[PATCH] add process_session() helper routine

Replace occurences of task->signal->session by a new process_session() helper
routine.

It will be useful for pid namespaces to abstract the session pid number.

Signed-off-by: Cedric Le Goater <clg@fr.ibm.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Sukadev Bhattiprolu <sukadev@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

4 files changed, 17 insertions, 16 deletions

diff --git a/kernel/exit.c b/kernel/exit.c
index fa0495e167e..8d289bfc13d 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -193,14 +193,14 @@ int session_of_pgrp(int pgrp)
 
         read_lock(&tasklist_lock);
         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
-                if (p->signal->session > 0) {
-                        sid = p->signal->session;
+                if (process_session(p) > 0) {
+                        sid = process_session(p);
                         goto out;
                 }
         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
         p = find_task_by_pid(pgrp);
         if (p)
-                sid = p->signal->session;
+                sid = process_session(p);
 out:
         read_unlock(&tasklist_lock);
         
@@ -225,8 +225,8 @@ static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task)
                                 || p->exit_state
                                 || is_init(p->real_parent))
                         continue;
-                if (process_group(p->real_parent) != pgrp
-                            && p->real_parent->signal->session == p->signal->session) {
+                if (process_group(p->real_parent) != pgrp &&
+                    process_session(p->real_parent) == process_session(p)) {
                         ret = 0;
                         break;
                 }
@@ -302,7 +302,7 @@ void __set_special_pids(pid_t session, pid_t pgrp)
 {
         struct task_struct *curr = current->group_leader;
 
-        if (curr->signal->session != session) {
+        if (process_session(curr) != session) {
                 detach_pid(curr, PIDTYPE_SID);
                 curr->signal->session = session;
                 attach_pid(curr, PIDTYPE_SID, session);
@@ -647,10 +647,11 @@ reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
          * outside, so the child pgrp is now orphaned.
          */
         if ((process_group(p) != process_group(father)) &&
-            (p->signal->session == father->signal->session)) {
+            (process_session(p) == process_session(father))) {
                 int pgrp = process_group(p);
 
-                if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
+                if (will_become_orphaned_pgrp(pgrp, NULL) &&
+                    has_stopped_jobs(pgrp)) {
                         __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
                         __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
                 }
@@ -784,7 +785,7 @@ static void exit_notify(struct task_struct *tsk)
         t = tsk->real_parent;
         
         if ((process_group(t) != process_group(tsk)) &&
-            (t->signal->session == tsk->signal->session) &&
+            (process_session(t) == process_session(tsk)) &&
             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
             has_stopped_jobs(process_group(tsk))) {
                 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
diff --git a/kernel/fork.c b/kernel/fork.c
index 59770781932..298c4d6ab51 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1259,9 +1259,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
                 if (thread_group_leader(p)) {
                         p->signal->tty = current->signal->tty;
                         p->signal->pgrp = process_group(current);
-                        p->signal->session = current->signal->session;
+                        p->signal->session = process_session(current);
                         attach_pid(p, PIDTYPE_PGID, process_group(p));
-                        attach_pid(p, PIDTYPE_SID, p->signal->session);
+                        attach_pid(p, PIDTYPE_SID, process_session(p));
 
                         list_add_tail_rcu(&p->tasks, &init_task.tasks);
                         __get_cpu_var(process_counts)++;
diff --git a/kernel/signal.c b/kernel/signal.c
index ec81defde33..9eac4db60ed 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -583,7 +583,7 @@ static int check_kill_permission(int sig, struct siginfo *info,
         error = -EPERM;
         if ((info == SEND_SIG_NOINFO || (!is_si_special(info) && SI_FROMUSER(info)))
             && ((sig != SIGCONT) ||
-                (current->signal->session != t->signal->session))
+                (process_session(current) != process_session(t)))
             && (current->euid ^ t->suid) && (current->euid ^ t->uid)
             && (current->uid ^ t->suid) && (current->uid ^ t->uid)
             && !capable(CAP_KILL))
diff --git a/kernel/sys.c b/kernel/sys.c
index 1ac2d1c5d84..4f9d23a3095 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1381,7 +1381,7 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
 
         if (p->real_parent == group_leader) {
                 err = -EPERM;
-                if (p->signal->session != group_leader->signal->session)
+                if (process_session(p) != process_session(group_leader))
                         goto out;
                 err = -EACCES;
                 if (p->did_exec)
@@ -1400,7 +1400,7 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
                 struct task_struct *p;
 
                 do_each_task_pid(pgid, PIDTYPE_PGID, p) {
-                        if (p->signal->session == group_leader->signal->session)
+                        if (process_session(p) == process_session(group_leader))
                                 goto ok_pgid;
                 } while_each_task_pid(pgid, PIDTYPE_PGID, p);
                 goto out;
@@ -1459,7 +1459,7 @@ asmlinkage long sys_getpgrp(void)
 asmlinkage long sys_getsid(pid_t pid)
 {
         if (!pid)
-                return current->signal->session;
+                return process_session(current);
         else {
                 int retval;
                 struct task_struct *p;
@@ -1471,7 +1471,7 @@ asmlinkage long sys_getsid(pid_t pid)
                 if (p) {
                         retval = security_task_getsid(p);
                         if (!retval)
-                                retval = p->signal->session;
+                                retval = process_session(p);
                 }
                 read_unlock(&tasklist_lock);
                 return retval;