Removing has_group_leader_pid

With de_thread now calling exchange_tids has_group_leader_pid no longer
makes any sense and is equivalent to calling thread_group_leader.

As there are only 2 remaining users of has_group_leader_pid let's
update the code and get rid of has_group_leader_pid.

There is one extra patch to lookup_task that performs that unifies
to code paths that become identical when has_group_leader_pid went
away.

Eric W. Biederman (4):
      posix-cpu-timer: Tidy up group_leader logic in lookup_task
      posix-cpu-timer:  Unify the now redundant code in lookup_task
      exec: Remove BUG_ON(has_group_leader_pid)
      signal: Remove has_group_leader_pid

 fs/exec.c                      |  1 -
 include/linux/sched/signal.h   | 11 -----------
 kernel/time/posix-cpu-timers.c | 21 ++++++++-------------
 3 files changed, 8 insertions(+), 25 deletions(-)

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

1 files changed, 8 insertions, 13 deletions

diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index 2fd3b3fa68bf..b7f972fb115e 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -66,23 +66,18 @@ static struct task_struct *lookup_task(const pid_t pid, bool thread,
 	if (thread)
 		return same_thread_group(p, current) ? p : NULL;
 
-	if (gettime) {
-		/*
-		 * For clock_gettime(PROCESS) the task does not need to be
-		 * the actual group leader. tsk->sighand 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 clock_gettime(PROCESS) the task does not need to be
+	 * the actual group leader. task->signal gives
+	 * access to the group's clock.
+	 */
+	if (gettime && (p == current))
+		return p;
 
 	/*
 	 * 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,