pidns: remove find_task_by_pid, unused for a long time

It seems to me that it was a mistake marking this function as deprecated
and scheduling it for removal, rather than resolutely removing it after
the last caller's death.

Anyway - better late, then never.

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/feature-removal-schedule.txt

@@ -138,24 +138,6 @@ Who:	Kay Sievers <kay.sievers@suse.de>
 
 ---------------------------
 
-What:	find_task_by_pid
-When:	2.6.26
-Why:	With pid namespaces, calling this funciton will return the
-	wrong task when called from inside a namespace.
-
-	The best way to save a task pid and find a task by this
-	pid later, is to find this task's struct pid pointer (or get
-	it directly from the task) and call pid_task() later.
-
-	If someone really needs to get a task by its pid_t, then
-	he most likely needs the find_task_by_vpid() to get the
-	task from the same namespace as the current task is in, but
-	this may be not so in general.
-
-Who:	Pavel Emelyanov <xemul@openvz.org>
-
----------------------------
-
 What:	ACPI procfs interface
 When:	July 2008
 Why:	ACPI sysfs conversion should be finished by January 2008.

include/linux/pid.h

@@ -107,7 +107,7 @@ extern struct pid_namespace init_pid_ns;
  * find_pid_ns() finds the pid in the namespace specified
  * find_vpid() finr the pid by its virtual id, i.e. in the current namespace
  *
- * see also find_task_by_pid() set in include/linux/sched.h
+ * see also find_task_by_vpid() set in include/linux/sched.h
  */
 extern struct pid *find_pid_ns(int nr, struct pid_namespace *ns);
 extern struct pid *find_vpid(int nr);

include/linux/sched.h

@@ -1715,19 +1715,13 @@ extern struct pid_namespace init_pid_ns;
  *      finds a task by its pid in the specified namespace
  * find_task_by_vpid():
  *      finds a task by its virtual pid
- * find_task_by_pid():
- *      finds a task by its global pid
  *
  * see also find_vpid() etc in include/linux/pid.h
  */
 
 extern struct task_struct *find_task_by_pid_type_ns(int type, int pid,
 		struct pid_namespace *ns);
 
-static inline struct task_struct *__deprecated find_task_by_pid(pid_t nr)
-{
-	return find_task_by_pid_type_ns(PIDTYPE_PID, nr, &init_pid_ns);
-}
 extern struct task_struct *find_task_by_vpid(pid_t nr);
 extern struct task_struct *find_task_by_pid_ns(pid_t nr,
 		struct pid_namespace *ns);