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 <[email protected]>
Signed-off-by: John Ogness <[email protected]>
Reviewed-by: Petr Mladek <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Petr Mladek <[email protected]>

2 files changed, 15 insertions, 0 deletions

diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index 398ecb40d279..dc8bc0890fd2 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -53,6 +53,9 @@ int vprintk_store(int facility, int level,
 __printf(1, 0) int vprintk_default(const char *fmt, va_list args);
 __printf(1, 0) int vprintk_deferred(const char *fmt, va_list args);
 
+void __printk_safe_enter(void);
+void __printk_safe_exit(void);
+
 bool printk_percpu_data_ready(void);
 
 #define printk_safe_enter_irqsave(flags)	\
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index 6d10927a07d8..4421ccac3113 100644
--- 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();
+	__printk_safe_enter();
+}
+
+void __printk_deferred_exit(void)
+{
+	cant_migrate();
+	__printk_safe_exit();
+}
+
 asmlinkage int vprintk(const char *fmt, va_list args)
 {
 #ifdef CONFIG_KGDB_KDB