hrtimer: Implement SOFT/HARD clock base selection

All prerequisites to handle hrtimers for expiry in either hard or soft
interrupt context are in place.

Add the missing bit in hrtimer_init() which associates the timer to the
hard or the softirq clock base.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-30-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/time/hrtimer.c

@@ -1220,8 +1220,9 @@ static inline int hrtimer_clockid_to_base(clockid_t clock_id)
 static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 			   enum hrtimer_mode mode)
 {
+	bool softtimer = !!(mode & HRTIMER_MODE_SOFT);
+	int base = softtimer ? HRTIMER_MAX_CLOCK_BASES / 2 : 0;
 	struct hrtimer_cpu_base *cpu_base;
-	int base;
 
 	memset(timer, 0, sizeof(struct hrtimer));
 
@@ -1235,7 +1236,8 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 	if (clock_id == CLOCK_REALTIME && mode & HRTIMER_MODE_REL)
 		clock_id = CLOCK_MONOTONIC;
 
-	base = hrtimer_clockid_to_base(clock_id);
+	base += hrtimer_clockid_to_base(clock_id);
+	timer->is_soft = softtimer;
 	timer->base = &cpu_base->clock_base[base];
 	timerqueue_init(&timer->node);
 }
@@ -1244,8 +1246,13 @@ static void __hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
  * hrtimer_init - initialize a timer to the given clock
  * @timer:	the timer to be initialized
  * @clock_id:	the clock to be used
- * @mode:	timer mode: absolute (HRTIMER_MODE_ABS) or
- *		relative (HRTIMER_MODE_REL); pinned is not considered here!
+ * @mode:       The modes which are relevant for intitialization:
+ *              HRTIMER_MODE_ABS, HRTIMER_MODE_REL, HRTIMER_MODE_ABS_SOFT,
+ *              HRTIMER_MODE_REL_SOFT
+ *
+ *              The PINNED variants of the above can be handed in,
+ *              but the PINNED bit is ignored as pinning happens
+ *              when the hrtimer is started
  */
 void hrtimer_init(struct hrtimer *timer, clockid_t clock_id,
 		  enum hrtimer_mode mode)