Merge tag 'driver-core-4.9-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git...

[cascardo/linux.git] / kernel / time / timer.c

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index ccf9130..c611c47 100644 (file)
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -878,7 +878,7 @@ static inline struct timer_base *get_timer_base(u32 tflags)
 
 #ifdef CONFIG_NO_HZ_COMMON
 static inline struct timer_base *
-__get_target_base(struct timer_base *base, unsigned tflags)
+get_target_base(struct timer_base *base, unsigned tflags)
 {
 #ifdef CONFIG_SMP
        if ((tflags & TIMER_PINNED) || !base->migration_enabled)
@@ -891,25 +891,27 @@ __get_target_base(struct timer_base *base, unsigned tflags)
 
 static inline void forward_timer_base(struct timer_base *base)
 {
+       unsigned long jnow = READ_ONCE(jiffies);
+
        /*
         * We only forward the base when it's idle and we have a delta between
         * base clock and jiffies.
         */
-       if (!base->is_idle || (long) (jiffies - base->clk) < 2)
+       if (!base->is_idle || (long) (jnow - base->clk) < 2)
                return;
 
        /*
         * If the next expiry value is > jiffies, then we fast forward to
         * jiffies otherwise we forward to the next expiry value.
         */
-       if (time_after(base->next_expiry, jiffies))
-               base->clk = jiffies;
+       if (time_after(base->next_expiry, jnow))
+               base->clk = jnow;
        else
                base->clk = base->next_expiry;
 }
 #else
 static inline struct timer_base *
-__get_target_base(struct timer_base *base, unsigned tflags)
+get_target_base(struct timer_base *base, unsigned tflags)
 {
        return get_timer_this_cpu_base(tflags);
 }
@@ -917,14 +919,6 @@ __get_target_base(struct timer_base *base, unsigned tflags)
 static inline void forward_timer_base(struct timer_base *base) { }
 #endif
 
-static inline struct timer_base *
-get_target_base(struct timer_base *base, unsigned tflags)
-{
-       struct timer_base *target = __get_target_base(base, tflags);
-
-       forward_timer_base(target);
-       return target;
-}
 
 /*
  * We are using hashed locking: Holding per_cpu(timer_bases[x]).lock means
@@ -1037,6 +1031,9 @@ __mod_timer(struct timer_list *timer, unsigned long expires, bool pending_only)
                }
        }
 
+       /* Try to forward a stale timer base clock */
+       forward_timer_base(base);
+
        timer->expires = expires;
        /*
         * If 'idx' was calculated above and the base time did not advance
@@ -1523,12 +1520,16 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
        is_max_delta = (nextevt == base->clk + NEXT_TIMER_MAX_DELTA);
        base->next_expiry = nextevt;
        /*
-        * We have a fresh next event. Check whether we can forward the base:
+        * We have a fresh next event. Check whether we can forward the
+        * base. We can only do that when @basej is past base->clk
+        * otherwise we might rewind base->clk.
         */
-       if (time_after(nextevt, jiffies))
-               base->clk = jiffies;
-       else if (time_after(nextevt, base->clk))
-               base->clk = nextevt;
+       if (time_after(basej, base->clk)) {
+               if (time_after(nextevt, basej))
+                       base->clk = basej;
+               else if (time_after(nextevt, base->clk))
+                       base->clk = nextevt;
+       }
 
        if (time_before_eq(nextevt, basej)) {
                expires = basem;