kernel/fork.c: check error and return early

Thus reducing one indentation level while maintaining the same rationale.

Link: http://lkml.kernel.org/r/20171117002929.5155-1-marcos.souza.org@gmail.comSigned-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/fork.c

@@ -2062,6 +2062,8 @@ long _do_fork(unsigned long clone_flags,
 	      int __user *child_tidptr,
 	      unsigned long tls)
 {
+	struct completion vfork;
+	struct pid *pid;
 	struct task_struct *p;
 	int trace = 0;
 	long nr;
@@ -2087,14 +2089,14 @@ long _do_fork(unsigned long clone_flags,
 	p = copy_process(clone_flags, stack_start, stack_size,
 			 child_tidptr, NULL, trace, tls, NUMA_NO_NODE);
 	add_latent_entropy();
+
+	if (IS_ERR(p))
+		return PTR_ERR(p);
+
 	/*
 	 * Do this prior waking up the new thread - the thread pointer
 	 * might get invalid after that point, if the thread exits quickly.
 	 */
-	if (!IS_ERR(p)) {
-		struct completion vfork;
-		struct pid *pid;
-
 	trace_sched_process_fork(current, p);
 
 	pid = get_task_pid(p, PIDTYPE_PID);
@@ -2121,9 +2123,6 @@ long _do_fork(unsigned long clone_flags,
 	}
 
 	put_pid(pid);
-	} else {
-		nr = PTR_ERR(p);
-	}
 	return nr;
 }