printk: Wake up klogd using irq_work

klogd is woken up asynchronously from the tick in order
to do it safely.

However if printk is called when the tick is stopped, the reader
won't be woken up until the next interrupt, which might not fire
for a while. As a result, the user may miss some message.

To fix this, lets implement the printk tick using a lazy irq work.
This subsystem takes care of the timer tick state and can
fix up accordingly.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>

1 files changed, 1 insertions, 0 deletions

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