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

Pull timer fixes from Thomas Gleixner:
 "A pile of fixes for long standing issues with the timer wheel and the
  NOHZ code:

   - Prevent timer base confusion accross the nohz switch, which can
     cause unlocked access and data corruption

   - Reinitialize the stale base clock on cpu hotplug to prevent subtle
     side effects including rollovers on 32bit

   - Prevent an interrupt storm when the timer softirq is already
     pending caused by tick_nohz_stop_sched_tick()

   - Move the timer start tracepoint to a place where it actually makes
     sense

   - Add documentation to timerqueue functions as they caused confusion
     several times now"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timerqueue: Document return values of timerqueue_add/del()
  timers: Invoke timer_start_debug() where it makes sense
  nohz: Prevent a timer interrupt storm in tick_nohz_stop_sched_tick()
  timers: Reinitialize per cpu bases on hotplug
  timers: Use deferrable base independent of base::nohz_active

2 files changed, 4 insertions, 2 deletions

diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h
index 201ab7267986..1a32e558eb11 100644
--- a/include/linux/cpuhotplug.h
+++ b/include/linux/cpuhotplug.h
@@ -86,7 +86,7 @@ enum cpuhp_state {
         CPUHP_MM_ZSWP_POOL_PREPARE,
         CPUHP_KVM_PPC_BOOK3S_PREPARE,
         CPUHP_ZCOMP_PREPARE,
-        CPUHP_TIMERS_DEAD,
+        CPUHP_TIMERS_PREPARE,
         CPUHP_MIPS_SOC_PREPARE,
         CPUHP_BP_PREPARE_DYN,
         CPUHP_BP_PREPARE_DYN_END                = CPUHP_BP_PREPARE_DYN + 20,
diff --git a/include/linux/timer.h b/include/linux/timer.h
index 04af640ea95b..2448f9cc48a3 100644
--- a/include/linux/timer.h
+++ b/include/linux/timer.h
@@ -207,9 +207,11 @@ unsigned long round_jiffies_up(unsigned long j);
 unsigned long round_jiffies_up_relative(unsigned long j);
 
 #ifdef CONFIG_HOTPLUG_CPU
+int timers_prepare_cpu(unsigned int cpu);
 int timers_dead_cpu(unsigned int cpu);
 #else
-#define timers_dead_cpu NULL
+#define timers_prepare_cpu      NULL
+#define timers_dead_cpu         NULL
 #endif
 
 #endif