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>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20240820063001.36405-5-john.ogness@linutronix.de
Signed-off-by: Petr Mladek <pmladek@suse.com>

diff --git a/include/linux/printk.h b/include/linux/printk.h
index b937cefcb31c9fcf078da94069b4cc198ce9c8f5..eee8e97da681e1e0e31878f36f62dd6cb2af7c6a 100644 (file)
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -161,15 +161,16 @@ int _printk(const char *fmt, ...);
  */
 __printf(1, 2) __cold int _printk_deferred(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

diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index 398ecb40d2796bbf5a5066830164d34cfceb8256..dc8bc0890fd2a938f64e17767ac1dcdeb212f9a1 100644 (file)
--- 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 6d10927a07d835043d1fe9f383053b9254691742..4421ccac311336f4e45b4149d5dbafa75ee7d70e 100644 (file)
--- 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