pids: kill signal_struct-> __pgrp/__session and friends

We are wasting 2 words in signal_struct without any reason to implement
task_pgrp_nr() and task_session_nr().

task_session_nr() has no callers since
2e2ba22ea4fd4bb85f0fa37c521066db6775cbef, we can remove it.

task_pgrp_nr() is still (I believe wrongly) used in fs/autofsX and
fs/coda.

This patch reimplements task_pgrp_nr() via task_pgrp_nr_ns(), and kills
__pgrp/__session and the related helpers.

The change in drivers/char/tty_io.c is cosmetic, but hopefully makes sense
anyway.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Alan Cox <number6@the-village.bc.nu>		[tty parts]
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 12 insertions, 51 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index a44b701c5bba..66b99a2049e3 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -2681,7 +2681,7 @@ void __do_SAK(struct tty_struct *tty)
         /* Kill the entire session */
         do_each_pid_task(session, PIDTYPE_SID, p) {
                 printk(KERN_NOTICE "SAK: killed process %d"
-                        " (%s): task_session_nr(p)==tty->session\n",
+                        " (%s): task_session(p)==tty->session\n",
                         task_pid_nr(p), p->comm);
                 send_sig(SIGKILL, p, 1);
         } while_each_pid_task(session, PIDTYPE_SID, p);
@@ -2691,7 +2691,7 @@ void __do_SAK(struct tty_struct *tty)
         do_each_thread(g, p) {
                 if (p->signal->tty == tty) {
                         printk(KERN_NOTICE "SAK: killed process %d"
-                            " (%s): task_session_nr(p)==tty->session\n",
+                            " (%s): task_session(p)==tty->session\n",
                             task_pid_nr(p), p->comm);
                         send_sig(SIGKILL, p, 1);
                         continue;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 49df878a0cad..206ac003e8c0 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -547,25 +547,8 @@ struct signal_struct {
 
         struct list_head cpu_timers[3];
 
-        /* job control IDs */
-
-        /*
-         * pgrp and session fields are deprecated.
-         * use the task_session_Xnr and task_pgrp_Xnr routines below
-         */
-
-        union {
-                pid_t pgrp __deprecated;
-                pid_t __pgrp;
-        };
-
         struct pid *tty_old_pgrp;
 
-        union {
-                pid_t session __deprecated;
-                pid_t __session;
-        };
-
         /* boolean value for session group leader */
         int leader;
 
@@ -1469,16 +1452,6 @@ static inline int rt_task(struct task_struct *p)
         return rt_prio(p->prio);
 }
 
-static inline void set_task_session(struct task_struct *tsk, pid_t session)
-{
-        tsk->signal->__session = session;
-}
-
-static inline void set_task_pgrp(struct task_struct *tsk, pid_t pgrp)
-{
-        tsk->signal->__pgrp = pgrp;
-}
-
 static inline struct pid *task_pid(struct task_struct *task)
 {
         return task->pids[PIDTYPE_PID].pid;
@@ -1552,11 +1525,6 @@ static inline pid_t task_tgid_vnr(struct task_struct *tsk)
 }
 
 
-static inline pid_t task_pgrp_nr(struct task_struct *tsk)
-{
-        return tsk->signal->__pgrp;
-}
-
 static inline pid_t task_pgrp_nr_ns(struct task_struct *tsk,
                                         struct pid_namespace *ns)
 {
@@ -1569,11 +1537,6 @@ static inline pid_t task_pgrp_vnr(struct task_struct *tsk)
 }
 
 
-static inline pid_t task_session_nr(struct task_struct *tsk)
-{
-        return tsk->signal->__session;
-}
-
 static inline pid_t task_session_nr_ns(struct task_struct *tsk,
                                         struct pid_namespace *ns)
 {
@@ -1585,6 +1548,12 @@ static inline pid_t task_session_vnr(struct task_struct *tsk)
         return __task_pid_nr_ns(tsk, PIDTYPE_SID, NULL);
 }
 
+/* obsolete, do not use */
+static inline pid_t task_pgrp_nr(struct task_struct *tsk)
+{
+        return task_pgrp_nr_ns(tsk, &init_pid_ns);
+}
+
 /**
  * pid_alive - check that a task structure is not stale
  * @p: Task structure to be checked.
diff --git a/kernel/exit.c b/kernel/exit.c
index 384f09caf2ef..3bec141c82f6 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -357,16 +357,12 @@ static void reparent_to_kthreadd(void)
 void __set_special_pids(struct pid *pid)
 {
         struct task_struct *curr = current->group_leader;
-        pid_t nr = pid_nr(pid);
 
-        if (task_session(curr) != pid) {
+        if (task_session(curr) != pid)
                 change_pid(curr, PIDTYPE_SID, pid);
-                set_task_session(curr, nr);
-        }
-        if (task_pgrp(curr) != pid) {
+
+        if (task_pgrp(curr) != pid)
                 change_pid(curr, PIDTYPE_PGID, pid);
-                set_task_pgrp(curr, nr);
-        }
 }
 
 static void set_special_pids(struct pid *pid)
diff --git a/kernel/fork.c b/kernel/fork.c
index adbea16ec649..f74458231449 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1265,8 +1265,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                         p->signal->leader_pid = pid;
                         tty_kref_put(p->signal->tty);
                         p->signal->tty = tty_kref_get(current->signal->tty);
-                        set_task_pgrp(p, task_pgrp_nr(current));
-                        set_task_session(p, task_session_nr(current));
                         attach_pid(p, PIDTYPE_PGID, task_pgrp(current));
                         attach_pid(p, PIDTYPE_SID, task_session(current));
                         list_add_tail_rcu(&p->tasks, &init_task.tasks);
diff --git a/kernel/sys.c b/kernel/sys.c
index 37f458e6882a..742cefa527e6 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1013,10 +1013,8 @@ SYSCALL_DEFINE2(setpgid, pid_t, pid, pid_t, pgid)
         if (err)
                 goto out;
 
-        if (task_pgrp(p) != pgrp) {
+        if (task_pgrp(p) != pgrp)
                 change_pid(p, PIDTYPE_PGID, pgrp);
-                set_task_pgrp(p, pid_nr(pgrp));
-        }
 
         err = 0;
 out: