1 files changed, 33 insertions, 2 deletions

diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 588c99da0307..329ce0172074 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -353,9 +353,40 @@ static enum hrtimer_restart posix_timer_fn(struct hrtimer *timer)
                  * it should be restarted.
                  */
                 if (timr->it.real.interval.tv64 != 0) {
+                        ktime_t now = hrtimer_cb_get_time(timer);
+
+                        /*
+                         * FIXME: What we really want, is to stop this
+                         * timer completely and restart it in case the
+                         * SIG_IGN is removed. This is a non trivial
+                         * change which involves sighand locking
+                         * (sigh !), which we don't want to do late in
+                         * the release cycle.
+                         *
+                         * For now we just let timers with an interval
+                         * less than a jiffie expire every jiffie to
+                         * avoid softirq starvation in case of SIG_IGN
+                         * and a very small interval, which would put
+                         * the timer right back on the softirq pending
+                         * list. By moving now ahead of time we trick
+                         * hrtimer_forward() to expire the timer
+                         * later, while we still maintain the overrun
+                         * accuracy, but have some inconsistency in
+                         * the timer_gettime() case. This is at least
+                         * better than a starved softirq. A more
+                         * complex fix which solves also another related
+                         * inconsistency is already in the pipeline.
+                         */
+#ifdef CONFIG_HIGH_RES_TIMERS
+                        {
+                                ktime_t kj = ktime_set(0, NSEC_PER_SEC / HZ);
+
+                                if (timr->it.real.interval.tv64 < kj.tv64)
+                                        now = ktime_add(now, kj);
+                        }
+#endif
                         timr->it_overrun +=
-                                hrtimer_forward(timer,
-                                                hrtimer_cb_get_time(timer),
+                                hrtimer_forward(timer, now,
                                                 timr->it.real.interval);
                         ret = HRTIMER_RESTART;
                         ++timr->it_requeue_pending;