epoll: Add a flag, EPOLLWAKEUP, to prevent suspend while epoll events are ready
When an epoll_event, that has the EPOLLWAKEUP flag set, is ready, a
wakeup_source will be active to prevent suspend. This can be used to
handle wakeup events from a driver that support poll, e.g. input, if
that driver wakes up the waitqueue passed to epoll before allowing
suspend.
Signed-off-by: Arve Hjønnevåg <arve@android.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
diff --git a/include/linux/capability.h b/include/linux/capability.h
index 12d52de..c398cff 100644
--- a/include/linux/capability.h
+++ b/include/linux/capability.h
@@ -360,8 +360,11 @@
#define CAP_WAKE_ALARM 35
+/* Allow preventing system suspends while epoll events are pending */
-#define CAP_LAST_CAP CAP_WAKE_ALARM
+#define CAP_EPOLLWAKEUP 36
+
+#define CAP_LAST_CAP CAP_EPOLLWAKEUP
#define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
diff --git a/include/linux/eventpoll.h b/include/linux/eventpoll.h
index 657ab55..6f8be32 100644
--- a/include/linux/eventpoll.h
+++ b/include/linux/eventpoll.h
@@ -26,6 +26,18 @@
#define EPOLL_CTL_DEL 2
#define EPOLL_CTL_MOD 3
+/*
+ * Request the handling of system wakeup events so as to prevent system suspends
+ * from happening while those events are being processed.
+ *
+ * Assuming neither EPOLLET nor EPOLLONESHOT is set, system suspends will not be
+ * re-allowed until epoll_wait is called again after consuming the wakeup
+ * event(s).
+ *
+ * Requires CAP_EPOLLWAKEUP
+ */
+#define EPOLLWAKEUP (1 << 29)
+
/* Set the One Shot behaviour for the target file descriptor */
#define EPOLLONESHOT (1 << 30)