Where could there be a deadlock happening?

Question

thanks for reading! I am using C PThreads library to experiment with threading. Basically what I am doing is reading in a text file that the first line has two numbers: amount of threads, and amount of rounds. What this will do is create threads and loop them a rounds amount of time to generate random numbers.

What happens is that I get the correct numbers based off a function for the first round but then the function never gets called after that.

This is the code

int main(){
    FILE *fp = fopen(argv[1], "r");
    //Print the name of the file
    printf("%s\n", argv[1]);
    if(fp == NULL){
        printf("Error opening file\n");
        return 1;
    }
    int num_threads, num_rounds;
    fscanf(fp, "%d %d", &num_threads, &num_rounds);
    struct thread_args *args = malloc(sizeof(struct thread_args) * num_threads);
    for(int i = 0; i < num_threads; i++){
        fscanf(fp, "%d %d %d %d", &args[i].a, &args[i].c, &args[i].m, &args[i].x);
        args[i].points = 0;
    }
    //close the file
    fclose(fp);
    //Create the threads. Each thread will be assigned a number from 0 to num_threads-1.
    pthread_t tid[num_threads];
    pthread_attr_t attr;
    pthread_attr_init(&attr);
    //Create the threads
    for(int i = 0; i < num_threads; i++){
        pthread_create(&tid[i], &attr, runner, &args[i]);
    }
    //For each round
    for (int i = 1; i<num_rounds;i++ ){
        for (int j = 0;j<num_threads;j++){
            pthread_cond_signal(&cVar);
            run = 1;
            sleep(1);
        }
        printf("\n");
    }
    //Join the threads
    for(int i = 0; i < num_threads; i++){
        pthread_join(tid[i], NULL);
    }
    //Free the memory
    free(args);
    return 0;
}

This is main ^

This is the runner function:

void *runner(void *param){
    
    struct thread_args *args = (struct thread_args *)param;
    int x = args->x;
    int a = args->a;
    int c = args->c;
    int m = args->m;
    int points = args->points;
    int x_new;
    while(run == -1){
        pthread_mutex_lock(&mVar);
        pthread_cond_wait(&cVar, &mVar);
        x_new = f1(x, a, c, m);
        printf("%d\n", x_new);
        args->x = x_new;
        pthread_mutex_unlock(&mVar);
    }

    pthread_exit(NULL);

}

and this is the function used to create a "random" number:

    long int x1 = x*a+c;
    return (int)(x1%m);
}```

Any explanation for this would be great! Thanks!