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authorDr. David Alan Gilbert <dgilbert@redhat.com>2018-05-04 10:53:46 +0100
committerMichael S. Tsirkin <mst@redhat.com>2018-05-23 17:02:02 +0300
commite3638151da2a314dda3ed862cf707b8b66aca4cb (patch)
tree6a39255d51b05aadf213c5a3c9ecc80801af185b
parent9952e807fd016c95f50372536f1ac65a601be6e4 (diff)
downloadqemu-arm-e3638151da2a314dda3ed862cf707b8b66aca4cb.tar.gz
libvhost-user: Send messages with no data
The response to a VHOST_USER_POSTCOPY_ADVISE contains a fd but doesn't actually contain any data. FIx vu_message_write so that it doesn't do a 0-byte write() call, since this was ending up with rc=0 that was confusing the error handling code. Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
-rw-r--r--contrib/libvhost-user/libvhost-user.c16
1 files changed, 9 insertions, 7 deletions
diff --git a/contrib/libvhost-user/libvhost-user.c b/contrib/libvhost-user/libvhost-user.c
index beeed0c43f..54e643d871 100644
--- a/contrib/libvhost-user/libvhost-user.c
+++ b/contrib/libvhost-user/libvhost-user.c
@@ -323,13 +323,15 @@ vu_message_write(VuDev *dev, int conn_fd, VhostUserMsg *vmsg)
rc = sendmsg(conn_fd, &msg, 0);
} while (rc < 0 && (errno == EINTR || errno == EAGAIN));
- do {
- if (vmsg->data) {
- rc = write(conn_fd, vmsg->data, vmsg->size);
- } else {
- rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->size);
- }
- } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
+ if (vmsg->size) {
+ do {
+ if (vmsg->data) {
+ rc = write(conn_fd, vmsg->data, vmsg->size);
+ } else {
+ rc = write(conn_fd, p + VHOST_USER_HDR_SIZE, vmsg->size);
+ }
+ } while (rc < 0 && (errno == EINTR || errno == EAGAIN));
+ }
if (rc <= 0) {
vu_panic(dev, "Error while writing: %s", strerror(errno));