hrtimer: Unconfuse switch_hrtimer_base() a bit

The variable called "this_base" is confusing because its name suggests
it's of "struct hrtimer_clock_base" type, along with "base" and "new_base"
which doesn't help understanding this complicated function.

Make its name clearer and fix the misleading comment while at it.

[ tglx: Fixed the comment for real ]

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1439907509-9553-3-git-send-email-fweisbec@gmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c
index f9eb21b..5c4fe50 100644 (file)
--- a/kernel/time/hrtimer.c
+++ b/kernel/time/hrtimer.c
@@ -196,18 +196,27 @@ struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base,
 #endif
 
 /*
- * Switch the timer base to the current CPU when possible.
+ * We switch the timer base to a power-optimized selected CPU target,
+ * if:
+ *     - NO_HZ_COMMON is enabled
+ *     - timer migration is enabled
+ *     - the timer callback is not running
+ *     - the timer is not the first expiring timer on the new target
+ *
+ * If one of the above requirements is not fulfilled we move the timer
+ * to the current CPU or leave it on the previously assigned CPU if
+ * the timer callback is currently running.
  */
 static inline struct hrtimer_clock_base *
 switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
                    int pinned)
 {
-       struct hrtimer_cpu_base *new_cpu_base, *this_base;
+       struct hrtimer_cpu_base *new_cpu_base, *this_cpu_base;
        struct hrtimer_clock_base *new_base;
        int basenum = base->index;
 
-       this_base = this_cpu_ptr(&hrtimer_bases);
-       new_cpu_base = get_target_base(this_base, pinned);
+       this_cpu_base = this_cpu_ptr(&hrtimer_bases);
+       new_cpu_base = get_target_base(this_cpu_base, pinned);
 again:
        new_base = &new_cpu_base->clock_base[basenum];
 
@@ -229,19 +238,19 @@ again:
                raw_spin_unlock(&base->cpu_base->lock);
                raw_spin_lock(&new_base->cpu_base->lock);
 
-               if (new_cpu_base != this_base &&
+               if (new_cpu_base != this_cpu_base &&
                    hrtimer_check_target(timer, new_base)) {
                        raw_spin_unlock(&new_base->cpu_base->lock);
                        raw_spin_lock(&base->cpu_base->lock);
-                       new_cpu_base = this_base;
+                       new_cpu_base = this_cpu_base;
                        timer->base = base;
                        goto again;
                }
                timer->base = new_base;
        } else {
-               if (new_cpu_base != this_base &&
+               if (new_cpu_base != this_cpu_base &&
                    hrtimer_check_target(timer, new_base)) {
-                       new_cpu_base = this_base;
+                       new_cpu_base = this_cpu_base;
                        goto again;
                }
        }