[PATCH] pid: implement pid_nr

As we stop storing pid_t's and move to storing struct pid *.  We need a way to
get the pid_t from the struct pid to report to user space what we have stored.

Having a clean well defined way to do this is especially important as we move
to multiple pid spaces as may need to report a different value to the caller
depending on which pid space the caller is in.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/pid.h

@@ -94,6 +94,14 @@ extern struct pid *find_ge_pid(int nr);
 extern struct pid *alloc_pid(void);
 extern void FASTCALL(free_pid(struct pid *pid));
 
+static inline pid_t pid_nr(struct pid *pid)
+{
+	pid_t nr = 0;
+	if (pid)
+		nr = pid->nr;
+	return nr;
+}
+
 #define pid_next(task, type)					\
 	((task)->pids[(type)].node.next)