From: Sebastian Andrzej Siewior <[email protected]>
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]>
---
include/linux/printk.h | 7 +++++--
kernel/printk/printk_safe.c | 12 ++++++++++++
2 files changed, 17 insertions(+), 2 deletions(-)
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 955e31860095..8d5c5588eec9 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -159,13 +159,16 @@ __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/printk_safe.c b/kernel/printk/printk_safe.c
index 6d10927a07d8..8d9408d653de 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();
+ 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
--
2.39.2
On Sun 2024-02-18 20:03:07, John Ogness wrote:
> From: Sebastian Andrzej Siewior <[email protected]>
>
> Add validation that printk_deferred_enter()/_exit() are called in
> non-migration contexts.
>
> --- a/include/linux/printk.h
> +++ b/include/linux/printk.h
> @@ -159,13 +159,16 @@ __printf(1, 2) __cold int _printk_deferred(const char *fmt, ...);
>
> extern void __printk_safe_enter(void);
> extern void __printk_safe_exit(void);
It seems that these two does not longer need to stay in
the global linux/printk.h. The declaration can be
moved to kernel/printk/internal.h (with 'extern' removed).
> +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/printk_safe.c b/kernel/printk/printk_safe.c
> index 6d10927a07d8..8d9408d653de 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();
> + this_cpu_inc(printk_context);
I would prefer to call __printk_safe_enter() here to make
it clear that they update printk_context the same way
and have the same effect.
Let's make compiler to do the inlining.
> +}
> +
> +void __printk_deferred_exit(void)
> +{
> + cant_migrate();
> + this_cpu_dec(printk_context);
ditto
> +}
> +
> asmlinkage int vprintk(const char *fmt, va_list args)
> {
> #ifdef CONFIG_KGDB_KDB
With the two changes:
Reviewed-by: Petr Mladek <[email protected]>
Best Regards,
Petr