1 files changed, 21 insertions, 3 deletions

diff --git a/kernel/itimer.c b/kernel/itimer.c
index 852c88ddd1f0..21adff7b2a17 100644
--- a/kernel/itimer.c
+++ b/kernel/itimer.c
@@ -42,7 +42,7 @@ static struct timeval itimer_get_remtime(struct hrtimer *timer)
 }
 
 static void get_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
-                           struct itimerval *value)
+                           struct itimerval *const value)
 {
         cputime_t cval, cinterval;
         struct cpu_itimer *it = &tsk->signal->it[clock_id];
@@ -127,14 +127,32 @@ enum hrtimer_restart it_real_fn(struct hrtimer *timer)
         return HRTIMER_NORESTART;
 }
 
+static inline u32 cputime_sub_ns(cputime_t ct, s64 real_ns)
+{
+        struct timespec ts;
+        s64 cpu_ns;
+
+        cputime_to_timespec(ct, &ts);
+        cpu_ns = timespec_to_ns(&ts);
+
+        return (cpu_ns <= real_ns) ? 0 : cpu_ns - real_ns;
+}
+
 static void set_cpu_itimer(struct task_struct *tsk, unsigned int clock_id,
-                           struct itimerval *value, struct itimerval *ovalue)
+                           const struct itimerval *const value,
+                           struct itimerval *const ovalue)
 {
-        cputime_t cval, cinterval, nval, ninterval;
+        cputime_t cval, nval, cinterval, ninterval;
+        s64 ns_ninterval, ns_nval;
         struct cpu_itimer *it = &tsk->signal->it[clock_id];
 
         nval = timeval_to_cputime(&value->it_value);
+        ns_nval = timeval_to_ns(&value->it_value);
         ninterval = timeval_to_cputime(&value->it_interval);
+        ns_ninterval = timeval_to_ns(&value->it_interval);
+
+        it->incr_error = cputime_sub_ns(ninterval, ns_ninterval);
+        it->error = cputime_sub_ns(nval, ns_nval);
 
         spin_lock_irq(&tsk->sighand->siglock);