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Diffstat (limited to 'net/tap-linux.c')
-rw-r--r--net/tap-linux.c8
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')