hrtimer: Get rid of the resolution field in hrtimer_clock_base

commit 398ca17fb54b212cdc9da7ff4a17a35c48dd2103 upstream.

The field has no value because all clock bases have the same
resolution. The resolution only changes when we switch to high
resolution timer mode. We can evaluate that from a single static
variable as well. In the !HIGHRES case its simply a constant.

Export the variable, so we can simplify the usage sites.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/20150414203500.645454122@linutronix.de
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
[bwh: Backported to 3.16 as dependency of commit 552263456215
 "powerpc: Fix vDSO clock_getres()":
 - Adjust filename, context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index bb4ffff31c69bdd50b8a66716df6d58d5af76ff6..5306bac6aee4323efd0b27aaa7d7b795d2d5edd8 100644 (file)
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -137,7 +137,6 @@ struct hrtimer_sleeper {
  *                     timer to a base on another cpu.
  * @clockid:           clock id for per_cpu support
  * @active:            red black tree root node for the active timers
- * @resolution:                the resolution of the clock, in nanoseconds
  * @get_time:          function to retrieve the current time of the clock
  * @softirq_time:      the time when running the hrtimer queue in the softirq
  * @offset:            offset of this clock to the monotonic base
@@ -147,7 +146,6 @@ struct hrtimer_clock_base {
        int                     index;
        clockid_t               clockid;
        struct timerqueue_head  active;
-       ktime_t                 resolution;
        ktime_t                 (*get_time)(void);
        ktime_t                 softirq_time;
        ktime_t                 offset;
@@ -293,11 +291,15 @@ extern void hrtimer_peek_ahead_timers(void);
 
 extern void clock_was_set_delayed(void);
 
+extern unsigned int hrtimer_resolution;
+
 #else
 
 # define MONOTONIC_RES_NSEC    LOW_RES_NSEC
 # define KTIME_MONOTONIC_RES   KTIME_LOW_RES
 
+#define hrtimer_resolution     LOW_RES_NSEC
+
 static inline void hrtimer_peek_ahead_timers(void) { }
 
 /*

diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index aaf2b480d111274298438d798ceca44d88fb5a1d..c8faa5906f0dca2413248578988452fdf2e76a73 100644 (file)
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -64,7 +64,6 @@
  */
 DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
 {
-
        .lock = __RAW_SPIN_LOCK_UNLOCKED(hrtimer_bases.lock),
        .clock_base =
        {
@@ -72,25 +71,21 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
                        .index = HRTIMER_BASE_MONOTONIC,
                        .clockid = CLOCK_MONOTONIC,
                        .get_time = &ktime_get,
-                       .resolution = KTIME_LOW_RES,
                },
                {
                        .index = HRTIMER_BASE_REALTIME,
                        .clockid = CLOCK_REALTIME,
                        .get_time = &ktime_get_real,
-                       .resolution = KTIME_LOW_RES,
                },
                {
                        .index = HRTIMER_BASE_BOOTTIME,
                        .clockid = CLOCK_BOOTTIME,
                        .get_time = &ktime_get_boottime,
-                       .resolution = KTIME_LOW_RES,
                },
                {
                        .index = HRTIMER_BASE_TAI,
                        .clockid = CLOCK_TAI,
                        .get_time = &ktime_get_clocktai,
-                       .resolution = KTIME_LOW_RES,
                },
        }
 };
@@ -501,6 +496,8 @@ static inline void debug_deactivate(struct hrtimer *timer)
  * High resolution timer enabled ?
  */
 static int hrtimer_hres_enabled __read_mostly  = 1;
+unsigned int hrtimer_resolution __read_mostly = LOW_RES_NSEC;
+EXPORT_SYMBOL_GPL(hrtimer_resolution);
 
 /*
  * Enable / Disable high resolution mode
@@ -707,7 +704,7 @@ static void retrigger_next_event(void *arg)
  */
 static int hrtimer_switch_to_hres(void)
 {
-       int i, cpu = smp_processor_id();
+       int cpu = smp_processor_id();
        struct hrtimer_cpu_base *base = &per_cpu(hrtimer_bases, cpu);
        unsigned long flags;
 
@@ -723,8 +720,7 @@ static int hrtimer_switch_to_hres(void)
                return 0;
        }
        base->hres_active = 1;
-       for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++)
-               base->clock_base[i].resolution = KTIME_HIGH_RES;
+       hrtimer_resolution = HIGH_RES_NSEC;
 
        tick_setup_sched_timer();
        /* "Retrigger" the interrupt to get things going */
@@ -859,8 +855,8 @@ u64 hrtimer_forward(struct hrtimer *timer, ktime_t now, ktime_t interval)
        if (delta.tv64 < 0)
                return 0;
 
-       if (interval.tv64 < timer->base->resolution.tv64)
-               interval.tv64 = timer->base->resolution.tv64;
+       if (interval.tv64 < hrtimer_resolution)
+               interval.tv64 = hrtimer_resolution;
 
        if (unlikely(delta.tv64 >= interval.tv64)) {
                s64 incr = ktime_to_ns(interval);
@@ -1001,7 +997,7 @@ int __hrtimer_start_range_ns(struct hrtimer *timer, ktime_t tim,
                 * timeouts. This will go away with the GTOD framework.
                 */
 #ifdef CONFIG_TIME_LOW_RES
-               tim = ktime_add_safe(tim, base->resolution);
+               tim = ktime_add_safe(tim, ktime_set(0, hrtimer_resolution));
 #endif
        }
 
@@ -1240,12 +1236,8 @@ EXPORT_SYMBOL_GPL(hrtimer_init);
  */
 int hrtimer_get_res(const clockid_t which_clock, struct timespec *tp)
 {
-       struct hrtimer_cpu_base *cpu_base;
-       int base = hrtimer_clockid_to_base(which_clock);
-
-       cpu_base = &__raw_get_cpu_var(hrtimer_bases);
-       *tp = ktime_to_timespec(cpu_base->clock_base[base].resolution);
-
+       tp->tv_sec = 0;
+       tp->tv_nsec = hrtimer_resolution;
        return 0;
 }
 EXPORT_SYMBOL_GPL(hrtimer_get_res);

diff --git a/kernel/time/timer_list.c b/kernel/time/timer_list.c
index 37d7e4d29e5f71d7c63273dfbc9cdd5aca346f43..7e6a815aa3779bb2ac8a6e51aae0b721c9a557fc 100644 (file)
--- a/kernel/time/timer_list.c
+++ b/kernel/time/timer_list.c
@@ -120,10 +120,10 @@ static void
 print_base(struct seq_file *m, struct hrtimer_clock_base *base, u64 now)
 {
        SEQ_printf(m, "  .base:       %pK\n", base);
-       SEQ_printf(m, "  .index:      %d\n",
-                       base->index);
-       SEQ_printf(m, "  .resolution: %Lu nsecs\n",
-                       (unsigned long long)ktime_to_ns(base->resolution));
+       SEQ_printf(m, "  .index:      %d\n", base->index);
+
+       SEQ_printf(m, "  .resolution: %u nsecs\n", (unsigned) hrtimer_resolution);
+
        SEQ_printf(m,   "  .get_time:   ");
        print_name_offset(m, base->get_time);
        SEQ_printf(m,   "\n");