1 files changed, 43 insertions, 36 deletions

diff --git a/kernel/sys.c b/kernel/sys.c
index e423d0d9e6ff..895d2d4c9493 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -978,8 +978,7 @@ asmlinkage long sys_setpgid(pid_t pid, pid_t pgid)
                 goto out;
 
         if (task_pgrp(p) != pgrp) {
-                detach_pid(p, PIDTYPE_PGID);
-                attach_pid(p, PIDTYPE_PGID, pgrp);
+                change_pid(p, PIDTYPE_PGID, pgrp);
                 set_task_pgrp(p, pid_nr(pgrp));
         }
 
@@ -992,54 +991,67 @@ out:
 
 asmlinkage long sys_getpgid(pid_t pid)
 {
+        struct task_struct *p;
+        struct pid *grp;
+        int retval;
+
+        rcu_read_lock();
         if (!pid)
-                return task_pgrp_vnr(current);
+                grp = task_pgrp(current);
         else {
-                int retval;
-                struct task_struct *p;
-
-                read_lock(&tasklist_lock);
-                p = find_task_by_vpid(pid);
                 retval = -ESRCH;
-                if (p) {
-                        retval = security_task_getpgid(p);
-                        if (!retval)
-                                retval = task_pgrp_vnr(p);
-                }
-                read_unlock(&tasklist_lock);
-                return retval;
+                p = find_task_by_vpid(pid);
+                if (!p)
+                        goto out;
+                grp = task_pgrp(p);
+                if (!grp)
+                        goto out;
+
+                retval = security_task_getpgid(p);
+                if (retval)
+                        goto out;
         }
+        retval = pid_vnr(grp);
+out:
+        rcu_read_unlock();
+        return retval;
 }
 
 #ifdef __ARCH_WANT_SYS_GETPGRP
 
 asmlinkage long sys_getpgrp(void)
 {
-        /* SMP - assuming writes are word atomic this is fine */
-        return task_pgrp_vnr(current);
+        return sys_getpgid(0);
 }
 
 #endif
 
 asmlinkage long sys_getsid(pid_t pid)
 {
+        struct task_struct *p;
+        struct pid *sid;
+        int retval;
+
+        rcu_read_lock();
         if (!pid)
-                return task_session_vnr(current);
+                sid = task_session(current);
         else {
-                int retval;
-                struct task_struct *p;
-
-                rcu_read_lock();
-                p = find_task_by_vpid(pid);
                 retval = -ESRCH;
-                if (p) {
-                        retval = security_task_getsid(p);
-                        if (!retval)
-                                retval = task_session_vnr(p);
-                }
-                rcu_read_unlock();
-                return retval;
+                p = find_task_by_vpid(pid);
+                if (!p)
+                        goto out;
+                sid = task_session(p);
+                if (!sid)
+                        goto out;
+
+                retval = security_task_getsid(p);
+                if (retval)
+                        goto out;
         }
+        retval = pid_vnr(sid);
+out:
+        rcu_read_unlock();
+        return retval;
 }
 
 asmlinkage long sys_setsid(void)
@@ -1572,11 +1584,8 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
                 goto out;
         }
 
-        rcu_read_lock();
-        if (!lock_task_sighand(p, &flags)) {
-                rcu_read_unlock();
+        if (!lock_task_sighand(p, &flags))
                 return;
-        }
 
         switch (who) {
                 case RUSAGE_BOTH:
@@ -1612,9 +1621,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
                 default:
                         BUG();
         }
-
         unlock_task_sighand(p, &flags);
-        rcu_read_unlock();
 
 out:
         cputime_to_timeval(utime, &r->ru_utime);