc32(crc, (void *)&packet->data.count, sizeof(uint8_t));
crc = crc32(crc, (void *)&packet->data.measurements,
sizeof(measurement_t) * packet->data.count);
@@ -65,24 +73,38 @@ static uint32_t calculate_crc32(const packet_t *packet) {
static void prepare_for_sending(void) {
packet->crc = calculate_crc32(packet);
- send_buffer[0] = packet->magic;
- send_buffer[1] = packet->data.sender_id;
- send_buffer[2] = packet->data.count;
+ secondary_send_buffer[0] = packet->magic;
+ secondary_send_buffer[1] = packet->data.sender_id;
+ secondary_send_buffer[2] = packet->data.count;
uint8_t *bytes = (uint8_t *)packet->data.measurements;
for (size_t i = 0; i < sizeof(measurement_t) * packet->data.count; i++) {
- send_buffer[3 + i] = bytes[i];
+ secondary_send_buffer[3 + i] = bytes[i];
}
bytes = (uint8_t *)&packet->crc;
for (size_t i = 0; i < sizeof(uint32_t); i++) {
- send_buffer[3 + sizeof(measurement_t) * packet->data.count + i] = bytes[i];
+ secondary_send_buffer[3 + sizeof(measurement_t) * packet->data.count + i] =
+ bytes[i];
}
- send_buffer_size =
+ secondary_send_buffer_size =
3 + sizeof(measurement_t) * packet->data.count + sizeof(uint32_t);
+
+ // Swap buffers
+ mutex_lock(&send_buffer_mutex);
+
+ uint8_t *tmp = primary_send_buffer;
+ primary_send_buffer = secondary_send_buffer;
+ secondary_send_buffer = tmp;
+
+ size_t tmp_size = primary_send_buffer_size;
+ primary_send_buffer_size = secondary_send_buffer_size;
+ secondary_send_buffer_size = tmp_size;
+
+ mutex_unlock(&send_buffer_mutex);
}
static ssize_t device_write(struct file *filp, const char *input, size_t length,
@@ -144,10 +166,17 @@ static inline void send_byte(uint8_t byte) {
send_bit(1);
}
-static void send_data(const packet_t *packet) {
- for (size_t i = 0; i < send_buffer_size; i++) {
- send_byte(send_buffer[i]);
+static void send_buffer(void) {
+ printk(KERN_INFO "Send %zu bytes\n", primary_send_buffer_size);
+
+ unsigned long flags;
+ local_irq_save(flags);
+
+ for (size_t i = 0; i < primary_send_buffer_size; i++) {
+ send_byte(primary_send_buffer[i]);
}
+
+ local_irq_restore(flags);
}
static int timed_thread_fn(void *args) {
@@ -156,7 +185,9 @@ static int timed_thread_fn(void *args) {
atomic_dec(&wake_counter);
if (slot == 0) {
- send_data(packet);
+ mutex_lock(&send_buffer_mutex);
+ send_buffer();
+ mutex_unlock(&send_buffer_mutex);
}
slot = (slot + 1) % SLOTS;
@@ -168,6 +199,9 @@ static int timed_thread_fn(void *args) {
static int __init lkm_init(void) {
dev_t dev;
+ mutex_init(&send_buffer_mutex);
+
+ // Allocate memory for packet
packet = (packet_t *)vmalloc(sizeof(packet_t));
if (packet == NULL) {
@@ -188,8 +222,27 @@ static int __init lkm_init(void) {
prepare_for_sending();
- // Dynamically allocate major number
+ // Allocate memory for send buffers
+ primary_send_buffer = (uint8_t *)vmalloc(SEND_BUFFER_SIZE);
+ primary_send_buffer_size = 0;
+ if (primary_send_buffer == NULL) {
+ vfree(packet->data.measurements);
+ vfree(packet);
+ return -EFAULT;
+ }
+
+ secondary_send_buffer = (uint8_t *)vmalloc(SEND_BUFFER_SIZE);
+ secondary_send_buffer_size = 0;
+ if (secondary_send_buffer == NULL) {
+ vfree(primary_send_buffer);
+ vfree(packet->data.measurements);
+ vfree(packet);
+ return -EFAULT;
+ }
+
if (alloc_chrdev_region(&dev, 0, 1, DEVICE_NAME) < 0) {
+ vfree(primary_send_buffer);
+ vfree(secondary_send_buffer);
vfree(packet->data.measurements);
vfree(packet);
printk(KERN_ALERT "Failed to allocate major number\n");
@@ -199,6 +252,8 @@ static int __init lkm_init(void) {
class = class_create(CLASS_NAME);
if (IS_ERR(class)) {
+ vfree(primary_send_buffer);
+ vfree(secondary_send_buffer);
vfree(packet->data.measurements);
vfree(packet);
unregister_chrdev_region(MKDEV(major_number, 0), 1);
@@ -208,6 +263,8 @@ static int __init lkm_init(void) {
if (device_create(class, NULL, MKDEV(major_number, 0), NULL, DEVICE_NAME) ==
NULL) {
+ vfree(primary_send_buffer);
+ vfree(secondary_send_buffer);
vfree(packet->data.measurements);
vfree(packet);
class_destroy(class);
@@ -218,6 +275,8 @@ static int __init lkm_init(void) {
cdev_init(&mycdev, &fops);
if (cdev_add(&mycdev, MKDEV(major_number, 0), 1) < 0) {
+ vfree(primary_send_buffer);
+ vfree(secondary_send_buffer);
vfree(packet->data.measurements);
vfree(packet);
device_destroy(class, MKDEV(major_number, 0));
@@ -230,6 +289,8 @@ static int __init lkm_init(void) {
printk(KERN_INFO "lkm: device created successfully\n");
if (gpio_request(GPIO_PIN, "GPIO_PIN") < 0) {
+ vfree(primary_send_buffer);
+ vfree(secondary_send_buffer);
vfree(packet->data.measurements);
vfree(packet);
cdev_del(&mycdev);
@@ -243,6 +304,8 @@ static int __init lkm_init(void) {
timed_thread = kthread_run(timed_thread_fn, NULL, "timed_thread");
if (IS_ERR(timed_thread)) {
+ vfree(primary_send_buffer);
+ vfree(secondary_send_buffer);
vfree(packet->data.measurements);
vfree(packet);
cdev_del(&mycdev);
@@ -262,6 +325,10 @@ static int __init lkm_init(void) {
}
static void __exit lkm_exit(void) {
+ mutex_destroy(&send_buffer_mutex);
+
+ vfree(primary_send_buffer);
+ vfree(secondary_send_buffer);
vfree(packet->data.measurements);
vfree(packet);
cdev_del(&mycdev);