linux-kernel - [Update 2x][PATCH 7/7] PM / Domains: Automatically update overoptimistic latency information

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <201111191502.51686.rjw@sisk.pl>
Date:	Sat, 19 Nov 2011 15:02:51 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Linux PM list <linux-pm@...r.kernel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	"Linux-sh list" <linux-sh@...r.kernel.org>,
	Magnus Damm <magnus.damm@...il.com>,
	Guennadi Liakhovetski <g.liakhovetski@....de>,
	Kevin Hilman <khilman@...com>, jean.pihet@...oldbits.com
Subject: [Update 2x][PATCH 7/7] PM / Domains: Automatically update overoptimistic latency information

From: Rafael J. Wysocki <rjw@...k.pl>

Measure the time of execution of the .stop(), .start(), .save_state()
and .restore_state() PM domain device callbacks and if the result
is greater than the corresponding latency value stored in the
device's struct generic_pm_domain_data object, replace the inaccurate
value with the measured time.

Do analogously for the PM domains' .power_off() and .power_off()
callbacks.

Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
 drivers/base/power/domain.c |   43 +++++++++++++++++++++++++++++++++++++++----
 1 file changed, 39 insertions(+), 4 deletions(-)

Index: linux/drivers/base/power/domain.c
===================================================================
--- linux.orig/drivers/base/power/domain.c
+++ linux/drivers/base/power/domain.c
@@ -33,6 +33,20 @@
 	__ret;							\
 })
 
+#define GENPD_DEV_TIMED_CALLBACK(genpd, type, callback, dev, field, name)	\
+({										\
+	ktime_t __start = ktime_get();						\
+	type __retval = GENPD_DEV_CALLBACK(genpd, type, callback, dev);		\
+	s64 __elapsed = ktime_to_ns(ktime_sub(ktime_get(), __start));		\
+	struct generic_pm_domain_data *__gpd_data = dev_gpd_data(dev);		\
+	if (__elapsed > __gpd_data->td.field) {					\
+		__gpd_data->td.field = __elapsed;				\
+		dev_warn(dev, name " latency exceeded, new value %lld ns\n",	\
+			__elapsed);						\
+	}									\
+	__retval;								\
+})
+
 static LIST_HEAD(gpd_list);
 static DEFINE_MUTEX(gpd_list_lock);
 
@@ -48,22 +62,27 @@ struct generic_pm_domain *dev_to_genpd(s
 
 static int genpd_stop_dev(struct generic_pm_domain *genpd, struct device *dev)
 {
-	return GENPD_DEV_CALLBACK(genpd, int, stop, dev);
+	return GENPD_DEV_TIMED_CALLBACK(genpd, int, stop, dev,
+					stop_latency_ns, "stop");
 }
 
 static int genpd_start_dev(struct generic_pm_domain *genpd, struct device *dev)
 {
-	return GENPD_DEV_CALLBACK(genpd, int, start, dev);
+	return GENPD_DEV_TIMED_CALLBACK(genpd, int, start, dev,
+					start_latency_ns, "start");
 }
 
 static int genpd_save_dev(struct generic_pm_domain *genpd, struct device *dev)
 {
-	return GENPD_DEV_CALLBACK(genpd, int, save_state, dev);
+	return GENPD_DEV_TIMED_CALLBACK(genpd, int, save_state, dev,
+					save_state_latency_ns, "state save");
 }
 
 static int genpd_restore_dev(struct generic_pm_domain *genpd, struct device *dev)
 {
-	return GENPD_DEV_CALLBACK(genpd, int, restore_state, dev);
+	return GENPD_DEV_TIMED_CALLBACK(genpd, int, restore_state, dev,
+					restore_state_latency_ns,
+					"state restore");
 }
 
 static bool genpd_sd_counter_dec(struct generic_pm_domain *genpd)
@@ -182,9 +201,16 @@ int __pm_genpd_poweron(struct generic_pm
 	}
 
 	if (genpd->power_on) {
+		ktime_t time_start = ktime_get();
+		s64 elapsed_ns;
+
 		ret = genpd->power_on(genpd);
 		if (ret)
 			goto err;
+
+		elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
+		if (elapsed_ns > genpd->power_on_latency_ns)
+			genpd->power_on_latency_ns = elapsed_ns;
 	}
 
 	genpd_set_active(genpd);
@@ -377,11 +403,16 @@ static int pm_genpd_poweroff(struct gene
 	}
 
 	if (genpd->power_off) {
+		ktime_t time_start;
+		s64 elapsed_ns;
+
 		if (atomic_read(&genpd->sd_count) > 0) {
 			ret = -EBUSY;
 			goto out;
 		}
 
+		time_start = ktime_get();
+
 		/*
 		 * If sd_count > 0 at this point, one of the subdomains hasn't
 		 * managed to call pm_genpd_poweron() for the master yet after
@@ -395,6 +426,10 @@ static int pm_genpd_poweroff(struct gene
 			genpd_set_active(genpd);
 			goto out;
 		}
+
+		elapsed_ns = ktime_to_ns(ktime_sub(ktime_get(), time_start));
+		if (elapsed_ns > genpd->power_off_latency_ns)
+			genpd->power_off_latency_ns = elapsed_ns;
 	}
 
 	genpd->status = GPD_STATE_POWER_OFF;

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/