Question

I have written a module where a user can read or write to a proc file – how do I determine the number of threads in a user process that is reading or writing in kernel-level programming?

Answer 1

Use current as a pointer to the current task (current task_struct) inside your read/write function:

#include <linux/sched.h>

struct task_struct * t;
for (t = next_thread(current); t != current; t = next_thread(t)) {
    // do the stuff
}