PM / Hibernate: Thaw processes in SNAPSHOT_CREATE_IMAGE ioctl test path

commit 97819a26 upstream.

Commit 2aede851 (PM / Hibernate: Freeze
kernel threads after preallocating memory) moved the freezing of kernel
threads to hibernation_snapshot() function.

So now, if the call to hibernation_snapshot() returns early due to a
successful hibernation test, the caller has to thaw processes to ensure
that the system gets back to its original state.

But in SNAPSHOT_CREATE_IMAGE hibernation ioctl, the caller does not thaw
processes in case hibernation_snapshot() returned due to a successful
freezer test. Fix this issue. But note we still send the value of 'in_suspend'
(which is now 0) to userspace, because we are not in an error path per-se,
and moreover, the value of in_suspend correctly depicts the situation here.
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

kernel/power/hibernate.c

@@ -55,7 +55,7 @@ enum {
 
 static int hibernation_mode = HIBERNATION_SHUTDOWN;
 
-static bool freezer_test_done;
+bool freezer_test_done;
 
 static const struct platform_hibernation_ops *hibernation_ops;
 

kernel/power/power.h

@@ -50,6 +50,8 @@ static inline char *check_image_kernel(struct swsusp_info *info)
 #define SPARE_PAGES	((1024 * 1024) >> PAGE_SHIFT)
 
 /* kernel/power/hibernate.c */
+extern bool freezer_test_done;
+
 extern int hibernation_snapshot(int platform_mode);
 extern int hibernation_restore(int platform_mode);
 extern int hibernation_platform_enter(void);

kernel/power/user.c

@@ -283,10 +283,15 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd,
 		}
 		pm_restore_gfp_mask();
 		error = hibernation_snapshot(data->platform_support);
-		if (!error)
+		if (!error) {
 			error = put_user(in_suspend, (int __user *)arg);
-		if (!error)
-			data->ready = 1;
+			if (!error && !freezer_test_done)
+				data->ready = 1;
+			if (freezer_test_done) {
+				freezer_test_done = false;
+				thaw_processes();
+			}
+		}
 		break;
 
 	case SNAPSHOT_ATOMIC_RESTORE: