kernel: efficient way to find task_struct by pid?

Question

Is there an efficient way of finding the task_struct for a specified pid, without iterating through the task_struct list?

Answer 1

What's wrong with using one of the following?

extern struct task_struct *find_task_by_vpid(pid_t nr);
extern struct task_struct *find_task_by_pid_ns(pid_t nr,
            struct pid_namespace *ns);

Answer 2

If you want to find the task_struct from a module, find_task_by_vpid(pid_t nr) etc. are not going to work since these functions are not exported.

In a module, you can use the following function instead:

pid_task(find_vpid(pid), PIDTYPE_PID);