[PATCH] pid allocator bugfix

This patch fixes a bug in the Linux process ID allocator.  It isn't quite
SMP safe since it references "last_pid" after releasing the lock protecting
it.  This can result in two processes getting assigned the same process ID.

kernel/fork.c

@@ -129,6 +129,7 @@ static int get_pid(unsigned long flags)
 {
 	static int next_safe = PID_MAX;
 	struct task_struct *p;
+	int pid;
 
 	if (flags & CLONE_PID)
 		return current->pid;
@@ -164,9 +165,10 @@ static int get_pid(unsigned long flags)
 		}
 		read_unlock(&tasklist_lock);
 	}
+	pid = last_pid;
 	spin_unlock(&lastpid_lock);
 
-	return last_pid;
+	return pid;
 }
 
 static inline int dup_mmap(struct mm_struct * mm)