Merge branch 'nohz/printk-v8' into irq/core

Conflicts:
	kernel/irq_work.c

Add support for printk in full dynticks CPU.

* Don't stop tick with irq works pending. This
fix is generally useful and concerns archs that
can't raise self IPIs.

* Flush irq works before CPU offlining.

* Introduce "lazy" irq works that can wait for the
next tick to be executed, unless it's stopped.

* Implement klogd wake up using irq work. This
removes the ad-hoc printk_tick()/printk_needs_cpu()
hooks and make it working even in dynticks mode.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>

diff --cc include/linux/irq_work.h
Simple merge

diff --cc include/linux/tick.h
Simple merge

diff --cc init/Kconfig
Simple merge

diff --cc kernel/irq_work.c
index c9d7478e4889937e053e283ede32a0ad321764e0,7f3a59bc8e3d97660a8e75fdf6847fd4124f96c6..55fcce6065cf6bc3213829fd8188cae90b61b778
--- 1/kernel/irq_work.c
--- 2/kernel/irq_work.c
+++ b/kernel/irq_work.c
@@@ -63,37 -56,64 +56,53 @@@ void __weak arch_irq_work_raise(void
  }
  
  /*
 - * Queue the entry and raise the IPI if needed.
 + * Enqueue the irq_work @entry unless it's already pending
 + * somewhere.
 + *
 + * Can be re-enqueued while the callback is still in progress.
   */
 -static void __irq_work_queue(struct irq_work *work)
 +void irq_work_queue(struct irq_work *work)
  {
-       bool empty;
- 
 +      /* Only queue if not already pending */
 +      if (!irq_work_claim(work))
 +              return;
 +
 +      /* Queue the entry and raise the IPI if needed. */
        preempt_disable();
  
-       empty = llist_add(&work->llnode, &__get_cpu_var(irq_work_list));
-       /* The list was empty, raise self-interrupt to start processing. */
-       if (empty)
-               arch_irq_work_raise();
+       llist_add(&work->llnode, &__get_cpu_var(irq_work_list));
+ 
+       /*
+        * If the work is not "lazy" or the tick is stopped, raise the irq
+        * work interrupt (if supported by the arch), otherwise, just wait
+        * for the next tick.
+        */
+       if (!(work->flags & IRQ_WORK_LAZY) || tick_nohz_tick_stopped()) {
+               if (!this_cpu_cmpxchg(irq_work_raised, 0, 1))
+                       arch_irq_work_raise();
+       }
  
        preempt_enable();
  }
 -
 -/*
 - * Enqueue the irq_work @entry, returns true on success, failure when the
 - * @entry was already enqueued by someone else.
 - *
 - * Can be re-enqueued while the callback is still in progress.
 - */
 -bool irq_work_queue(struct irq_work *work)
 -{
 -      if (!irq_work_claim(work)) {
 -              /*
 -               * Already enqueued, can't do!
 -               */
 -              return false;
 -      }
 -
 -      __irq_work_queue(work);
 -      return true;
 -}
  EXPORT_SYMBOL_GPL(irq_work_queue);
  
- /*
-  * Run the irq_work entries on this cpu. Requires to be ran from hardirq
-  * context with local IRQs disabled.
-  */
- void irq_work_run(void)
+ bool irq_work_needs_cpu(void)
+ {
+       struct llist_head *this_list;
+ 
+       this_list = &__get_cpu_var(irq_work_list);
+       if (llist_empty(this_list))
+               return false;
+ 
+       /* All work should have been flushed before going offline */
+       WARN_ON_ONCE(cpu_is_offline(smp_processor_id()));
+ 
+       return true;
+ }
+ 
+ static void __irq_work_run(void)
  {
+       unsigned long flags;
        struct irq_work *work;
        struct llist_head *this_list;
        struct llist_node *llnode;

diff --cc kernel/printk.c
Simple merge

diff --cc kernel/time/tick-sched.c
index d58e552d9fd154b39fffaa012a6028838b9955fd,822d7572bf2dcb35163ff6e8aacc5bd440fd6d2b..fb8e5e469d1cdf82c559f6fe15835d3b70410aef
--- 1/kernel/time/tick-sched.c
--- 2/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@@ -28,10 -29,10 +29,10 @@@
  /*
   * Per cpu nohz control structure
   */
- static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched);
+ DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched);
  
  /*
 - * The time, when the last jiffy update happened. Protected by xtime_lock.
 + * The time, when the last jiffy update happened. Protected by jiffies_lock.
   */
  static ktime_t last_jiffies_update;
  
@@@ -329,10 -287,10 +330,10 @@@ static ktime_t tick_nohz_stop_sched_tic
                last_update = last_jiffies_update;
                last_jiffies = jiffies;
                time_delta = timekeeping_max_deferment();
 -      } while (read_seqretry(&xtime_lock, seq));
 +      } while (read_seqretry(&jiffies_lock, seq));
  
-       if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || printk_needs_cpu(cpu) ||
-           arch_needs_cpu(cpu)) {
+       if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) ||
+           arch_needs_cpu(cpu) || irq_work_needs_cpu()) {
                next_jiffies = last_jiffies + 1;
                delta_jiffies = 1;
        } else {