swsusp: Fix userland interface
Fix oops caused by 'cat /dev/snapshot', reported by Arkadiusz Miskiewicz,
and make it impossible to thaw tasks with the help of the swsusp userland
interface while there is a snapshot image ready to save.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/power/user.c b/kernel/power/user.c
index 24d7d78..d65305b 100644
--- a/kernel/power/user.c
+++ b/kernel/power/user.c
@@ -99,6 +99,8 @@
ssize_t res;
data = filp->private_data;
+ if (!data->ready)
+ return -ENODATA;
res = snapshot_read_next(&data->handle, count);
if (res > 0) {
if (copy_to_user(buf, data_of(data->handle), res))
@@ -245,7 +247,7 @@
break;
case SNAPSHOT_UNFREEZE:
- if (!data->frozen)
+ if (!data->frozen || data->ready)
break;
mutex_lock(&pm_mutex);
thaw_processes();