Thread: Lost with wrong output

I can't see how this code isn't getting the output which should be:

buffer elem = -378931907
buffer elem = 1991142473
buffer elem = -2051466334
buffer elem = -1945167320
buffer elem = 1080018178

Rather than:

buffer elem = 1343403155
buffer elem = 225005971
buffer elem = 1270463783
buffer elem = -1162132598
buffer elem = 636863738

The thread is suppose to be suspended given: if((b->in+1)%b->max_buffer_size == b->out) then await it's signal from get_buffer to add more to the buffer. The maximum buffer size has been initialised to 5.

What is the source of this problem?

from put buffer = -378931907
from put buffer = 1991142473
from put buffer = -2051466334
from put buffer = -1945167320
from put buffer = 1080018178
from put buffer = 1343403155
from put buffer = 225005971
from put buffer = 1270463783
from put buffer = -1162132598
from put buffer = 636863738

Code:

void init_buffer(bufferQueue *b, semaphore s, int min, int max)
{

        b->buffer_array = malloc(max*sizeof(int));
        b->in = 0;
        b->out = 0;
        b->min_buffer_size = min;
        b->max_buffer_size = max;
        b->sem = s;

}

Code:

void put_buffer(bufferQueue *b, int v)
{

        if((b->in+1)%b->max_buffer_size == b->out)
        {

                semWait(&(b->sem));

        }

        b->buffer_array[b->in] = v;
        printf("from put buffer = %d\n", b->buffer_array[b->in]);
        b->in = (b->in+1)%b->max_buffer_size;
        semSignal(&(b->sem));

}

Code:

void *producer(void* cb)
{
        printf("testing\n");
        bufferQueue *cbuffer = (bufferQueue *)cb;
        int  i;
        for(i = 0; i < 10; i++)
        {
                put_buffer(cbuffer, randomNum());
        }

        for(i = 0; i < 5; i++)
        {
                printf("buffer elem = %d\n", cbuffer->buffer_array[i]);
        }

        destroy_buffer(cbuffer);
        return cb;
}

int main(void)
{
        semaphore sem;
        bufferQueue cbuffer;
        pthread_t thread;

        init_sem(&sem);
        init_buffer(&cbuffer, sem, 0, 5);

        pthread_create(&thread, NULL, producer, (void*)(&cbuffer));