On 2018-07-26 23:38:05 [+0530], Pintu Kumar wrote:
> > > Is there a way we can fix this issue on non-rt kernel?
> > I would guess that a wakeup to klogd would fix it.
> >
> Sorry, can you elaborate more about "wakeup to klogd".
> I wanted to try it and check.
Something like this should do the work.
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 179ad787a08c..411f9ed5f051 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -1927,6 +1927,8 @@ static size_t log_output(int facility, int level, enum log_flags lflags, const c
return log_store(facility, level, lflags, 0, dict, dictlen, text, text_len);
}
+static void printk_flush_pending_output(void);
+
asmlinkage int vprintk_emit(int facility, int level,
const char *dict, size_t dictlen,
const char *fmt, va_list args)
@@ -2026,6 +2028,9 @@ asmlinkage int vprintk_emit(int facility, int level,
*/
if (may_trylock && console_trylock_spinning())
console_unlock();
+ else if (!may_trylock)
+ printk_flush_pending_output();
+
migrate_enable();
}
@@ -2987,6 +2992,13 @@ static DEFINE_PER_CPU(struct irq_work, wake_up_klogd_work) = {
.flags = IRQ_WORK_LAZY,
};
+static void printk_flush_pending_output(void)
+{
+ /* preemption or interrupts need to be disabled */
+ __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
+ irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
+}
+
void wake_up_klogd(void)
{
preempt_disable();
Sebastian
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