[RFT 3/4] chaoskey: make read() obey O_NONBLOCK

[Oliver Neukum <oneukum@xxxxxxxx>]

This skips waiting for a read if O_NONBLOCK is set.

Signed-off-by: Oliver Neukum <oneukum@xxxxxxxx>
---
 drivers/usb/misc/chaoskey.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/misc/chaoskey.c b/drivers/usb/misc/chaoskey.c
index d47c2cc65269..0d80cba162a4 100644
--- a/drivers/usb/misc/chaoskey.c
+++ b/drivers/usb/misc/chaoskey.c
@@ -467,10 +467,14 @@ static ssize_t chaoskey_read(struct file *file,
 				mutex_unlock(&dev->lock);
 				goto bail;
 			}
-			result = chaoskey_wait_fill(dev);
-			if (result < 0) {
-				mutex_unlock(&dev->lock);
-				goto bail;
+			if (!(file->f_flags & O_NONBLOCK)) {
+				result = chaoskey_wait_fill(dev);
+				if (result < 0) {
+					mutex_unlock(&dev->lock);
+					goto bail;
+				}
+			} else {
+				result = -EAGAIN;
 			}
 		}
 
-- 
2.16.4