Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer fixes from Thomas Gleixner:
 "This update brings along:

   - Two fixes for long standing bugs in the hrtimer code, one which
     prevents remote enqueuing and the other preventing arbitrary delays
     after a interrupt hang was detected

   - A fix in the timer wheel which prevents math overflow

   - A fix for a long standing issue with the architected ARM timer
     related to the C3STOP mechanism.

   - A trivial compile fix for nspire SoC clocksource"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timer: Prevent overflow in apply_slack
  hrtimer: Prevent remote enqueue of leftmost timers
  hrtimer: Prevent all reprogramming if hang detected
  clocksource: nspire: Fix compiler warning
  clocksource: arch_arm_timer: Fix age-old arch timer C3STOP detection issue

5 files changed, 37 insertions, 3 deletions

diff --git a/Documentation/devicetree/bindings/arm/arch_timer.txt b/Documentation/devicetree/bindings/arm/arch_timer.txt
index 06fc7602593a..37b2cafa4e52 100644
--- a/Documentation/devicetree/bindings/arm/arch_timer.txt
+++ b/Documentation/devicetree/bindings/arm/arch_timer.txt
@@ -19,6 +19,9 @@ to deliver its interrupts via SPIs.
 
 - clock-frequency : The frequency of the main counter, in Hz. Optional.
 
+- always-on : a boolean property. If present, the timer is powered through an
+  always-on power domain, therefore it never loses context.
+
 Example:
 
         timer {
diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
index 57e823c44d2a..5163ec13429d 100644
--- a/drivers/clocksource/arm_arch_timer.c
+++ b/drivers/clocksource/arm_arch_timer.c
@@ -66,6 +66,7 @@ static int arch_timer_ppi[MAX_TIMER_PPI];
 static struct clock_event_device __percpu *arch_timer_evt;
 
 static bool arch_timer_use_virtual = true;
+static bool arch_timer_c3stop;
 static bool arch_timer_mem_use_virtual;
 
 /*
@@ -263,7 +264,8 @@ static void __arch_timer_setup(unsigned type,
         clk->features = CLOCK_EVT_FEAT_ONESHOT;
 
         if (type == ARCH_CP15_TIMER) {
-                clk->features |= CLOCK_EVT_FEAT_C3STOP;
+                if (arch_timer_c3stop)
+                        clk->features |= CLOCK_EVT_FEAT_C3STOP;
                 clk->name = "arch_sys_timer";
                 clk->rating = 450;
                 clk->cpumask = cpumask_of(smp_processor_id());
@@ -665,6 +667,8 @@ static void __init arch_timer_init(struct device_node *np)
                 }
         }
 
+        arch_timer_c3stop = !of_property_read_bool(np, "always-on");
+
         arch_timer_register();
         arch_timer_common_init();
 }
diff --git a/drivers/clocksource/zevio-timer.c b/drivers/clocksource/zevio-timer.c
index ca81809d159d..7ce442148c3f 100644
--- a/drivers/clocksource/zevio-timer.c
+++ b/drivers/clocksource/zevio-timer.c
@@ -212,4 +212,9 @@ error_free:
         return ret;
 }
 
-CLOCKSOURCE_OF_DECLARE(zevio_timer, "lsi,zevio-timer", zevio_timer_add);
+static void __init zevio_timer_init(struct device_node *node)
+{
+        BUG_ON(zevio_timer_add(node));
+}
+
+CLOCKSOURCE_OF_DECLARE(zevio_timer, "lsi,zevio-timer", zevio_timer_init);
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index d55092ceee29..6b715c0af1b1 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -234,6 +234,11 @@ again:
                         goto again;
                 }
                 timer->base = new_base;
+        } else {
+                if (cpu != this_cpu && hrtimer_check_target(timer, new_base)) {
+                        cpu = this_cpu;
+                        goto again;
+                }
         }
         return new_base;
 }
@@ -569,6 +574,23 @@ hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal)
 
         cpu_base->expires_next.tv64 = expires_next.tv64;
 
+        /*
+         * If a hang was detected in the last timer interrupt then we
+         * leave the hang delay active in the hardware. We want the
+         * system to make progress. That also prevents the following
+         * scenario:
+         * T1 expires 50ms from now
+         * T2 expires 5s from now
+         *
+         * T1 is removed, so this code is called and would reprogram
+         * the hardware to 5s from now. Any hrtimer_start after that
+         * will not reprogram the hardware due to hang_detected being
+         * set. So we'd effectivly block all timers until the T2 event
+         * fires.
+         */
+        if (cpu_base->hang_detected)
+                return;
+
         if (cpu_base->expires_next.tv64 != KTIME_MAX)
                 tick_program_event(cpu_base->expires_next, 1);
 }
diff --git a/kernel/timer.c b/kernel/timer.c
index 87bd529879c2..3bb01a323b2a 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -838,7 +838,7 @@ unsigned long apply_slack(struct timer_list *timer, unsigned long expires)
 
         bit = find_last_bit(&mask, BITS_PER_LONG);
 
-        mask = (1 << bit) - 1;
+        mask = (1UL << bit) - 1;
 
         expires_limit = expires_limit & ~(mask);