5 files changed, 22 insertions, 21 deletions

diff --git a/include/linux/printk.h b/include/linux/printk.h
index 9afc01e5a0a6..86c4b6294713 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -98,9 +98,6 @@ int no_printk(const char *fmt, ...)
 extern asmlinkage __printf(1, 2)
 void early_printk(const char *fmt, ...);
 
-extern int printk_needs_cpu(int cpu);
-extern void printk_tick(void);
-
 #ifdef CONFIG_PRINTK
 asmlinkage __printf(5, 0)
 int vprintk_emit(int facility, int level,
diff --git a/init/Kconfig b/init/Kconfig
index cdc152c75727..c575566be47d 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1196,6 +1196,7 @@ config HOTPLUG
 config PRINTK
         default y
         bool "Enable support for printk" if EXPERT
+        select IRQ_WORK
         help
           This option enables normal printk support. Removing it
           eliminates most of the message strings from the kernel image
diff --git a/kernel/printk.c b/kernel/printk.c
index 2d607f4d1797..c9104feba5ec 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>
 
@@ -1955,30 +1956,32 @@ 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)
@@ -2458,6 +2461,7 @@ 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;
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index f249e8c3e58e..822d7572bf2d 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -289,7 +289,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
                 time_delta = timekeeping_max_deferment();
         } while (read_seqretry(&xtime_lock, seq));
 
-        if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || printk_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;
diff --git a/kernel/timer.c b/kernel/timer.c
index 367d00858482..ff3b5165737b 100644
--- a/kernel/timer.c
+++ b/kernel/timer.c
@@ -1351,7 +1351,6 @@ void update_process_times(int user_tick)
         account_process_tick(p, user_tick);
         run_local_timers();
         rcu_check_callbacks(cpu, user_tick);
-        printk_tick();
 #ifdef CONFIG_IRQ_WORK
         if (in_irq())
                 irq_work_run();