[PATCH] PM: Add pm_trace switch

Add the pm_trace attribute in /sys/power which has to be explicitly set to
one to really enable the "PM tracing" code compiled in when CONFIG_PM_TRACE
is set (which modifies the machine's CMOS clock in unpredictable ways).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 30 insertions, 0 deletions

diff --git a/kernel/power/main.c b/kernel/power/main.c
index 4d403323a7bb..873228c71dab 100644
--- a/kernel/power/main.c
+++ b/kernel/power/main.c
@@ -17,6 +17,7 @@
 #include <linux/pm.h>
 #include <linux/console.h>
 #include <linux/cpu.h>
+#include <linux/resume-trace.h>
 
 #include "power.h"
 
@@ -281,10 +282,39 @@ static ssize_t state_store(struct subsystem * subsys, const char * buf, size_t n
 
 power_attr(state);
 
+#ifdef CONFIG_PM_TRACE
+int pm_trace_enabled;
+
+static ssize_t pm_trace_show(struct subsystem * subsys, char * buf)
+{
+        return sprintf(buf, "%d\n", pm_trace_enabled);
+}
+
+static ssize_t
+pm_trace_store(struct subsystem * subsys, const char * buf, size_t n)
+{
+        int val;
+
+        if (sscanf(buf, "%d", &val) == 1) {
+                pm_trace_enabled = !!val;
+                return n;
+        }
+        return -EINVAL;
+}
+
+power_attr(pm_trace);
+
+static struct attribute * g[] = {
+        &state_attr.attr,
+        &pm_trace_attr.attr,
+        NULL,
+};
+#else
 static struct attribute * g[] = {
         &state_attr.attr,
         NULL,
 };
+#endif /* CONFIG_PM_TRACE */
 
 static struct attribute_group attr_group = {
         .attrs = g,