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

Pull irq core changes from Ingo Molnar:
 "The biggest changes are the IRQ-work and printk changes from Frederic
  Weisbecker, which prepare the code for 'full dynticks' (the ability to
  stop or slow down the periodic tick arbitrarily, not just in idle time
  as today):

   - 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.

   - Cleanups and fixes."

* 'irq-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  genirq: Export enable/disable_percpu_irq()
  arch Kconfig: Remove references to IRQ_PER_CPU
  irq_work: Remove return value from the irq_work_queue() function
  genirq: Avoid deadlock in spurious handling
  printk: Wake up klogd using irq_work
  irq_work: Make self-IPIs optable
  irq_work: Warn if there's still work on cpu_down
  irq_work: Flush work on CPU_DYING
  irq_work: Don't stop the tick with pending works
  nohz: Add API to check tick state
  irq_work: Remove CONFIG_HAVE_IRQ_WORK
  irq_work: Fix racy check on work pending flag
  irq_work: Fix racy IRQ_WORK_BUSY flag setting

1 files changed, 20 insertions, 16 deletions

diff --git a/kernel/printk.c b/kernel/printk.c
index 267ce780abe8..f24633afa46a 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -42,6 +42,7 @@
 #include <linux/notifier.h>
 #include <linux/rculist.h>
 #include <linux/poll.h>
+#include <linux/irq_work.h>
 
 #include <asm/uaccess.h>
 
@@ -1959,30 +1960,32 @@ int is_console_locked(void)
 static DEFINE_PER_CPU(int, printk_pending);
 static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
 
-void printk_tick(void)
+static void wake_up_klogd_work_func(struct irq_work *irq_work)
 {
-	if (__this_cpu_read(printk_pending)) {
-		int pending = __this_cpu_xchg(printk_pending, 0);
-		if (pending & PRINTK_PENDING_SCHED) {
-			char *buf = __get_cpu_var(printk_sched_buf);
-			printk(KERN_WARNING "[sched_delayed] %s", buf);
-		}
-		if (pending & PRINTK_PENDING_WAKEUP)
-			wake_up_interruptible(&log_wait);
+	int pending = __this_cpu_xchg(printk_pending, 0);
+
+	if (pending & PRINTK_PENDING_SCHED) {
+		char *buf = __get_cpu_var(printk_sched_buf);
+		printk(KERN_WARNING "[sched_delayed] %s", buf);
 	}
-}
 
-int printk_needs_cpu(int cpu)
-{
-	if (cpu_is_offline(cpu))
-		printk_tick();
-	return __this_cpu_read(printk_pending);
+	if (pending & PRINTK_PENDING_WAKEUP)
+		wake_up_interruptible(&log_wait);
 }
 
+static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
+	.func = wake_up_klogd_work_func,
+	.flags = IRQ_WORK_LAZY,
+};
+
 void wake_up_klogd(void)
 {
-	if (waitqueue_active(&log_wait))
+	preempt_disable();
+	if (waitqueue_active(&log_wait)) {
 		this_cpu_or(printk_pending, PRINTK_PENDING_WAKEUP);
+		irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
+	}
+	preempt_enable();
 }
 
 static void console_cont_flush(char *text, size_t size)
@@ -2462,6 +2465,7 @@ int printk_sched(const char *fmt, ...)
 	va_end(args);
 
 	__this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
+	irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
 	local_irq_restore(flags);
 
 	return r;