[PATCH 3/3] PM / timekeeping: Print debug messages when requested

From: Rafael J. Wysocki
Date: Tue Jul 18 2017 - 20:51:20 EST


From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

The messages printed by tk_debug_account_sleep_time() are basically
useful for system sleep debugging, so print them only when the other
debug messages from the core suspend/hibernate code are enabled.

While at it, make it clear that the messages from
tk_debug_account_sleep_time() are about timekeeping suspend
duration, because in general timekeeping may be suspeded and
resumed for multiple times during one system suspend-resume cycle.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
include/linux/suspend.h | 10 ++++++++--
kernel/power/main.c | 10 +++++++---
kernel/time/timekeeping_debug.c | 5 +++--
3 files changed, 18 insertions(+), 7 deletions(-)

Index: linux-pm/include/linux/suspend.h
===================================================================
--- linux-pm.orig/include/linux/suspend.h
+++ linux-pm/include/linux/suspend.h
@@ -491,16 +491,22 @@ static inline void unlock_system_sleep(v

#ifdef CONFIG_PM_SLEEP_DEBUG
extern bool pm_print_times_enabled;
-extern __printf(1, 2) void pm_pr_dbg(const char *fmt, ...);
+extern __printf(2, 3) void __pm_pr_dbg(bool defer, const char *fmt, ...);
#else
#define pm_print_times_enabled (false)

#include <linux/printk.h>

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

+#define pm_pr_dbg(fmt, ...) \
+ __pm_pr_dbg(false, fmt, ##__VA_ARGS__)
+
+#define pm_deferred_pr_dbg(fmt, ...) \
+ __pm_pr_dbg(true, fmt, ##__VA_ARGS__)
+
#ifdef CONFIG_PM_AUTOSLEEP

/* kernel/power/autosleep.c */
Index: linux-pm/kernel/power/main.c
===================================================================
--- linux-pm.orig/kernel/power/main.c
+++ linux-pm/kernel/power/main.c
@@ -388,13 +388,14 @@ static ssize_t pm_debug_messages_store(s
power_attr(pm_debug_messages);

/**
- * pm_pr_dbg - Print a suspend debug message to the kernel log.
+ * __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(const char *fmt, ...)
+void __pm_pr_dbg(bool defer, const char *fmt, ...)
{
struct va_format vaf;
va_list args;
@@ -407,7 +408,10 @@ void pm_pr_dbg(const char *fmt, ...
vaf.fmt = fmt;
vaf.va = &args;

- printk(KERN_DEBUG "PM: %pV", &vaf);
+ if (defer)
+ printk_deferred(KERN_DEBUG "PM: %pV", &vaf);
+ else
+ printk(KERN_DEBUG "PM: %pV", &vaf);

va_end(args);
}
Index: linux-pm/kernel/time/timekeeping_debug.c
===================================================================
--- linux-pm.orig/kernel/time/timekeeping_debug.c
+++ linux-pm/kernel/time/timekeeping_debug.c
@@ -19,6 +19,7 @@
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/seq_file.h>
+#include <linux/suspend.h>
#include <linux/time.h>

#include "timekeeping_internal.h"
@@ -75,7 +76,7 @@ void tk_debug_account_sleep_time(struct
int bin = min(fls(t->tv_sec), NUM_BINS-1);

sleep_time_bin[bin]++;
- printk_deferred(KERN_INFO "Suspended for %lld.%03lu seconds\n",
- (s64)t->tv_sec, t->tv_nsec / NSEC_PER_MSEC);
+ pm_deferred_pr_dbg("Timekeeping suspended for %lld.%03lu seconds\n",
+ (s64)t->tv_sec, t->tv_nsec / NSEC_PER_MSEC);
}