[SLOF] [PATCH v2 1/2] virtio-serial: Make read and write methods report failure

[Jordan Niethe]

From: Kautuk Consul <kconsul at linux.vnet.ibm.com>

The read and write methods return successfully even if the virtio device
is closed (virtiodev is 0) and it is not able to send or receive any
characters.

Make the read and write methods return 0 to indicate they did not
succeed in this case.

This also fixes an invalid stack access in the read method.

Fixes: 8174acd ("virtio-serial: Close device completely")
Signed-off-by: Kautuk Consul <kconsul at linux.vnet.ibm.com>
Signed-off-by: Jordan Niethe <jniethe5 at gmail.com>
---
v2:
   - Rework commit message slightly
---
 board-qemu/slof/virtio-serial.fs | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/board-qemu/slof/virtio-serial.fs b/board-qemu/slof/virtio-serial.fs
index 82868e2..41e2e04 100644
--- a/board-qemu/slof/virtio-serial.fs
+++ b/board-qemu/slof/virtio-serial.fs
@@ -67,7 +67,7 @@ virtiodev virtio-serial-init drop
 ;
 
 : write ( addr len -- actual )
-    virtiodev 0= IF nip EXIT THEN
+    virtiodev 0= IF 2drop 0 EXIT THEN
     tuck
     0 ?DO
         dup c@ virtiodev SWAP virtio-serial-putchar
@@ -78,7 +78,7 @@ virtiodev virtio-serial-init drop
 
 : read ( addr len -- actual )
     0= IF drop 0 EXIT THEN
-    virtiodev 0= IF nip EXIT THEN
+    virtiodev 0= IF drop 0 EXIT THEN
     virtiodev virtio-serial-haschar 0= IF 0 swap c! -2 EXIT THEN
     virtiodev virtio-serial-getchar swap c! 1
 ;
-- 
2.39.3