Segmentation fault

[Averean]

I'm new to zephyr and to practice im trying to write a sinple program. Here's the flow:

1. Workqueue adds data to message queue
2. A Thread reads that data from the message queue
3. If the data it reads is a 1, it will adds another set of data to a ring buffer.

When i build my program it builds without any issues. But when i try to run it, it says "segmentation fault (core dumped)"
Below is the code I've written so far:

#include <zephyr.h>
#include <device.h>
#include <kernel.h>
#include <sys/ring_buffer.h>

#define STACK_SIZE 500
#define MY_PRIORITY1 1
#define MY_RING_BUF_SIZE 64


// Ring buffer info
struct my_struct {
    struct ring_buf rb;
    uint8_t buffer[MY_RING_BUF_SIZE];
};
struct my_struct ms;


// Message queue data item
struct data_item_type{
	uint32_t field1;
};

// Thread stack and data
K_THREAD_STACK_DEFINE(threadP_stack, STACK_SIZE);
struct k_thread threadP_data;

// Defining Workq
struct k_work_delayable work;

// Defining Messageq
char my_msgq_buffer[10 * sizeof(struct data_item_type)];
struct k_msgq my_msgq;

// Ring buffer stuff
void init_ringbuf()
{
    printk("Initializing ring buf");
    ring_buf_init(&ms.rb, sizeof(ms.buffer), ms.buffer);
}


// Workq Stuff
void callback()
{
    struct data_item_type data;
    data.field1 = 1;
    k_msgq_put(&my_msgq, &data.field1, K_NO_WAIT);
}

void init_workq()
{
    printk("Initializing Workq\n");
    k_work_init_delayable(&work, callback);
}

void start_workq(uint16_t delay)
{
    printk("Starting schedule");
    k_work_reschedule(&work, K_SECONDS(delay));
}




// Thread stuff
void threadP_func()
{
    struct data_item_type retrieve;
    uint8_t data[MY_RING_BUF_SIZE] = {1,2,3,4,5};
    while(1)
    {
        k_msgq_get(&my_msgq, &retrieve, K_FOREVER);
        if(retrieve.field1 == 1)
        {
            ring_buf_put(&ms.rb, data, SIZE32_OF(data));
            printk("Data added");
        }
    }
}

void main()
{
    k_thread_create(&threadP_data, threadP_stack, K_THREAD_STACK_SIZEOF(threadP_stack),
					threadP_func, NULL, NULL, NULL, MY_PRIORITY1, 0, K_NO_WAIT);
    k_thread_start(&threadP_data);

    init_workq();
    start_workq(5);
    init_ringbuf();
    k_thread_start(&threadP_data);
}

I'm also attaching a screenshot of the terminal:

What have i done wrong???