1 files changed, 10 insertions, 23 deletions

diff --git a/kernel/itimer.c b/kernel/itimer.c
index ab982747d9bd..db7c358b9a02 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -55,17 +55,15 @@ int do_getitimer(int which, struct itimerval *value)
                 spin_unlock_irq(&tsk->sighand->siglock);
                 break;
         case ITIMER_VIRTUAL:
-                read_lock(&tasklist_lock);
                 spin_lock_irq(&tsk->sighand->siglock);
                 cval = tsk->signal->it_virt_expires;
                 cinterval = tsk->signal->it_virt_incr;
                 if (!cputime_eq(cval, cputime_zero)) {
-                        struct task_struct *t = tsk;
-                        cputime_t utime = tsk->signal->utime;
-                        do {
-                                utime = cputime_add(utime, t->utime);
-                                t = next_thread(t);
-                        } while (t != tsk);
+                        struct task_cputime cputime;
+                        cputime_t utime;
+
+                        thread_group_cputime(tsk, &cputime);
+                        utime = cputime.utime;
                         if (cputime_le(cval, utime)) { /* about to fire */
                                 cval = jiffies_to_cputime(1);
                         } else {
@@ -73,25 +71,19 @@ int do_getitimer(int which, struct itimerval *value)
                         }
                 }
                 spin_unlock_irq(&tsk->sighand->siglock);
-                read_unlock(&tasklist_lock);
                 cputime_to_timeval(cval, &value->it_value);
                 cputime_to_timeval(cinterval, &value->it_interval);
                 break;
         case ITIMER_PROF:
-                read_lock(&tasklist_lock);
                 spin_lock_irq(&tsk->sighand->siglock);
                 cval = tsk->signal->it_prof_expires;
                 cinterval = tsk->signal->it_prof_incr;
                 if (!cputime_eq(cval, cputime_zero)) {
-                        struct task_struct *t = tsk;
-                        cputime_t ptime = cputime_add(tsk->signal->utime,
-                                                      tsk->signal->stime);
-                        do {
-                                ptime = cputime_add(ptime,
-                                                    cputime_add(t->utime,
-                                                                t->stime));
-                                t = next_thread(t);
-                        } while (t != tsk);
+                        struct task_cputime times;
+                        cputime_t ptime;
+
+                        thread_group_cputime(tsk, &times);
+                        ptime = cputime_add(times.utime, times.stime);
                         if (cputime_le(cval, ptime)) { /* about to fire */
                                 cval = jiffies_to_cputime(1);
                         } else {
@@ -99,7 +91,6 @@ int do_getitimer(int which, struct itimerval *value)
                         }
                 }
                 spin_unlock_irq(&tsk->sighand->siglock);
-                read_unlock(&tasklist_lock);
                 cputime_to_timeval(cval, &value->it_value);
                 cputime_to_timeval(cinterval, &value->it_interval);
                 break;
@@ -185,7 +176,6 @@ again:
         case ITIMER_VIRTUAL:
                 nval = timeval_to_cputime(&value->it_value);
                 ninterval = timeval_to_cputime(&value->it_interval);
-                read_lock(&tasklist_lock);
                 spin_lock_irq(&tsk->sighand->siglock);
                 cval = tsk->signal->it_virt_expires;
                 cinterval = tsk->signal->it_virt_incr;
@@ -200,7 +190,6 @@ again:
                 tsk->signal->it_virt_expires = nval;
                 tsk->signal->it_virt_incr = ninterval;
                 spin_unlock_irq(&tsk->sighand->siglock);
-                read_unlock(&tasklist_lock);
                 if (ovalue) {
                         cputime_to_timeval(cval, &ovalue->it_value);
                         cputime_to_timeval(cinterval, &ovalue->it_interval);
@@ -209,7 +198,6 @@ again:
         case ITIMER_PROF:
                 nval = timeval_to_cputime(&value->it_value);
                 ninterval = timeval_to_cputime(&value->it_interval);
-                read_lock(&tasklist_lock);
                 spin_lock_irq(&tsk->sighand->siglock);
                 cval = tsk->signal->it_prof_expires;
                 cinterval = tsk->signal->it_prof_incr;
@@ -224,7 +212,6 @@ again:
                 tsk->signal->it_prof_expires = nval;
                 tsk->signal->it_prof_incr = ninterval;
                 spin_unlock_irq(&tsk->sighand->siglock);
-                read_unlock(&tasklist_lock);
                 if (ovalue) {
                         cputime_to_timeval(cval, &ovalue->it_value);
                         cputime_to_timeval(cinterval, &ovalue->it_interval);