1 files changed, 11 insertions, 1 deletions

diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
index a667637b54e3..f45a8ae5f828 100644
--- a/include/linux/eventfd.h
+++ b/include/linux/eventfd.h
@@ -13,10 +13,20 @@
 /* For O_CLOEXEC and O_NONBLOCK */
 #include <linux/fcntl.h>
 
-/* Flags for eventfd2.  */
+/*
+ * CAREFUL: Check include/asm-generic/fcntl.h when defining
+ * new flags, since they might collide with O_* ones. We want
+ * to re-use O_* flags that couldn't possibly have a meaning
+ * from eventfd, in order to leave a free define-space for
+ * shared O_* flags.
+ */
+#define EFD_SEMAPHORE (1 << 0)
 #define EFD_CLOEXEC O_CLOEXEC
 #define EFD_NONBLOCK O_NONBLOCK
 
+#define EFD_SHARED_FCNTL_FLAGS (O_CLOEXEC | O_NONBLOCK)
+#define EFD_FLAGS_SET (EFD_SHARED_FCNTL_FLAGS | EFD_SEMAPHORE)
+
 struct file *eventfd_fget(int fd);
 int eventfd_signal(struct file *file, int n);