6 files changed, 69 insertions, 25 deletions

diff --git a/fs/proc/array.c b/fs/proc/array.c
index ca61a88aed66..2571da43c736 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -506,7 +506,6 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 
                 /* add up live thread stats at the group level */
                 if (whole) {
-                        struct task_cputime cputime;
                         struct task_struct *t = task;
                         do {
                                 min_flt += t->min_flt;
@@ -517,9 +516,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
 
                         min_flt += sig->min_flt;
                         maj_flt += sig->maj_flt;
-                        thread_group_cputime(task, &cputime);
-                        utime = cputime.utime;
-                        stime = cputime.stime;
+                        thread_group_times(task, &utime, &stime);
                         gtime = cputime_add(gtime, sig->gtime);
                 }
 
diff --git a/include/linux/sched.h b/include/linux/sched.h
index dff85e58264e..34238bd10ebf 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -624,6 +624,9 @@ struct signal_struct {
         cputime_t utime, stime, cutime, cstime;
         cputime_t gtime;
         cputime_t cgtime;
+#ifndef CONFIG_VIRT_CPU_ACCOUNTING
+        cputime_t prev_utime, prev_stime;
+#endif
         unsigned long nvcsw, nivcsw, cnvcsw, cnivcsw;
         unsigned long min_flt, maj_flt, cmin_flt, cmaj_flt;
         unsigned long inblock, oublock, cinblock, coublock;
@@ -1723,6 +1726,7 @@ static inline void put_task_struct(struct task_struct *t)
 }
 
 extern void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st);
+extern void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st);
 
 /*
  * Per process flags
diff --git a/kernel/exit.c b/kernel/exit.c
index 2eaf68b634e3..b221ad65fd20 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -91,8 +91,6 @@ static void __exit_signal(struct task_struct *tsk)
         if (atomic_dec_and_test(&sig->count))
                 posix_cpu_timers_exit_group(tsk);
         else {
-                cputime_t utime, stime;
-
                 /*
                  * If there is any task waiting for the group exit
                  * then notify it:
@@ -112,9 +110,8 @@ static void __exit_signal(struct task_struct *tsk)
                  * We won't ever get here for the group leader, since it
                  * will have been the last reference on the signal_struct.
                  */
-                task_times(tsk, &utime, &stime);
-                sig->utime = cputime_add(sig->utime, utime);
-                sig->stime = cputime_add(sig->stime, stime);
+                sig->utime = cputime_add(sig->utime, tsk->utime);
+                sig->stime = cputime_add(sig->stime, tsk->stime);
                 sig->gtime = cputime_add(sig->gtime, tsk->gtime);
                 sig->min_flt += tsk->min_flt;
                 sig->maj_flt += tsk->maj_flt;
@@ -1208,6 +1205,7 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
                 struct signal_struct *psig;
                 struct signal_struct *sig;
                 unsigned long maxrss;
+                cputime_t tgutime, tgstime;
 
                 /*
                  * The resource counters for the group leader are in its
@@ -1223,20 +1221,23 @@ static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
                  * need to protect the access to parent->signal fields,
                  * as other threads in the parent group can be right
                  * here reaping other children at the same time.
+                 *
+                 * We use thread_group_times() to get times for the thread
+                 * group, which consolidates times for all threads in the
+                 * group including the group leader.
                  */
+                thread_group_times(p, &tgutime, &tgstime);
                 spin_lock_irq(&p->real_parent->sighand->siglock);
                 psig = p->real_parent->signal;
                 sig = p->signal;
                 psig->cutime =
                         cputime_add(psig->cutime,
-                        cputime_add(p->utime,
-                        cputime_add(sig->utime,
-                                    sig->cutime)));
+                        cputime_add(tgutime,
+                                    sig->cutime));
                 psig->cstime =
                         cputime_add(psig->cstime,
-                        cputime_add(p->stime,
-                        cputime_add(sig->stime,
-                                    sig->cstime)));
+                        cputime_add(tgstime,
+                                    sig->cstime));
                 psig->cgtime =
                         cputime_add(psig->cgtime,
                         cputime_add(p->gtime,
diff --git a/kernel/fork.c b/kernel/fork.c
index ad7cb6d1193c..3d6f121bbe8a 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -884,6 +884,9 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk)
         sig->utime = sig->stime = sig->cutime = sig->cstime = cputime_zero;
         sig->gtime = cputime_zero;
         sig->cgtime = cputime_zero;
+#ifndef CONFIG_VIRT_CPU_ACCOUNTING
+        sig->prev_utime = sig->prev_stime = cputime_zero;
+#endif
         sig->nvcsw = sig->nivcsw = sig->cnvcsw = sig->cnivcsw = 0;
         sig->min_flt = sig->maj_flt = sig->cmin_flt = sig->cmaj_flt = 0;
         sig->inblock = sig->oublock = sig->cinblock = sig->coublock = 0;
diff --git a/kernel/sched.c b/kernel/sched.c
index 17e2c1db2bde..e6ba726941ae 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5187,6 +5187,16 @@ void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
         *ut = p->utime;
         *st = p->stime;
 }
+
+void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
+{
+        struct task_cputime cputime;
+
+        thread_group_cputime(p, &cputime);
+
+        *ut = cputime.utime;
+        *st = cputime.stime;
+}
 #else
 
 #ifndef nsecs_to_cputime
@@ -5220,6 +5230,37 @@ void task_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
         *ut = p->prev_utime;
         *st = p->prev_stime;
 }
+
+/*
+ * Must be called with siglock held.
+ */
+void thread_group_times(struct task_struct *p, cputime_t *ut, cputime_t *st)
+{
+        struct signal_struct *sig = p->signal;
+        struct task_cputime cputime;
+        cputime_t rtime, utime, total;
+
+        thread_group_cputime(p, &cputime);
+
+        total = cputime_add(cputime.utime, cputime.stime);
+        rtime = nsecs_to_cputime(cputime.sum_exec_runtime);
+
+        if (total) {
+                u64 temp;
+
+                temp = (u64)(rtime * cputime.utime);
+                do_div(temp, total);
+                utime = (cputime_t)temp;
+        } else
+                utime = rtime;
+
+        sig->prev_utime = max(sig->prev_utime, utime);
+        sig->prev_stime = max(sig->prev_stime,
+                              cputime_sub(rtime, sig->prev_utime));
+
+        *ut = sig->prev_utime;
+        *st = sig->prev_stime;
+}
 #endif
 
 /*
diff --git a/kernel/sys.c b/kernel/sys.c
index bbdfce0d4347..9968c5fb55b9 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -911,16 +911,15 @@ change_okay:
 
 void do_sys_times(struct tms *tms)
 {
-        struct task_cputime cputime;
-        cputime_t cutime, cstime;
+        cputime_t tgutime, tgstime, cutime, cstime;
 
-        thread_group_cputime(current, &cputime);
         spin_lock_irq(&current->sighand->siglock);
+        thread_group_times(current, &tgutime, &tgstime);
         cutime = current->signal->cutime;
         cstime = current->signal->cstime;
         spin_unlock_irq(&current->sighand->siglock);
-        tms->tms_utime = cputime_to_clock_t(cputime.utime);
-        tms->tms_stime = cputime_to_clock_t(cputime.stime);
+        tms->tms_utime = cputime_to_clock_t(tgutime);
+        tms->tms_stime = cputime_to_clock_t(tgstime);
         tms->tms_cutime = cputime_to_clock_t(cutime);
         tms->tms_cstime = cputime_to_clock_t(cstime);
 }
@@ -1338,8 +1337,7 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
 {
         struct task_struct *t;
         unsigned long flags;
-        cputime_t utime, stime;
-        struct task_cputime cputime;
+        cputime_t tgutime, tgstime, utime, stime;
         unsigned long maxrss = 0;
 
         memset((char *) r, 0, sizeof *r);
@@ -1372,9 +1370,9 @@ static void k_getrusage(struct task_struct *p, int who, struct rusage *r)
                                 break;
 
                 case RUSAGE_SELF:
-                        thread_group_cputime(p, &cputime);
-                        utime = cputime_add(utime, cputime.utime);
-                        stime = cputime_add(stime, cputime.stime);
+                        thread_group_times(p, &tgutime, &tgstime);
+                        utime = cputime_add(utime, tgutime);
+                        stime = cputime_add(stime, tgstime);
                         r->ru_nvcsw += p->signal->nvcsw;
                         r->ru_nivcsw += p->signal->nivcsw;
                         r->ru_minflt += p->signal->min_flt;