From: Sebastian Andrzej Siewior 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 Signed-off-by: John Ogness Signed-off-by: Sebastian Andrzej Siewior --- 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