thread or mutex SIGTRAP in multiple threads program

[heatblazer]

Hello,
I am trying a multithreaded code but I am recieving sigtrap. I am trying to test a round robin algorithm but somehow I am SIGTRAPing in the atomic_push function.

typedef struct _s
{
    char system[32];
    struct _s* next;
} node;


static node* s_head = 0;
static pthread_mutex_t mutex;


static void atomic_push(node** pHeader, const char* data)
{


    pthread_mutex_init(&mutex, NULL);
    pthread_mutex_lock(&mutex);
    critical_section:
    {
        node* pnode = (node*) malloc(sizeof(node));
        strcpy(pnode->system, data);
        pnode->next = (*pHeader);
        (*pHeader) = pnode;
    }
    pthread_mutex_unlock(&mutex);
}


static const char* systems[4] =
{
    {"system1"},
    {"system2"},
    {"system3"},
    {"system4"}
};




static int fetch_and_add(int* pVar, int value)
{
    asm volatile ("lock; xaddl %%eax, %2;"
                  :"=a"(value)
                  :"a" (value), "m" (*pVar)
                  :"memory");
    return value;
}


static int atomic_int = 1;


static void run(void)
{
    char* str = systems[fetch_and_add(&atomic_int, 1) % 4];
    atomic_push(&s_head, str);
}




int main(void)
{


    int i = 0;
    pthread_t tids[500];


    for(i=0; i < 500; i++) {
        pthread_create(&tids[i],0, &run, 0);
        usleep(200);
    }


    node* it = &s_head;
    i =0;
    while ( it != NULL ) {


        printf("[%d]:[%s]\n", i++, it->system);
        it = it->next;
    }




    return 0;
}

A help will be appreciated.

[Codeplug]

You only call pthread_mutex_init once, and then use that initialized mutex for the remainder of its lifetime.

Also add error checking.

You need to call pthread_join on all your created threads before exiting main.

gg

[heatblazer]

You only call pthread_mutex_init once, and then use that initialized mutex for the remainder of its lifetime.

Also add error checking.

You need to call pthread_join on all your created threads before exiting main.

gg

Hello,
actually I had a wrong iterator for printing the list, but thanks for the reminder of the joining the threads.

//node* it = (&s_head);
node* it = *(&s_head);

I was iterating to the list of lists, not trough the nodes. . .