[PATCH 09/11] ALSA: usx2y: Don't call free_pages_exact() with NULL address

[Takashi Iwai]

Unlike some other functions, we can't pass NULL pointer to
free_pages_exact().  Add a proper NULL check for avoiding possible
Oops.

Signed-off-by: Takashi Iwai <tiwai at suse.de>
---
 sound/usb/usx2y/usb_stream.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/sound/usb/usx2y/usb_stream.c b/sound/usb/usx2y/usb_stream.c
index 820647331aba..9d0e44793896 100644
--- a/sound/usb/usx2y/usb_stream.c
+++ b/sound/usb/usx2y/usb_stream.c
@@ -143,8 +143,11 @@ void usb_stream_free(struct usb_stream_kernel *sk)
 	if (!s)
 		return;
 
-	free_pages_exact(sk->write_page, s->write_size);
-	sk->write_page = NULL;
+	if (sk->write_page) {
+		free_pages_exact(sk->write_page, s->write_size);
+		sk->write_page = NULL;
+	}
+
 	free_pages_exact(s, s->read_size);
 	sk->s = NULL;
 }
-- 
2.26.2