[PATCH] PM: fix dynamic debug within pm_pr_debug()

From: David Cohen
Date: Sun Mar 06 2022 - 00:56:59 EST


Currently, pm_pr_debug() and pm_deferred_pr_debug() use __pm_pr_debug()
to filter pm debug messages based on pm_debug_messages_on flag.
According to __pm_pr_debug() implementation, pm_deferred_pr_debug()
indirectly calls printk_deferred() within __pm_pr_debug() which doesn't
support dynamic debug, but pm_pr_debug() indirectly calls pr_debug()
which does support dynamic debug.

The problem is if we enable/disable dynamic debug inside __pm_pr_debug()
it will affect all pm_pr_debug() calls at once, so we can't individually
control them.

This patch changes __pm_pr_debug() implementation into macros to make
pr_debug() to be directly called by all pr_pm_debug() cases. As a direct
side effect all pr_pm_debug() can be individually controlled by dynamic
debug feature.

Signed-off-by: David Cohen <dacohen@xxxxx>
---
include/linux/suspend.h | 19 +++++++++++++++----
kernel/power/main.c | 29 -----------------------------
2 files changed, 15 insertions(+), 33 deletions(-)

diff --git a/include/linux/suspend.h b/include/linux/suspend.h
index 300273ff40cc..d727d3c867e3 100644
--- a/include/linux/suspend.h
+++ b/include/linux/suspend.h
@@ -542,22 +542,33 @@ static inline void unlock_system_sleep(void) {}
#ifdef CONFIG_PM_SLEEP_DEBUG
extern bool pm_print_times_enabled;
extern bool pm_debug_messages_on;
-extern __printf(2, 3) void __pm_pr_dbg(bool defer, const char *fmt, ...);
+#define __pm_pr_dbg(fmt, ...) \
+ do { \
+ if (pm_debug_messages_on) \
+ pr_debug("PM: " fmt, ##__VA_ARGS__); \
+ } while(0)
+#define __pm_deferred_pr_dbg(fmt, ...) \
+ do { \
+ if (pm_debug_messages_on) \
+ printk_deferred(KERN_DEBUG "PM: " fmt, ##__VA_ARGS__); \
+ } while(0)
#else
#define pm_print_times_enabled (false)
#define pm_debug_messages_on (false)

#include <linux/printk.h>

-#define __pm_pr_dbg(defer, fmt, ...) \
+#define __pm_pr_dbg(fmt, ...) \
+ no_printk(KERN_DEBUG fmt, ##__VA_ARGS__)
+#define __pm_deferred_pr_dbg(fmt, ...) \
no_printk(KERN_DEBUG fmt, ##__VA_ARGS__)
#endif

#define pm_pr_dbg(fmt, ...) \
- __pm_pr_dbg(false, fmt, ##__VA_ARGS__)
+ __pm_pr_dbg(fmt, ##__VA_ARGS__)

#define pm_deferred_pr_dbg(fmt, ...) \
- __pm_pr_dbg(true, fmt, ##__VA_ARGS__)
+ __pm_deferred_pr_dbg(fmt, ##__VA_ARGS__)

#ifdef CONFIG_PM_AUTOSLEEP

diff --git a/kernel/power/main.c b/kernel/power/main.c
index 7e646079fbeb..5242bf2ee469 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -545,35 +545,6 @@ static int __init pm_debug_messages_setup(char *str)
}
__setup("pm_debug_messages", pm_debug_messages_setup);

-/**
- * __pm_pr_dbg - Print a suspend debug message to the kernel log.
- * @defer: Whether or not to use printk_deferred() to print the message.
- * @fmt: Message format.
- *
- * The message will be emitted if enabled through the pm_debug_messages
- * sysfs attribute.
- */
-void __pm_pr_dbg(bool defer, const char *fmt, ...)
-{
- struct va_format vaf;
- va_list args;
-
- if (!pm_debug_messages_on)
- return;
-
- va_start(args, fmt);
-
- vaf.fmt = fmt;
- vaf.va = &args;
-
- if (defer)
- printk_deferred(KERN_DEBUG "PM: %pV", &vaf);
- else
- printk(KERN_DEBUG "PM: %pV", &vaf);
-
- va_end(args);
-}
-
#else /* !CONFIG_PM_SLEEP_DEBUG */
static inline void pm_print_times_init(void) {}
#endif /* CONFIG_PM_SLEEP_DEBUG */
--
2.35.1