timers: Remove must_forward_clk

There is no reason to keep this guard around. The code makes sure that
base->clk remains sane and won't be forwarded beyond jiffies nor set
backward.

Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://lkml.kernel.org/r/20200717140551.29076-12-frederic@kernel.org

diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index 4f78a7bff9e19078871a9ea225cf2b8094258ccd..8b3fb52d8c4793deae2ce7bf9d6e332c17ee0f3e 100644 (file)
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -205,7 +205,6 @@ struct timer_base {
        unsigned long           next_expiry;
        unsigned int            cpu;
        bool                    is_idle;
-       bool                    must_forward_clk;
        DECLARE_BITMAP(pending_map, WHEEL_SIZE);
        struct hlist_head       vectors[WHEEL_SIZE];
 } ____cacheline_aligned;
@@ -888,12 +887,13 @@ get_target_base(struct timer_base *base, unsigned tflags)
 
 static inline void forward_timer_base(struct timer_base *base)
 {
-       unsigned long jnow;
+       unsigned long jnow = READ_ONCE(jiffies);
 
-       if (!base->must_forward_clk)
-               return;
-
-       jnow = READ_ONCE(jiffies);
+       /*
+        * No need to forward if we are close enough below jiffies.
+        * Also while executing timers, base->clk is 1 offset ahead
+        * of jiffies to avoid endless requeuing to current jffies.
+        */
        if ((long)(jnow - base->clk) < 2)
                return;
 
@@ -1722,16 +1722,8 @@ static inline void __run_timers(struct timer_base *base)
        timer_base_lock_expiry(base);
        raw_spin_lock_irq(&base->lock);
 
-       /*
-        * timer_base::must_forward_clk must be cleared before running
-        * timers so that any timer functions that call mod_timer() will
-        * not try to forward the base.
-        */
-       base->must_forward_clk = false;
-
        while (time_after_eq(jiffies, base->clk) &&
               time_after_eq(jiffies, base->next_expiry)) {
-
                levels = collect_expired_timers(base, heads);
                base->clk++;
                base->next_expiry = __next_timer_interrupt(base);
@@ -1739,7 +1731,6 @@ static inline void __run_timers(struct timer_base *base)
                while (levels--)
                        expire_timers(base, heads + levels);
        }
-       base->must_forward_clk = true;
        raw_spin_unlock_irq(&base->lock);
        timer_base_unlock_expiry(base);
 }
@@ -1935,7 +1926,6 @@ int timers_prepare_cpu(unsigned int cpu)
                base->clk = jiffies;
                base->next_expiry = base->clk + NEXT_TIMER_MAX_DELTA;
                base->is_idle = false;
-               base->must_forward_clk = true;
        }
        return 0;
 }