Hi Rusty,
Sorry for delay in reply. I totally missed this one. Need to fix my mail
filters.
See below.
Rusty Russell wrote:
> (No real change, just updated with new bits)
>
> The problem with introducing IFF_RECV_CSUM and IFF_RECV_GSO is that
> they need to set dev->features to enable GSO and/or checksumming,
> which is supposed to be done before register_netdevice(), ie. as part
> of TUNSETIFF.
>
> Unfortunately, TUNSETIFF has always just ignored flags it doesn't understand,
> so there's no good way of detecting whether the kernel supports IFF_GSO_HDR.
>
> This patch implements a TUNGETFEATURES ioctl which returns all the valid IFF
> flags. It could be extended later to include other features.
>
> Here's an example program which uses it:
>
> #include <linux/if_tun.h>
> #include <sys/types.h>
> #include <sys/ioctl.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <err.h>
> #include <stdio.h>
>
> static struct {
> unsigned int flag;
> const char *name;
> } known_flags[] = {
> { IFF_TUN, "TUN" },
> { IFF_TAP, "TAP" },
> { IFF_NO_PI, "NO_PI" },
> { IFF_ONE_QUEUE, "ONE_QUEUE" },
> { IFF_VIRTIO_HDR, "VIRTIO_HDR" },
> { IFF_RECV_CSUM, "RECV_CSUM" },
> { IFF_RECV_GSO, "RECV_GSO" },
> };
>
> int main()
> {
> unsigned int features, i;
>
> int netfd = open("/dev/net/tun", O_RDWR);
> if (netfd < 0)
> err(1, "Opening /dev/net/tun");
>
> if (ioctl(netfd, TUNGETFEATURES, &features) != 0) {
> printf("Kernel does not support TUNGETFEATURES, guessing\n");
> features = (IFF_TUN|IFF_TAP|IFF_NO_PI|IFF_ONE_QUEUE);
> }
> printf("Available features are: ");
> for (i = 0; i < sizeof(known_flags)/sizeof(known_flags[0]); i++) {
> if (features & known_flags[i].flag) {
> features &= ~known_flags[i].flag;
> printf("%s ", known_flags[i].name);
> }
> }
> if (features)
> printf("(UNKNOWN %#x)", features);
> printf("\n");
> return 0;
> }
>
> Signed-off-by: Rusty Russell <[EMAIL PROTECTED]>
> ---
> drivers/net/tun.c | 9 +++++++++
> include/linux/if_tun.h | 3 +++
> 2 files changed, 12 insertions(+)
>
> diff -r c0e7a8b99325 drivers/net/tun.c
> --- a/drivers/net/tun.c Wed Jan 23 20:12:51 2008 +1100
> +++ b/drivers/net/tun.c Wed Jan 23 20:17:28 2008 +1100
> @@ -790,6 +790,15 @@ static int tun_chr_ioctl(struct inode *i
> return 0;
> }
>
> + if (cmd == TUNGETFEATURES) {
> + /* Currently this just means: "what IFF flags are valid?".
> + * This is needed because we never checked for invalid flags on
> + * TUNSETIFF. This was introduced with IFF_GSO_HDR, so if a
> + * kernel doesn't have this ioctl, it doesn't have GSO header
> + * support. */
> + return put_user(IFF_ALL_FLAGS, (unsigned int __user*)argp);
> + }
> +
> if (!tun)
> return -EBADFD;
>
> diff -r c0e7a8b99325 include/linux/if_tun.h
> --- a/include/linux/if_tun.h Wed Jan 23 20:12:51 2008 +1100
> +++ b/include/linux/if_tun.h Wed Jan 23 20:17:28 2008 +1100
> @@ -82,6 +82,7 @@ struct tun_struct {
> #define TUNSETOWNER _IOW('T', 204, int)
> #define TUNSETLINK _IOW('T', 205, int)
> #define TUNSETGROUP _IOW('T', 206, int)
> +#define TUNGETFEATURES _IOR('T', 207, unsigned int)
>
> /* TUNSETIFF ifr flags */
> #define IFF_TUN 0x0001
> @@ -91,6 +92,8 @@ struct tun_struct {
> #define IFF_VIRTIO_HDR 0x4000
> #define IFF_RECV_CSUM 0x8000
> #define IFF_RECV_GSO 0x0800
> +#define IFF_ALL_FLAGS (IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE | \
> + IFF_VIRTIO_HDR | IFF_RECV_CSUM | IFF_RECV_GSO)
>
> struct tun_pi {
> unsigned short flags;
Definitely Ack this one. Query interface makes perfect sense.
I'll reply to the GSO itself shortly.
I was going to create git tree for tun changes for awhile now. Looks like the
time has come.
I'll do that asap.
Thanx
Max
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