diff options
Diffstat (limited to 'net/tap-linux.c')
| -rw-r--r-- | net/tap-linux.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/net/tap-linux.c b/net/tap-linux.c index c6521bec34..3eaedc40ad 100644 --- a/net/tap-linux.c +++ b/net/tap-linux.c @@ -39,6 +39,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required { struct ifreq ifr; int fd, ret; + int len = sizeof(struct virtio_net_hdr); TFR(fd = open(PATH_NET_TUN, O_RDWR)); if (fd < 0) { @@ -65,6 +66,13 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required close(fd); return -1; } + /* + * Make sure vnet header size has the default value: for a persistent + * tap it might have been modified e.g. by another instance of qemu. + * Ignore errors since old kernels do not support this ioctl: in this + * case the header size implicitly has the correct value. + */ + ioctl(fd, TUNSETVNETHDRSZ, &len); } if (ifname[0] != '\0') |