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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 22 Sep 2023 14:58:18 +0000
Subject: [PATCH 18/50] printk: Check printk_deferred_enter()/_exit() usage
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.7/older/patches-6.7-rt6.tar.xz
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(-)
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -159,13 +159,16 @@ int _printk(const char *fmt, ...);
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
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -26,6 +26,18 @@ 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
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