From ea285b2f6e2c4bc71560f78c95415a8fc6954085 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 22 Sep 2023 14:58:18 +0000
Subject: [PATCH 125/204] printk: Check printk_deferred_enter()/_exit() usage

Add validation that printk_deferred_enter()/_exit() are called in
non-migration contexts.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 include/linux/printk.h      |    7 +++++--
 kernel/printk/printk_safe.c |   12 ++++++++++++
 2 files changed, 17 insertions(+), 2 deletions(-)

Index: linux-6.6.58-rt45/include/linux/printk.h
===================================================================
@ linux-6.6.58-rt45/include/linux/printk.h:162 @ __printf(1, 2) __cold int _printk_deferr
 
 extern void __printk_safe_enter(void);
 extern void __printk_safe_exit(void);
+extern void __printk_deferred_enter(void);
+extern void __printk_deferred_exit(void);
+
 /*
  * The printk_deferred_enter/exit macros are available only as a hack for
  * some code paths that need to defer all printk console printing. Interrupts
  * must be disabled for the deferred duration.
  */
-#define printk_deferred_enter __printk_safe_enter
-#define printk_deferred_exit __printk_safe_exit
+#define printk_deferred_enter() __printk_deferred_enter()
+#define printk_deferred_exit() __printk_deferred_exit()
 
 /*
  * Please don't use printk_ratelimit(), because it shares ratelimiting state
Index: linux-6.6.58-rt45/kernel/printk/printk_safe.c
===================================================================
--- linux-6.6.58-rt45.orig/kernel/printk/printk_safe.c
+++ linux-6.6.58-rt45/kernel/printk/printk_safe.c
@ linux-6.6.58-rt45/include/linux/printk.h:29 @ void __printk_safe_exit(void)
 	this_cpu_dec(printk_context);
 }
 
+void __printk_deferred_enter(void)
+{
+	cant_migrate();
+	this_cpu_inc(printk_context);
+}
+
+void __printk_deferred_exit(void)
+{
+	cant_migrate();
+	this_cpu_dec(printk_context);
+}
+
 asmlinkage int vprintk(const char *fmt, va_list args)
 {
 #ifdef CONFIG_KGDB_KDB