Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer updates from Thomas Gleixner:
 "The time/timekeeping/timer folks deliver with this update:

   - Fix a reintroduced signed/unsigned issue and cleanup the whole
     signed/unsigned mess in the timekeeping core so this wont happen
     accidentaly again.

   - Add a new trace clock based on boot time

   - Prevent injection of random sleep times when PM tracing abuses the
     RTC for storage

   - Make posix timers configurable for real tiny systems

   - Add tracepoints for the alarm timer subsystem so timer based
     suspend wakeups can be instrumented

   - The usual pile of fixes and updates to core and drivers"

* 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (23 commits)
  timekeeping: Use mul_u64_u32_shr() instead of open coding it
  timekeeping: Get rid of pointless typecasts
  timekeeping: Make the conversion call chain consistently unsigned
  timekeeping_Force_unsigned_clocksource_to_nanoseconds_conversion
  alarmtimer: Add tracepoints for alarm timers
  trace: Update documentation for mono, mono_raw and boot clock
  trace: Add an option for boot clock as trace clock
  timekeeping: Add a fast and NMI safe boot clock
  timekeeping/clocksource_cyc2ns: Document intended range limitation
  timekeeping: Ignore the bogus sleep time if pm_trace is enabled
  selftests/timers: Fix spelling mistake "Asyncrhonous" -> "Asynchronous"
  clocksource/drivers/bcm2835_timer: Unmap region obtained by of_iomap
  clocksource/drivers/arm_arch_timer: Map frame with of_io_request_and_map()
  arm64: dts: rockchip: Arch counter doesn't tick in system suspend
  clocksource/drivers/arm_arch_timer: Don't assume clock runs in suspend
  posix-timers: Make them configurable
  posix_cpu_timers: Move the add_device_randomness() call to a proper place
  timer: Move sys_alarm from timer.c to itimer.c
  ptp_clock: Allow for it to be optional
  Kconfig: Regenerate *.c_shipped files after previous changes
  ...

kernel/exit.c

@@ -54,6 +54,7 @@
 #include <linux/writeback.h>
 #include <linux/shm.h>
 #include <linux/kcov.h>
+#include <linux/random.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -91,11 +92,10 @@ static void __exit_signal(struct task_struct *tsk)
 					lockdep_tasklist_lock_is_held());
 	spin_lock(&sighand->siglock);
 
+#ifdef CONFIG_POSIX_TIMERS
 	posix_cpu_timers_exit(tsk);
 	if (group_dead) {
 		posix_cpu_timers_exit_group(tsk);
-		tty = sig->tty;
-		sig->tty = NULL;
 	} else {
 		/*
 		 * This can only happen if the caller is de_thread().
@@ -104,7 +104,13 @@ static void __exit_signal(struct task_struct *tsk)
 		 */
 		if (unlikely(has_group_leader_pid(tsk)))
 			posix_cpu_timers_exit_group(tsk);
+	}
+#endif
 
+	if (group_dead) {
+		tty = sig->tty;
+		sig->tty = NULL;
+	} else {
 		/*
 		 * If there is any task waiting for the group exit
 		 * then notify it:
@@ -116,6 +122,9 @@ static void __exit_signal(struct task_struct *tsk)
 			sig->curr_target = next_thread(tsk);
 	}
 
+	add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
+			      sizeof(unsigned long long));
+
 	/*
 	 * Accumulate here the counters for all threads as they die. We could
 	 * skip the group leader because it is the last user of signal_struct,
@@ -799,8 +808,10 @@ void __noreturn do_exit(long code)
 	acct_update_integrals(tsk);
 	group_dead = atomic_dec_and_test(&tsk->signal->live);
 	if (group_dead) {
+#ifdef CONFIG_POSIX_TIMERS
 		hrtimer_cancel(&tsk->signal->real_timer);
 		exit_itimers(tsk->signal);
+#endif
 		if (tsk->mm)
 			setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
 	}