Replace has_group_leader_pid with thread_group_leader. Years ago Oleg
suggested changing thread_group_leader to has_group_leader_pid to handle
races. Looking at the code then and now I don't see how it ever helped.
Especially as then the code really did need to be the
thread_group_leader.
Today it doesn't make a difference if thread_group_leader races with
de_thread as the task returned from lookup_task in the non-thread case is
just used to find values in task->signal.
Since the races with de_thread have never been handled revert
has_group_header_pid to thread_group_leader for clarity.
Update the comment in lookup_task to remove implementation details that
are no longer true and to mention task->signal instead of task->sighand,
as the relevant cpu timer details are all in task->signal.
Ref:
55e8c8eb2c7b ("posix-cpu-timers: Store a reference to a pid not a task")
Ref:
c0deae8c9587 ("posix-cpu-timers: Rcu_read_lock/unlock protect find_task_by_vpid call")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
if (gettime) {
/*
* For clock_gettime(PROCESS) the task does not need to be
- * the actual group leader. tsk->sighand gives
+ * the actual group leader. task->signal gives
* access to the group's clock.
- *
- * Timers need the group leader because they take a
- * reference on it and store the task pointer until the
- * timer is destroyed.
*/
return (p == current || thread_group_leader(p)) ? p : NULL;
}
/*
* For processes require that p is group leader.
*/
- return has_group_leader_pid(p) ? p : NULL;
+ return thread_group_leader(p) ? p : NULL;
}
static struct task_struct *__get_task_for_clock(const clockid_t clock,