| Message ID | 1259053593-15362-1-git-send-email-Pierre.Riteau@irisa.fr |
|---|---|
| State | New |
| Headers | show |
On Tue, 2009-11-24 at 10:06 +0100, Pierre Riteau wrote: > vnet_hdr is initialized at 1 by default. We need to reset it to 0 if > the kernel doesn't support IFF_VNET_HDR. > > Signed-off-by: Pierre Riteau <Pierre.Riteau@irisa.fr> Thanks Pierre, I see why this is needed now Acked-by: Mark McLoughlin <markmc@redhat.com> Cheers, Mark.
On 24 nov. 2009, at 11:28, Mark McLoughlin wrote: > On Tue, 2009-11-24 at 10:06 +0100, Pierre Riteau wrote: >> vnet_hdr is initialized at 1 by default. We need to reset it to 0 if >> the kernel doesn't support IFF_VNET_HDR. >> >> Signed-off-by: Pierre Riteau <Pierre.Riteau@irisa.fr> > > Thanks Pierre, I see why this is needed now > > Acked-by: Mark McLoughlin <markmc@redhat.com> > > Cheers, > Mark. Thanks for your rapid answer! BTW, every time I run qemu I see this error message: TUNSETOFFLOAD ioctl() failed: Invalid argument It is caused by the piece of code at the end of net/tap-linux.c: if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { offload &= ~TUN_F_UFO; if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n", strerror(errno)); } } Isn't there a way to detect whether the kernel supports the TUNSETOFFLOAD ioctl at all?
On Tue, 2009-11-24 at 12:17 +0100, Pierre Riteau wrote: > On 24 nov. 2009, at 11:28, Mark McLoughlin wrote: > > > On Tue, 2009-11-24 at 10:06 +0100, Pierre Riteau wrote: > >> vnet_hdr is initialized at 1 by default. We need to reset it to 0 if > >> the kernel doesn't support IFF_VNET_HDR. > >> > >> Signed-off-by: Pierre Riteau <Pierre.Riteau@irisa.fr> > > > > Thanks Pierre, I see why this is needed now > > > > Acked-by: Mark McLoughlin <markmc@redhat.com> > > > > Cheers, > > Mark. > > > Thanks for your rapid answer! > > BTW, every time I run qemu I see this error message: > > TUNSETOFFLOAD ioctl() failed: Invalid argument > > It is caused by the piece of code at the end of net/tap-linux.c: > > if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { > offload &= ~TUN_F_UFO; > if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { > fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n", > strerror(errno)); > } > } > > Isn't there a way to detect whether the kernel supports the > TUNSETOFFLOAD ioctl at all? The kernel will set errno to EINVAL if TUNSETOFFLOAD isn't supported, so we could just ignore that case: if (ioctl(fd, TUNSETOFFLOAD, offload) != 0) { offload &= ~TUN_F_UFO; if (ioctl(fd, TUNSETOFFLOAD, offload) != 0 && errno != EINVAL) { fprintf(stderr, "TUNSETOFFLOAD ioctl() failed: %s\n", strerror(errno)); } } The only concern is that we'll also miss out on an error message if EINVAL is set for another reason. Currently, the only other reason if we pass a offload flag not supported by the kernel, but that should never happen. Feel free to send a patch with that change and I'll ack it Thanks, Mark.
diff --git a/net/tap-linux.c b/net/tap-linux.c index 0f621a2..e4f7e27 100644 --- a/net/tap-linux.c +++ b/net/tap-linux.c @@ -52,6 +52,8 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required features & IFF_VNET_HDR) { *vnet_hdr = 1; ifr.ifr_flags |= IFF_VNET_HDR; + } else { + *vnet_hdr = 0; } if (vnet_hdr_required && !*vnet_hdr) {
vnet_hdr is initialized at 1 by default. We need to reset it to 0 if the kernel doesn't support IFF_VNET_HDR. Signed-off-by: Pierre Riteau <Pierre.Riteau@irisa.fr> --- net/tap-linux.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-)