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5d09710925
Historically tun supported two modes of operation: - in default mode, a small number of packets would get queued at the device, the rest would be queued in qdisc - in one queue mode, all packets would get queued at the device This might have made sense up to a point where we made the queue depth for both modes the same and set it to a huge value (500) so unless the consumer is stuck the chance of losing packets is small. Thus in practice both modes behave the same, but the default mode has some problems: - if packets are never consumed, fragments are never orphaned which cases a DOS for sender using zero copy transmit - overrun errors are hard to diagnose: fifo error is incremented only once so you can not distinguish between userspace that is stuck and a transient failure, tcpdump on the device does not show any traffic Userspace solves this simply by enabling IFF_ONE_QUEUE but there seems to be little point in not doing the right thing for everyone, by default. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
101 lines
3.3 KiB
C
101 lines
3.3 KiB
C
/*
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* Universal TUN/TAP device driver.
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* Copyright (C) 1999-2000 Maxim Krasnyansky <max_mk@yahoo.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef _UAPI__IF_TUN_H
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#define _UAPI__IF_TUN_H
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#include <linux/types.h>
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#include <linux/if_ether.h>
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#include <linux/filter.h>
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/* Read queue size */
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#define TUN_READQ_SIZE 500
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/* TUN device flags */
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#define TUN_TUN_DEV 0x0001
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#define TUN_TAP_DEV 0x0002
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#define TUN_TYPE_MASK 0x000f
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#define TUN_FASYNC 0x0010
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#define TUN_NOCHECKSUM 0x0020
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#define TUN_NO_PI 0x0040
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/* This flag has no real effect */
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#define TUN_ONE_QUEUE 0x0080
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#define TUN_PERSIST 0x0100
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#define TUN_VNET_HDR 0x0200
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#define TUN_TAP_MQ 0x0400
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/* Ioctl defines */
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#define TUNSETNOCSUM _IOW('T', 200, int)
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#define TUNSETDEBUG _IOW('T', 201, int)
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#define TUNSETIFF _IOW('T', 202, int)
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#define TUNSETPERSIST _IOW('T', 203, int)
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#define TUNSETOWNER _IOW('T', 204, int)
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#define TUNSETLINK _IOW('T', 205, int)
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#define TUNSETGROUP _IOW('T', 206, int)
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#define TUNGETFEATURES _IOR('T', 207, unsigned int)
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#define TUNSETOFFLOAD _IOW('T', 208, unsigned int)
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#define TUNSETTXFILTER _IOW('T', 209, unsigned int)
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#define TUNGETIFF _IOR('T', 210, unsigned int)
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#define TUNGETSNDBUF _IOR('T', 211, int)
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#define TUNSETSNDBUF _IOW('T', 212, int)
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#define TUNATTACHFILTER _IOW('T', 213, struct sock_fprog)
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#define TUNDETACHFILTER _IOW('T', 214, struct sock_fprog)
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#define TUNGETVNETHDRSZ _IOR('T', 215, int)
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#define TUNSETVNETHDRSZ _IOW('T', 216, int)
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#define TUNSETQUEUE _IOW('T', 217, int)
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/* TUNSETIFF ifr flags */
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#define IFF_TUN 0x0001
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#define IFF_TAP 0x0002
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#define IFF_NO_PI 0x1000
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/* This flag has no real effect */
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#define IFF_ONE_QUEUE 0x2000
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#define IFF_VNET_HDR 0x4000
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#define IFF_TUN_EXCL 0x8000
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#define IFF_MULTI_QUEUE 0x0100
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#define IFF_ATTACH_QUEUE 0x0200
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#define IFF_DETACH_QUEUE 0x0400
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/* Features for GSO (TUNSETOFFLOAD). */
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#define TUN_F_CSUM 0x01 /* You can hand me unchecksummed packets. */
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#define TUN_F_TSO4 0x02 /* I can handle TSO for IPv4 packets */
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#define TUN_F_TSO6 0x04 /* I can handle TSO for IPv6 packets */
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#define TUN_F_TSO_ECN 0x08 /* I can handle TSO with ECN bits. */
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#define TUN_F_UFO 0x10 /* I can handle UFO packets */
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/* Protocol info prepended to the packets (when IFF_NO_PI is not set) */
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#define TUN_PKT_STRIP 0x0001
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struct tun_pi {
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__u16 flags;
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__be16 proto;
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};
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/*
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* Filter spec (used for SETXXFILTER ioctls)
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* This stuff is applicable only to the TAP (Ethernet) devices.
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* If the count is zero the filter is disabled and the driver accepts
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* all packets (promisc mode).
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* If the filter is enabled in order to accept broadcast packets
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* broadcast addr must be explicitly included in the addr list.
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*/
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#define TUN_FLT_ALLMULTI 0x0001 /* Accept all multicast packets */
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struct tun_filter {
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__u16 flags; /* TUN_FLT_ flags see above */
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__u16 count; /* Number of addresses */
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__u8 addr[0][ETH_ALEN];
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};
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#endif /* _UAPI__IF_TUN_H */
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