lkb_defer_softirq.patch

From 8c0d436eee113426bdfdfc028b057133e5162e90 Mon Sep 17 00:00:00 2001
From: Savio Machado <sav@loophole.cc>
Date: Tue, 25 Sep 2018 02:20:00 -0300
Subject: [PATCH] kernel/softirq.c: add new dummie softirq
To: sav@loophole.cc

will print a message whenever a module is successfully loaded.
---
 include/linux/interrupt.h | 1 +
 kernel/module.c           | 2 ++
 kernel/softirq.c          | 7 +++++++
 3 files changed, 10 insertions(+)

diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index eeceac3376fc..4a6ef4cb03e2 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -468,6 +468,7 @@ enum
 	NET_RX_SOFTIRQ,
 	BLOCK_SOFTIRQ,
 	IRQ_POLL_SOFTIRQ,
+	LKB_SOFTIRQ,
 	TASKLET_SOFTIRQ,
 	SCHED_SOFTIRQ,
 	HRTIMER_SOFTIRQ, /* Unused, but kept as tools rely on the
diff --git a/kernel/module.c b/kernel/module.c
index 6746c85511fe..bd27526156e8 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -40,6 +40,7 @@
 #include <linux/moduleparam.h>
 #include <linux/errno.h>
 #include <linux/err.h>
+#include <linux/interrupt.h>
 #include <linux/vermagic.h>
 #include <linux/notifier.h>
 #include <linux/sched.h>
@@ -3509,6 +3510,7 @@ static noinline int do_init_module(struct module *mod)
 	call_rcu_sched(&freeinit->rcu, do_free_init);
 	mutex_unlock(&module_mutex);
 	wake_up_all(&module_wq);
+	raise_softirq(LKB_SOFTIRQ);
 
 	return 0;
 
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 6f584861d329..a792a091cad6 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -545,6 +545,12 @@ static __latent_entropy void tasklet_hi_action(struct softirq_action *a)
 	tasklet_action_common(a, this_cpu_ptr(&tasklet_hi_vec), HI_SOFTIRQ);
 }
 
+static __latent_entropy void lkb_softirq_action(struct softirq_action *a)
+{
+	/* runs with interrupt enabled, can't sleep */
+	printk(KERN_DEBUG "%s: module loaded\n", __FUNCTION__);
+}
+
 void tasklet_init(struct tasklet_struct *t,
 		  void (*func)(unsigned long), unsigned long data)
 {
@@ -635,6 +641,7 @@ void __init softirq_init(void)
 
 	open_softirq(TASKLET_SOFTIRQ, tasklet_action);
 	open_softirq(HI_SOFTIRQ, tasklet_hi_action);
+	open_softirq(LKB_SOFTIRQ, lkb_softirq_action);
 }
 
 static int ksoftirqd_should_run(unsigned int cpu)
-- 
2.17.1