From: Jan Kara <j...@suse.cz>
Offload printing of scheduler deferred messages from IRQ context
to a schedulable printing kthread, when possible (the same way we
do it in vprintk_emit()). Otherwise, the CPU can spend unbounded
amount of time doing printing in console_unlock() from IRQ.
Signed-off-by: Jan Kara <j...@suse.cz>
Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com>
Reviewed-by: Petr Mladek <pmla...@suse.com>
---
kernel/printk/printk.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 2e50c48..c346763 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2815,9 +2815,16 @@ static void wake_up_klogd_work_func(struct irq_work
*irq_work)
int pending = __this_cpu_xchg(printk_pending, 0);
if (pending & PRINTK_PENDING_OUTPUT) {
- /* If trylock fails, someone else is doing the printing */
- if (console_trylock())
- console_unlock();
+ if (printk_kthread) {
+ wake_up_process(printk_kthread);
+ } else {
+ /*
+ * If trylock fails, someone else is doing
+ * the printing
+ */
+ if (console_trylock())
+ console_unlock();
+ }
}
if (pending & PRINTK_PENDING_WAKEUP)
--
2.8.0
