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printk: Check printk_deferred_enter()/_exit() usage

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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>
This commit is contained in:
Sebastian Andrzej Siewior 2024-08-20 08:35:30 +02:06 committed by Petr Mladek
parent d3ff380d47
commit 0e1d5731d3
3 changed files with 20 additions and 4 deletions
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9
include/linux/printk.h
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@ -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

3
kernel/printk/internal.h
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@ -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) \

12
kernel/printk/printk_safe.c
View File

@ -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