[PATCH] PM: Fix sysfs interface

["Rafael J. Wysocki" <rjw@sisk.pl>]

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

The sysfs files /sys/power/disk and /sys/power/state do not work as documented,
since they allow the user to write only a few initial characters of the
input string to trigger the option (eg. 'echo pl > /sys/power/disk' activates
the platform mode of hibernation).  Fix it.

Special thanks to Peter Moulder <Peter.Moulder@infotech.monash.edu.au> for
pointing out the problem.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
 kernel/power/disk.c |    3 ++-
 kernel/power/main.c |    4 ++--
 2 files changed, 4 insertions(+), 3 deletions(-)

Index: linux-2.6.21/kernel/power/disk.c
===================================================================
--- linux-2.6.21.orig/kernel/power/disk.c
+++ linux-2.6.21/kernel/power/disk.c
@@ -416,7 +416,8 @@ static ssize_t disk_store(struct subsyst
 
 	mutex_lock(&pm_mutex);
 	for (i = HIBERNATION_FIRST; i <= HIBERNATION_MAX; i++) {
-		if (!strncmp(buf, hibernation_modes[i], len)) {
+		if (len == strlen(hibernation_modes[i])
+		    && !strncmp(buf, hibernation_modes[i], len)) {
 			mode = i;
 			break;
 		}
Index: linux-2.6.21/kernel/power/main.c
===================================================================
--- linux-2.6.21.orig/kernel/power/main.c
+++ linux-2.6.21/kernel/power/main.c
@@ -289,13 +289,13 @@ static ssize_t state_store(struct subsys
 	len = p ? p - buf : n;
 
 	/* First, check if we are requested to hibernate */
-	if (!strncmp(buf, "disk", len)) {
+	if (len == 4 && !strncmp(buf, "disk", len)) {
 		error = hibernate();
 		return error ? error : n;
 	}
 
 	for (s = &pm_states[state]; state < PM_SUSPEND_MAX; s++, state++) {
-		if (*s && !strncmp(buf, *s, len))
+		if (*s && len == strlen(s) && !strncmp(buf, *s, len))
 			break;
 	}
 	if (state < PM_SUSPEND_MAX && *s)