hrtimers: Avoid touching inactive timer bases

Instead of iterating over all possible timer bases avoid it by marking
the active bases in the cpu base.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>

6 files changed, 29 insertions, 19 deletions

diff --git a/include/linux/hrtimer.h b/include/linux/hrtimer.h
index cc5f5f51db10..771c95802edc 100644
--- a/include/linux/hrtimer.h
+++ b/include/linux/hrtimer.h
@@ -143,7 +143,8 @@ struct hrtimer_sleeper {
  */
 struct hrtimer_clock_base {
         struct hrtimer_cpu_base *cpu_base;
-        clockid_t               index;
+        int                     index;
+        clockid_t               clockid;
         struct timerqueue_head  active;
         ktime_t                 resolution;
         ktime_t                 (*get_time)(void);
@@ -162,7 +163,7 @@ enum  hrtimer_base_type {
  * struct hrtimer_cpu_base - the per cpu clock bases
  * @lock:               lock protecting the base and associated clock bases
  *                      and timers
- * @clock_base:         array of clock bases for this cpu
+ * @active_bases:       Bitfield to mark bases with active timers
  * @expires_next:       absolute time of the next event which was scheduled
  *                      via clock_set_next_event()
  * @hres_active:        State of high resolution mode
@@ -171,9 +172,11 @@ enum  hrtimer_base_type {
  * @nr_retries:         Total number of hrtimer interrupt retries
  * @nr_hangs:           Total number of hrtimer interrupt hangs
  * @max_hang_time:      Maximum time spent in hrtimer_interrupt
+ * @clock_base:         array of clock bases for this cpu
  */
 struct hrtimer_cpu_base {
         raw_spinlock_t                  lock;
+        unsigned long                   active_bases;
 #ifdef CONFIG_HIGH_RES_TIMERS
         ktime_t                         expires_next;
         int                             hres_active;
diff --git a/include/linux/thread_info.h b/include/linux/thread_info.h
index 20fc303947d3..8d03f079688c 100644
--- a/include/linux/thread_info.h
+++ b/include/linux/thread_info.h
@@ -29,7 +29,7 @@ struct restart_block {
                 } futex;
                 /* For nanosleep */
                 struct {
-                        clockid_t index;
+                        clockid_t clockid;
                         struct timespec __user *rmtp;
 #ifdef CONFIG_COMPAT
                         struct compat_timespec __user *compat_rmtp;
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index 26dd32f9f6b2..1b08f6d67f12 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -64,17 +64,20 @@ DEFINE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases) =
         .clock_base =
         {
                 {
-                        .index = CLOCK_REALTIME,
+                        .index = HRTIMER_BASE_REALTIME,
+                        .clockid = CLOCK_REALTIME,
                         .get_time = &ktime_get_real,
                         .resolution = KTIME_LOW_RES,
                 },
                 {
-                        .index = CLOCK_MONOTONIC,
+                        .index = HRTIMER_BASE_MONOTONIC,
+                        .clockid = CLOCK_MONOTONIC,
                         .get_time = &ktime_get,
                         .resolution = KTIME_LOW_RES,
                 },
                 {
-                        .index = CLOCK_BOOTTIME,
+                        .index = HRTIMER_BASE_BOOTTIME,
+                        .clockid = CLOCK_BOOTTIME,
                         .get_time = &ktime_get_boottime,
                         .resolution = KTIME_LOW_RES,
                 },
@@ -196,7 +199,7 @@ switch_hrtimer_base(struct hrtimer *timer, struct hrtimer_clock_base *base,
         struct hrtimer_cpu_base *new_cpu_base;
         int this_cpu = smp_processor_id();
         int cpu = hrtimer_get_target(this_cpu, pinned);
-        int basenum = hrtimer_clockid_to_base(base->index);
+        int basenum = base->index;
 
 again:
         new_cpu_base = &per_cpu(hrtimer_bases, cpu);
@@ -857,6 +860,7 @@ static int enqueue_hrtimer(struct hrtimer *timer,
         debug_activate(timer);
 
         timerqueue_add(&base->active, &timer->node);
+        base->cpu_base->active_bases |= 1 << base->index;
 
         /*
          * HRTIMER_STATE_ENQUEUED is or'ed to the current state to preserve the
@@ -898,6 +902,8 @@ static void __remove_hrtimer(struct hrtimer *timer,
 #endif
         }
         timerqueue_del(&base->active, &timer->node);
+        if (!timerqueue_getnext(&base->active))
+                base->cpu_base->active_bases &= ~(1 << base->index);
 out:
         timer->state = newstate;
 }
@@ -1235,7 +1241,6 @@ static void __run_hrtimer(struct hrtimer *timer, ktime_t *now)
 void hrtimer_interrupt(struct clock_event_device *dev)
 {
         struct hrtimer_cpu_base *cpu_base = &__get_cpu_var(hrtimer_bases);
-        struct hrtimer_clock_base *base;
         ktime_t expires_next, now, entry_time, delta;
         int i, retries = 0;
 
@@ -1257,12 +1262,15 @@ retry:
          */
         cpu_base->expires_next.tv64 = KTIME_MAX;
 
-        base = cpu_base->clock_base;
-
         for (i = 0; i < HRTIMER_MAX_CLOCK_BASES; i++) {
-                ktime_t basenow;
+                struct hrtimer_clock_base *base;
                 struct timerqueue_node *node;
+                ktime_t basenow;
+
+                if (!(cpu_base->active_bases & (1 << i)))
+                        continue;
 
+                base = cpu_base->clock_base + i;
                 basenow = ktime_add(now, base->offset);
 
                 while ((node = timerqueue_getnext(&base->active))) {
@@ -1295,7 +1303,6 @@ retry:
 
                         __run_hrtimer(timer, &basenow);
                 }
-                base++;
         }
 
         /*
@@ -1526,7 +1533,7 @@ long __sched hrtimer_nanosleep_restart(struct restart_block *restart)
         struct timespec __user  *rmtp;
         int ret = 0;
 
-        hrtimer_init_on_stack(&t.timer, restart->nanosleep.index,
+        hrtimer_init_on_stack(&t.timer, restart->nanosleep.clockid,
                                 HRTIMER_MODE_ABS);
         hrtimer_set_expires_tv64(&t.timer, restart->nanosleep.expires);
 
@@ -1578,7 +1585,7 @@ long hrtimer_nanosleep(struct timespec *rqtp, struct timespec __user *rmtp,
 
         restart = &current_thread_info()->restart_block;
         restart->fn = hrtimer_nanosleep_restart;
-        restart->nanosleep.index = t.timer.base->index;
+        restart->nanosleep.clockid = t.timer.base->clockid;
         restart->nanosleep.rmtp = rmtp;
         restart->nanosleep.expires = hrtimer_get_expires_tv64(&t.timer);
 
diff --git a/kernel/posix-cpu-timers.c b/kernel/posix-cpu-timers.c
index 0791b13df7bf..58f405b581e7 100644
--- a/kernel/posix-cpu-timers.c
+++ b/kernel/posix-cpu-timers.c
@@ -1514,7 +1514,7 @@ static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
                         return -EFAULT;
 
                 restart_block->fn = posix_cpu_nsleep_restart;
-                restart_block->nanosleep.index = which_clock;
+                restart_block->nanosleep.clockid = which_clock;
                 restart_block->nanosleep.rmtp = rmtp;
                 restart_block->nanosleep.expires = timespec_to_ns(rqtp);
         }
@@ -1523,7 +1523,7 @@ static int posix_cpu_nsleep(const clockid_t which_clock, int flags,
 
 static long posix_cpu_nsleep_restart(struct restart_block *restart_block)
 {
-        clockid_t which_clock = restart_block->nanosleep.index;
+        clockid_t which_clock = restart_block->nanosleep.clockid;
         struct timespec t;
         struct itimerspec it;
         int error;
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index e5498d7405c3..a1b5edf1bf92 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -1056,7 +1056,7 @@ SYSCALL_DEFINE4(clock_nanosleep, const clockid_t, which_clock, int, flags,
  */
 long clock_nanosleep_restart(struct restart_block *restart_block)
 {
-        clockid_t which_clock = restart_block->nanosleep.index;
+        clockid_t which_clock = restart_block->nanosleep.clockid;
         struct k_clock *kc = clockid_to_kclock(which_clock);
 
         if (WARN_ON_ONCE(!kc || !kc->nsleep_restart))
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c
index c6027fe9a4e6..2d966244ea60 100644
--- a/kernel/time/alarmtimer.c
+++ b/kernel/time/alarmtimer.c
@@ -494,7 +494,7 @@ static int update_rmtp(ktime_t exp, enum  alarmtimer_type type,
  */
 static long __sched alarm_timer_nsleep_restart(struct restart_block *restart)
 {
-        enum  alarmtimer_type type = restart->nanosleep.index;
+        enum  alarmtimer_type type = restart->nanosleep.clockid;
         ktime_t exp;
         struct timespec __user  *rmtp;
         struct alarm alarm;
@@ -573,7 +573,7 @@ static int alarm_timer_nsleep(const clockid_t which_clock, int flags,
 
         restart = &current_thread_info()->restart_block;
         restart->fn = alarm_timer_nsleep_restart;
-        restart->nanosleep.index = type;
+        restart->nanosleep.clockid = type;
         restart->nanosleep.expires = exp.tv64;
         restart->nanosleep.rmtp = rmtp;
         ret = -ERESTART_RESTARTBLOCK;