C pthread_join segmentation fault - c

Question

I am trying to write a C program that calculates the size of a directory tree using threads for my assignment.
My code works fine when there is only one subdirectory, however whenever I have 2 or more subdirectories, I am getting a Segmentation Fault error. I was reading a lot about it and was not able to find a reason for my code to fail.
In my global scope:
pthread_mutex_t mutex;
int total_size = 0; // Global, to accumulate the size
main():
int main(int argc, char *argv[])
{
pthread_t thread;
...
if (pthread_mutex_init(&mutex, NULL) < 0)
{
perror("pthread_mutex_init");
exit(1);
}
pthread_create(&thread, NULL, dirsize, (void*)dirpath);
pthread_join(thread, NULL);
printf("\nTotal size: %d\n\n", total_size);
...
}
My dirsize() function:
void* dirsize(void* dir)
{
...
pthread_t tid[100];
int threads_created = 0;
dp=opendir(dir);
chdir(dir);
// Loop over files in directory
while ((entry = readdir(dp)) != NULL)
{
...
// Check if directory
if (S_ISDIR(statbuf.st_mode))
{
// Create new thread & call itself recursively
pthread_create(&tid[threads_created], NULL, dirsize, (void*)entry->d_name);
threads_created++;
}
else
{
// Add filesize
pthread_mutex_lock(&mutex);
total_size += statbuf.st_size;
pthread_mutex_unlock(&mutex);
}
}
for (i = 0; i < threads_created; i++)
{
pthread_join(tid[i], NULL);
}
}
What am I doing wrong here? Would greatly appreciate if you could point me to the right direction.
Here is what I'm getting through gdb: http://pastebin.com/TUkHspHH
Thank you in advance!

Answer 1

What's the value of NUM_THREADS?
// Check if directory
if (S_ISDIR(statbuf.st_mode))
{
// Create new thread & call itself recursively
pthread_create(&tid[threads_created], NULL, dirsize, (void*)entry->d_name);
threads_created++;
}
Here you should check if threads_created is equal to NUM_THREADS and if so increase the size of the tid array (that I would malloc at the function begin and free at the end, btw).
Moreover you should allocate a copy of the directory name (malloc + strcpy) before you pass it as argument to the thread and free such copy at the end of the function instead of entry->d_name.