sys_setpgid(): simplify pid/ns interaction

sys_setpgid() does unneeded conversions from pid_t to "struct pid" and vice
versa.  Use "struct pid" more consistently.  Saves one find_vpid() and
eliminates the explicit usage of ->nsproxy->pid_ns.  Imho, cleanups the
code.

Also use the same_thread_group() helper.

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

1 files changed, 10 insertions, 13 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index e3c08d4324d..42136dd453d 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -916,8 +916,8 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
 {
         struct task_struct *p;
         struct task_struct *group_leader = current->group_leader;
-        int err = -EINVAL;
-        struct pid_namespace *ns;
+        struct pid *pgrp;
+        int err;
 
         if (!pid)
                 pid = task_pid_vnr(group_leader);
@@ -929,12 +929,10 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
         /* From this point forward we keep holding onto the tasklist lock
          * so that our parent does not change from under us. -DaveM
          */
-        ns = current->nsproxy->pid_ns;
-
         write_lock_irq(&tasklist_lock);
 
         err = -ESRCH;
-        p = find_task_by_pid_ns(pid, ns);
+        p = find_task_by_vpid(pid);
         if (!p)
                 goto out;
 
@@ -942,7 +940,7 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
         if (!thread_group_leader(p))
                 goto out;
 
-        if (p->real_parent->tgid == group_leader->tgid) {
+        if (same_thread_group(p->real_parent, group_leader)) {
                 err = -EPERM;
                 if (task_session(p) != task_session(group_leader))
                         goto out;
@@ -959,10 +957,12 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
         if (p->signal->leader)
                 goto out;
 
+        pgrp = task_pid(p);
         if (pgid != pid) {
                 struct task_struct *g;
 
-                g = find_task_by_pid_type_ns(PIDTYPE_PGID, pgid, ns);
+                pgrp = find_vpid(pgid);
+                g = pid_task(pgrp, PIDTYPE_PGID);
                 if (!g || task_session(g) != task_session(group_leader))
                         goto out;
         }
@@ -971,13 +971,10 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
         if (err)
                 goto out;
 
-        if (task_pgrp_nr_ns(p, ns) != pgid) {
-                struct pid *pid;
-
+        if (task_pgrp(p) != pgrp) {
                 detach_pid(p, PIDTYPE_PGID);
-                pid = find_vpid(pgid);
-                attach_pid(p, PIDTYPE_PGID, pid);
-                set_task_pgrp(p, pid_nr(pid));
+                attach_pid(p, PIDTYPE_PGID, pgrp);
+                set_task_pgrp(p, pid_nr(pgrp));
         }
 
         err = 0;