In commit b1fca27d384e ("kernel debug: support resetting WARN*_ONCE")
we got the opportunity to reset state on the one shot messages,
without having to reboot.
However printk_once (printk_deferred_once) live in a different file
and didn't get the same kind of update/conversion, so they remain
unconditionally one shot, until the system is rebooted.
For example, we currently have:
sched/rt.c: printk_deferred_once("sched: RT throttling activated\n");
..which could reasonably be tripped as someone is testing and tuning
a new system/workload and their task placements. For consistency, and
to avoid reboots in the same vein as the original commit, we make these
two instances of _once the same as the WARN*_ONCE instances are.
Cc: Andi Kleen <[email protected]>
Cc: Petr Mladek <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Andrew Morton <[email protected]>
Signed-off-by: Paul Gortmaker <[email protected]>
---
Documentation/clearing-warn-once.txt | 2 +-
include/linux/printk.h | 4 ++--
2 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/Documentation/clearing-warn-once.txt b/Documentation/clearing-warn-once.txt
index 5b1f5d547be1..c68598b31428 100644
--- a/Documentation/clearing-warn-once.txt
+++ b/Documentation/clearing-warn-once.txt
@@ -1,5 +1,5 @@
-WARN_ONCE / WARN_ON_ONCE only print a warning once.
+WARN_ONCE / WARN_ON_ONCE / printk_once only emit a message once.
echo 1 > /sys/kernel/debug/clear_warn_once
diff --git a/include/linux/printk.h b/include/linux/printk.h
index d7c77ed1a4cb..84ea4d094af3 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -347,7 +347,7 @@ extern int kptr_restrict;
#ifdef CONFIG_PRINTK
#define printk_once(fmt, ...) \
({ \
- static bool __print_once __read_mostly; \
+ static bool __section(.data.once) __print_once; \
bool __ret_print_once = !__print_once; \
\
if (!__print_once) { \
@@ -358,7 +358,7 @@ extern int kptr_restrict;
})
#define printk_deferred_once(fmt, ...) \
({ \
- static bool __print_once __read_mostly; \
+ static bool __section(.data.once) __print_once; \
bool __ret_print_once = !__print_once; \
\
if (!__print_once) { \
--
2.7.4
On (04/12/19 22:11), Paul Gortmaker wrote:
> In commit b1fca27d384e ("kernel debug: support resetting WARN*_ONCE")
> we got the opportunity to reset state on the one shot messages,
> without having to reboot.
Didn't know that.
> However printk_once (printk_deferred_once) live in a different file
> and didn't get the same kind of update/conversion, so they remain
> unconditionally one shot, until the system is rebooted.
>
> For example, we currently have:
>
> sched/rt.c: printk_deferred_once("sched: RT throttling activated\n");
>
> ..which could reasonably be tripped as someone is testing and tuning
> a new system/workload and their task placements. For consistency, and
> to avoid reboots in the same vein as the original commit, we make these
> two instances of _once the same as the WARN*_ONCE instances are.
Looks OK to me.
Reviewed-by: Sergey Senozhatsky <[email protected]>
-ss
On Mon 2019-04-15 11:32:16, Sergey Senozhatsky wrote:
> On (04/12/19 22:11), Paul Gortmaker wrote:
> > In commit b1fca27d384e ("kernel debug: support resetting WARN*_ONCE")
> > we got the opportunity to reset state on the one shot messages,
> > without having to reboot.
>
> Didn't know that.
>
> > However printk_once (printk_deferred_once) live in a different file
> > and didn't get the same kind of update/conversion, so they remain
> > unconditionally one shot, until the system is rebooted.
> >
> > For example, we currently have:
> >
> > sched/rt.c: printk_deferred_once("sched: RT throttling activated\n");
> >
> > ..which could reasonably be tripped as someone is testing and tuning
> > a new system/workload and their task placements. For consistency, and
> > to avoid reboots in the same vein as the original commit, we make these
> > two instances of _once the same as the WARN*_ONCE instances are.
>
> Looks OK to me.
>
> Reviewed-by: Sergey Senozhatsky <[email protected]>
The patch has been commited into printk.git, branch for-5.2.
Best Regards,
Petr