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Date: Fri, 28 Nov 2014 08:15:32 +0008
From: Jason Wang <jasowang@...hat.com>
To: "Michael S. Tsirkin" <mst@...hat.com>
Cc: linux-kernel@...r.kernel.org, David Miller <davem@...emloft.net>,
cornelia.huck@...ibm.com, rusty@....ibm.com, nab@...ux-iscsi.org,
pbonzini@...hat.com, thuth@...ux.vnet.ibm.com,
dahi@...ux.vnet.ibm.com, Zhi Yong Wu <wuzhy@...ux.vnet.ibm.com>,
Ben Hutchings <ben@...adent.org.uk>,
Herbert Xu <herbert@...dor.apana.org.au>,
Tom Herbert <therbert@...gle.com>,
Masatake YAMATO <yamato@...hat.com>, Xi Wang <xii@...gle.com>,
netdev@...r.kernel.org, linux-api@...r.kernel.org
Subject: Re: [PATCH v6 37/46] tun: move internal flag defines out of uapi
On Fri, Nov 28, 2014 at 4:10 AM, Michael S. Tsirkin <mst@...hat.com>
wrote:
> TUN_ flags are internal and never exposed
> to userspace. Any application using it is almost
> certainly buggy.
>
> Move them out to tun.c, we'll remove them in follow-up patches.
>
> Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
> ---
> include/uapi/linux/if_tun.h | 16 ++--------
> drivers/net/tun.c | 74
> ++++++++++++++-------------------------------
> 2 files changed, 26 insertions(+), 64 deletions(-)
>
> diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
> index e9502dd..277a260 100644
> --- a/include/uapi/linux/if_tun.h
> +++ b/include/uapi/linux/if_tun.h
> @@ -22,21 +22,11 @@
>
> /* Read queue size */
> #define TUN_READQ_SIZE 500
> -
> -/* TUN device flags */
> -#define TUN_TUN_DEV 0x0001
> -#define TUN_TAP_DEV 0x0002
> +/* TUN device type flags: deprecated. Use IFF_TUN/IFF_TAP instead. */
> +#define TUN_TUN_DEV IFF_TUN
> +#define TUN_TAP_DEV IFF_TAP
> #define TUN_TYPE_MASK 0x000f
>
> -#define TUN_FASYNC 0x0010
> -#define TUN_NOCHECKSUM 0x0020
> -#define TUN_NO_PI 0x0040
> -/* This flag has no real effect */
> -#define TUN_ONE_QUEUE 0x0080
> -#define TUN_PERSIST 0x0100
> -#define TUN_VNET_HDR 0x0200
> -#define TUN_TAP_MQ 0x0400
> -
> /* Ioctl defines */
> #define TUNSETNOCSUM _IOW('T', 200, int)
> #define TUNSETDEBUG _IOW('T', 201, int)
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index 9dd3746..bc89d07 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -103,6 +103,21 @@ do { \
> } while (0)
> #endif
>
> +/* TUN device flags */
> +
> +/* IFF_ATTACH_QUEUE is never stored in device flags,
> + * overload it to mean fasync when stored there.
> + */
> +#define TUN_FASYNC IFF_ATTACH_QUEUE
> +#define TUN_NO_PI IFF_NO_PI
> +/* This flag has no real effect */
> +#define TUN_ONE_QUEUE IFF_ONE_QUEUE
> +#define TUN_PERSIST IFF_PERSIST
> +#define TUN_VNET_HDR IFF_VNET_HDR
> +#define TUN_TAP_MQ IFF_MULTI_QUEUE
> +
> +#define TUN_FEATURES (IFF_NO_PI | IFF_ONE_QUEUE | IFF_VNET_HDR | \
> + IFF_MULTI_QUEUE)
> #define GOODCOPY_LEN 128
>
> #define FLT_EXACT_COUNT 8
> @@ -1521,32 +1536,7 @@ static struct proto tun_proto = {
>
> static int tun_flags(struct tun_struct *tun)
> {
> - int flags = 0;
> -
> - if (tun->flags & TUN_TUN_DEV)
> - flags |= IFF_TUN;
> - else
> - flags |= IFF_TAP;
> -
> - if (tun->flags & TUN_NO_PI)
> - flags |= IFF_NO_PI;
> -
> - /* This flag has no real effect. We track the value for backwards
> - * compatibility.
> - */
> - if (tun->flags & TUN_ONE_QUEUE)
> - flags |= IFF_ONE_QUEUE;
> -
> - if (tun->flags & TUN_VNET_HDR)
> - flags |= IFF_VNET_HDR;
> -
> - if (tun->flags & TUN_TAP_MQ)
> - flags |= IFF_MULTI_QUEUE;
> -
> - if (tun->flags & TUN_PERSIST)
> - flags |= IFF_PERSIST;
> -
> - return flags;
> + return tun->flags & (TUN_FEATURES | IFF_PERSIST | IFF_TUN |
> IFF_TAP);
> }
>
> static ssize_t tun_show_flags(struct device *dev, struct
> device_attribute *attr,
> @@ -1706,28 +1696,8 @@ static int tun_set_iff(struct net *net, struct
> file *file, struct ifreq *ifr)
>
> tun_debug(KERN_INFO, tun, "tun_set_iff\n");
>
> - if (ifr->ifr_flags & IFF_NO_PI)
> - tun->flags |= TUN_NO_PI;
> - else
> - tun->flags &= ~TUN_NO_PI;
> -
> - /* This flag has no real effect. We track the value for backwards
> - * compatibility.
> - */
> - if (ifr->ifr_flags & IFF_ONE_QUEUE)
> - tun->flags |= TUN_ONE_QUEUE;
> - else
> - tun->flags &= ~TUN_ONE_QUEUE;
> -
> - if (ifr->ifr_flags & IFF_VNET_HDR)
> - tun->flags |= TUN_VNET_HDR;
> - else
> - tun->flags &= ~TUN_VNET_HDR;
> -
> - if (ifr->ifr_flags & IFF_MULTI_QUEUE)
> - tun->flags |= TUN_TAP_MQ;
> - else
> - tun->flags &= ~TUN_TAP_MQ;
> + tun->flags = (tun->flags & ~TUN_FEATURES) |
> + (ifr->ifr_flags & TUN_FEATURES);
>
> /* Make sure persistent devices do not get stuck in
> * xoff state.
> @@ -1890,9 +1860,11 @@ static long __tun_chr_ioctl(struct file *file,
> unsigned int cmd,
> if (cmd == TUNGETFEATURES) {
> /* Currently this just means: "what IFF flags are valid?".
> * This is needed because we never checked for invalid flags on
> - * TUNSETIFF. */
> - return put_user(IFF_TUN | IFF_TAP | IFF_NO_PI | IFF_ONE_QUEUE |
> - IFF_VNET_HDR | IFF_MULTI_QUEUE,
> + * TUNSETIFF. Why do we report IFF_TUN and IFF_TAP which are
> + * not legal for TUNSETIFF here? It's probably a bug, but it
> + * doesn't seem to be worth fixing.
> + */
The question is not very clear. IFF_TUN and IFF_TAP are legal for
ifr.ifr_flags during TUNSETIFF. No?
>
> + return put_user(IFF_TUN | IFF_TAP | TUN_FEATURES,
> (unsigned int __user*)argp);
> } else if (cmd == TUNSETQUEUE)
> return tun_set_queue(file, &ifr);
> --
> MST
>
> --
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