signal: Use SEND_SIG_PRIV not SEND_SIG_FORCED with SIGKILL and SIGSTOP

Now that siginfo is never allocated for SIGKILL and SIGSTOP there is
no difference between SEND_SIG_PRIV and SEND_SIG_FORCED for SIGKILL
and SIGSTOP.  This makes SEND_SIG_FORCED unnecessary and redundant in
the presence of SIGKILL and SIGSTOP.  Therefore change users of
SEND_SIG_FORCED that are sending SIGKILL or SIGSTOP to use
SEND_SIG_PRIV instead.

This removes the last users of SEND_SIG_FORCED.

Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>

kernel/pid_namespace.c

@@ -216,7 +216,7 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns)
 	idr_for_each_entry_continue(&pid_ns->idr, pid, nr) {
 		task = pid_task(pid, PIDTYPE_PID);
 		if (task && !__fatal_signal_pending(task))
-			send_sig_info(SIGKILL, SEND_SIG_FORCED, task);
+			send_sig_info(SIGKILL, SEND_SIG_PRIV, task);
 	}
 	read_unlock(&tasklist_lock);
 	rcu_read_unlock();

kernel/ptrace.c

@@ -396,7 +396,7 @@ static int ptrace_attach(struct task_struct *task, long request,
 
 	/* SEIZE doesn't trap tracee on attach */
 	if (!seize)
-		send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
+		send_sig_info(SIGSTOP, SEND_SIG_PRIV, task);
 
 	spin_lock(&task->sighand->siglock);
 
@@ -563,7 +563,7 @@ void exit_ptrace(struct task_struct *tracer, struct list_head *dead)
 
 	list_for_each_entry_safe(p, n, &tracer->ptraced, ptrace_entry) {
 		if (unlikely(p->ptrace & PT_EXITKILL))
-			send_sig_info(SIGKILL, SEND_SIG_FORCED, p);
+			send_sig_info(SIGKILL, SEND_SIG_PRIV, p);
 
 		if (__ptrace_detach(tracer, p))
 			list_add(&p->ptrace_entry, dead);

mm/oom_kill.c

@@ -858,7 +858,7 @@ static void __oom_kill_process(struct task_struct *victim)
 	 * in order to prevent the OOM victim from depleting the memory
 	 * reserves from the user space under its control.
 	 */
-	do_send_sig_info(SIGKILL, SEND_SIG_FORCED, victim, PIDTYPE_TGID);
+	do_send_sig_info(SIGKILL, SEND_SIG_PRIV, victim, PIDTYPE_TGID);
 	mark_oom_victim(victim);
 	pr_err("Killed process %d (%s) total-vm:%lukB, anon-rss:%lukB, file-rss:%lukB, shmem-rss:%lukB\n",
 		task_pid_nr(victim), victim->comm, K(victim->mm->total_vm),
@@ -896,7 +896,7 @@ static void __oom_kill_process(struct task_struct *victim)
 		 */
 		if (unlikely(p->flags & PF_KTHREAD))
 			continue;
-		do_send_sig_info(SIGKILL, SEND_SIG_FORCED, p, PIDTYPE_TGID);
+		do_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_TGID);
 	}
 	rcu_read_unlock();