thr3ads.net - Linux Virtualization - [PATCH net-next 0/5] virtio-net: Add SCTP checksum offload support [Apr 2018]

If this information is useful, please help other people find it:
Share via:

Vladislav Yasevich

2018-Apr-02 13:40 UTC

[PATCH net-next 0/5] virtio-net: Add SCTP checksum offload support

Now that we have SCTP offload capabilities in the kernel, we can add
them to virtio as well.  First step is SCTP checksum.

We need a new freature in virtio to negotiate this support since
SCTP is excluded with the stardard checksum and requires a little
bit extra.  This series proposes VIRTIO_NET_F_SCTP_CSUM feature bit.

As the "little bit extra",  the kernel uses a new bit in the skb
(skb->csum_not_inet) to determine whether to use standard inet checksum
or the SCTP CRC32c checksum.  This bit has to be communicated between
the host and the guest.  This bit is carried in the vnet header.

Tap and macvtap support is added through an extra feature for the
TUNSETOFFLOAD ioctl.  Additionally macvtap will no correctly
do sctp checksumming if the receive doesn't support SCTP offload.
This also turns on sctp offloading for macvlan devices.

As for the perf numbers, I am seeing about a 5% increase in vm-to-vm
and vm-to-hos throughput which is the same as manually disabling
sctp checksumming,since this is exactly what we are emulatting.
Sending outside the host,  the increase about 2.5-3%.

As for GSO, the way sctp GSO is currently implemented buys us nothing
in added support to virtio.  To add true GSO, would require a lot of
re-work inside of SCTP and would require extensions to the virtio
net header to carry extra sctp data.


Vladislav Yasevich (5):
  virtio: Add support for SCTP checksum offloading
  sctp: Handle sctp packets with CHECKSUM_PARTIAL
  sctp: Build sctp offload support into the base kernel
  tun: Add support for SCTP checksum offload
  macvlan/macvtap: Add support for SCTP checksum offload.

 drivers/net/macvlan.c           |  5 +++--
 drivers/net/tap.c               |  8 +++++---
 drivers/net/tun.c               |  5 +++++
 drivers/net/virtio_net.c        | 10 +++++++---
 include/linux/virtio_net.h      |  6 ++++++
 include/net/sctp/sctp.h         |  5 -----
 include/uapi/linux/if_tun.h     |  1 +
 include/uapi/linux/virtio_net.h |  2 ++
 net/Kconfig                     |  1 +
 net/sctp/Kconfig                |  1 -
 net/sctp/Makefile               |  3 ++-
 net/sctp/input.c                | 11 ++++++++++-
 net/sctp/offload.c              |  4 +++-
 net/sctp/protocol.c             |  3 ---
 14 files changed, 45 insertions(+), 20 deletions(-)

-- 
2.9.5

Vladislav Yasevich

2018-Apr-02 13:40 UTC

head link

[PATCH net-next 1/5] virtio: Add support for SCTP checksum offloading

To support SCTP checksum offloading, we need to add a new feature
to virtio_net, so we can negotiate support between the hypervisor
and the guest.

The signalling to the guest that an alternate checksum needs to
be used is done via a new flag in the virtio_net_hdr.  If the
flag is set, the host will know to perform an alternate checksum
calculation, which right now is only CRC32c.

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 drivers/net/virtio_net.c        | 11 ++++++++---
 include/linux/virtio_net.h      |  6 ++++++
 include/uapi/linux/virtio_net.h |  2 ++
 3 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 7b187ec..b601294 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -2724,9 +2724,14 @@ static int virtnet_probe(struct virtio_device *vdev)
 	/* Do we support "hardware" checksums? */
 	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
 		/* This opens up the world of extra features. */
-		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
+		netdev_features_t sctp = 0;
+
+		if (virtio_has_feature(vdev, VIRTIO_NET_F_SCTP_CSUM))
+			sctp |= NETIF_F_SCTP_CRC;
+
+		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG | sctp;
 		if (csum)
-			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
+			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG | sctp;
 
 		if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
 			dev->hw_features |= NETIF_F_TSO
@@ -2952,7 +2957,7 @@ static struct virtio_device_id id_table[] = {
 };
 
 #define VIRTNET_FEATURES \
-	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM, \
+	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,  VIRTIO_NET_F_SCTP_CSUM, \
 	VIRTIO_NET_F_MAC, \
 	VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6, \
 	VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6, \
diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
index f144216..2e7a64a 100644
--- a/include/linux/virtio_net.h
+++ b/include/linux/virtio_net.h
@@ -39,6 +39,9 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
 
 		if (!skb_partial_csum_set(skb, start, off))
 			return -EINVAL;
+
+		if (hdr->flags & VIRTIO_NET_HDR_F_CSUM_NOT_INET)
+			skb->csum_not_inet = 1;
 	}
 
 	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
@@ -96,6 +99,9 @@ static inline int virtio_net_hdr_from_skb(const struct sk_buff
*skb,
 		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
 	} /* else everything is zero */
 
+	if (skb->csum_not_inet)
+		hdr->flags &= VIRTIO_NET_HDR_F_CSUM_NOT_INET;
+
 	return 0;
 }
 
diff --git a/include/uapi/linux/virtio_net.h b/include/uapi/linux/virtio_net.h
index 5de6ed3..3f279c8 100644
--- a/include/uapi/linux/virtio_net.h
+++ b/include/uapi/linux/virtio_net.h
@@ -36,6 +36,7 @@
 #define VIRTIO_NET_F_GUEST_CSUM	1	/* Guest handles pkts w/ partial csum */
 #define VIRTIO_NET_F_CTRL_GUEST_OFFLOADS 2 /* Dynamic offload configuration. */
 #define VIRTIO_NET_F_MTU	3	/* Initial MTU advice */
+#define VIRTIO_NET_F_SCTP_CSUM  4	/* SCTP checksum offload support */
 #define VIRTIO_NET_F_MAC	5	/* Host has given MAC address. */
 #define VIRTIO_NET_F_GUEST_TSO4	7	/* Guest can handle TSOv4 in. */
 #define VIRTIO_NET_F_GUEST_TSO6	8	/* Guest can handle TSOv6 in. */
@@ -101,6 +102,7 @@ struct virtio_net_config {
 struct virtio_net_hdr_v1 {
 #define VIRTIO_NET_HDR_F_NEEDS_CSUM	1	/* Use csum_start, csum_offset */
 #define VIRTIO_NET_HDR_F_DATA_VALID	2	/* Csum is valid */
+#define VIRTIO_NET_HDR_F_CSUM_NOT_INET  4       /* Checksum is not inet */
 	__u8 flags;
 #define VIRTIO_NET_HDR_GSO_NONE		0	/* Not a GSO frame */
 #define VIRTIO_NET_HDR_GSO_TCPV4	1	/* GSO frame, IPv4 TCP (TSO) */
-- 
2.9.5

Vladislav Yasevich

2018-Apr-02 13:40 UTC

head link

[PATCH net-next 2/5] sctp: Handle sctp packets with CHECKSUM_PARTIAL

With SCTP checksum offload available in virtio, it is now
possible for virtio to receive a sctp packet with CHECKSUM_PARTIAL
set (guest-to-guest traffic).  SCTP doesn't really have a
partial checksum like TCP does because CRC32c can't do partial
additive checksumming.  It's all or nothing.  So an SCTP packet
with CHECKSUM_PARTIAL will have checksum set to 0.  Let SCTP
treat this as a valid checksum if CHECKSUM_PARTIAL is set.

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 net/sctp/input.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/net/sctp/input.c b/net/sctp/input.c
index ba8a6e6..055b8ffa 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -80,8 +80,17 @@ static inline int sctp_rcv_checksum(struct net *net, struct
sk_buff *skb)
 {
 	struct sctphdr *sh = sctp_hdr(skb);
 	__le32 cmp = sh->checksum;
-	__le32 val = sctp_compute_cksum(skb, 0);
+	__le32 val = 0;
 
+	/* In sctp PARTIAL checksum is always 0.  This is a case of
+	 * a packet received from guest that supports checksum offload.
+	 * Assume it's correct as there is really no way to verify,
+	 * and we want to avaoid computing it unnecesarily.
+	 */
+	if (skb->ip_summed == CHECKSUM_PARTIAL)
+		return 0;
+
+	val = sctp_compute_cksum(skb, 0);
 	if (val != cmp) {
 		/* CRC failure, dump it. */
 		__SCTP_INC_STATS(net, SCTP_MIB_CHECKSUMERRORS);
-- 
2.9.5

Vladislav Yasevich

2018-Apr-02 13:40 UTC

head link

[PATCH net-next 3/5] sctp: Build sctp offload support into the base kernel

We need to take the sctp offload out of the sctp module
and add it to the base kernel to support guests that can
support it.  This is similar to how IPv6 offloads are done
and works around kernels that exclude sctp protocol support.

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 include/net/sctp/sctp.h | 5 -----
 net/Kconfig             | 1 +
 net/sctp/Kconfig        | 1 -
 net/sctp/Makefile       | 3 ++-
 net/sctp/offload.c      | 4 +++-
 net/sctp/protocol.c     | 3 ---
 6 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/include/net/sctp/sctp.h b/include/net/sctp/sctp.h
index 72c5b8f..625b45f 100644
--- a/include/net/sctp/sctp.h
+++ b/include/net/sctp/sctp.h
@@ -183,11 +183,6 @@ struct sctp_transport *sctp_epaddr_lookup_transport(
 int __net_init sctp_proc_init(struct net *net);
 
 /*
- * sctp/offload.c
- */
-int sctp_offload_init(void);
-
-/*
  * sctp/stream_sched.c
  */
 void sctp_sched_ops_init(void);
diff --git a/net/Kconfig b/net/Kconfig
index 0428f12..2773f98 100644
--- a/net/Kconfig
+++ b/net/Kconfig
@@ -64,6 +64,7 @@ config INET
 	bool "TCP/IP networking"
 	select CRYPTO
 	select CRYPTO_AES
+	select LIBCRC32C
 	---help---
 	  These are the protocols used on the Internet and on most local
 	  Ethernets. It is highly recommended to say Y here (this will enlarge
diff --git a/net/sctp/Kconfig b/net/sctp/Kconfig
index c740b18..d07477a 100644
--- a/net/sctp/Kconfig
+++ b/net/sctp/Kconfig
@@ -9,7 +9,6 @@ menuconfig IP_SCTP
 	select CRYPTO
 	select CRYPTO_HMAC
 	select CRYPTO_SHA1
-	select LIBCRC32C
 	---help---
 	  Stream Control Transmission Protocol
 
diff --git a/net/sctp/Makefile b/net/sctp/Makefile
index e845e45..ee206ca 100644
--- a/net/sctp/Makefile
+++ b/net/sctp/Makefile
@@ -5,6 +5,7 @@
 
 obj-$(CONFIG_IP_SCTP) += sctp.o
 obj-$(CONFIG_INET_SCTP_DIAG) += sctp_diag.o
+obj-$(CONFIG_INET) += offload.o
 
 sctp-y := sm_statetable.o sm_statefuns.o sm_sideeffect.o \
 	  protocol.o endpointola.o associola.o \
@@ -12,7 +13,7 @@ sctp-y := sm_statetable.o sm_statefuns.o sm_sideeffect.o \
 	  inqueue.o outqueue.o ulpqueue.o \
 	  tsnmap.o bind_addr.o socket.o primitive.o \
 	  output.o input.o debug.o stream.o auth.o \
-	  offload.o stream_sched.o stream_sched_prio.o \
+	  stream_sched.o stream_sched_prio.o \
 	  stream_sched_rr.o stream_interleave.o
 
 sctp_diag-y := diag.o
diff --git a/net/sctp/offload.c b/net/sctp/offload.c
index 123e9f2..c61cbde 100644
--- a/net/sctp/offload.c
+++ b/net/sctp/offload.c
@@ -107,7 +107,7 @@ static const struct skb_checksum_ops crc32c_csum_ops = {
 	.combine = sctp_csum_combine,
 };
 
-int __init sctp_offload_init(void)
+static int __init sctp_offload_init(void)
 {
 	int ret;
 
@@ -127,3 +127,5 @@ int __init sctp_offload_init(void)
 out:
 	return ret;
 }
+
+fs_initcall(sctp_offload_init);
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index a24cde2..46d2b63 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -1479,9 +1479,6 @@ static __init int sctp_init(void)
 	if (status)
 		goto err_v6_add_protocol;
 
-	if (sctp_offload_init() < 0)
-		pr_crit("%s: Cannot add SCTP protocol offload\n", __func__);
-
 out:
 	return status;
 err_v6_add_protocol:
-- 
2.9.5

Vladislav Yasevich

2018-Apr-02 13:40 UTC

head link

[PATCH net-next 4/5] tun: Add support for SCTP checksum offload

Adds a new tun offload flag to allow for SCTP checksum offload.
The flag has to be set by the user and defaults to "no offload".

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 drivers/net/tun.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index a1ba262..263bcbe 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -2719,6 +2719,11 @@ static int set_offload(struct tun_struct *tun, unsigned
long arg)
 		arg &= ~TUN_F_UFO;
 	}
 
+	if (arg & TUN_F_SCTP_CSUM) {
+		features |= NETIF_F_SCTP_CRC;
+		arg &= ~TUN_F_SCTP_CSUM;
+	}
+
 	/* This gives the user a way to test for new features in future by
 	 * trying to set them. */
 	if (arg)
-- 
2.9.5

Vladislav Yasevich

2018-Apr-02 13:40 UTC

head link

[PATCH net-next 5/5] macvlan/macvtap: Add support for SCTP checksum offload.

Since we now have support for software CRC32c offload, turn it on
for macvlan and macvtap devices so that guests can take advantage
of offload SCTP checksums to the host or host hardware.

Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
---
 drivers/net/macvlan.c       | 5 +++--
 drivers/net/tap.c           | 8 +++++---
 include/uapi/linux/if_tun.h | 1 +
 3 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 725f4b4..646b730 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -834,7 +834,7 @@ static struct lock_class_key macvlan_netdev_addr_lock_key;
 
 #define ALWAYS_ON_OFFLOADS \
 	(NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_GSO_SOFTWARE | \
-	 NETIF_F_GSO_ROBUST | NETIF_F_GSO_ENCAP_ALL)
+	 NETIF_F_GSO_ROBUST | NETIF_F_GSO_ENCAP_ALL | NETIF_F_SCTP_CRC)
 
 #define ALWAYS_ON_FEATURES (ALWAYS_ON_OFFLOADS | NETIF_F_LLTX)
 
@@ -842,7 +842,8 @@ static struct lock_class_key macvlan_netdev_addr_lock_key;
 	(NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_FRAGLIST | \
 	 NETIF_F_GSO | NETIF_F_TSO | NETIF_F_LRO | \
 	 NETIF_F_TSO_ECN | NETIF_F_TSO6 | NETIF_F_GRO | NETIF_F_RXCSUM | \
-	 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_VLAN_STAG_FILTER)
+	 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_VLAN_STAG_FILTER | \
+	 NETIF_F_SCTP_CRC)
 
 #define MACVLAN_STATE_MASK \
 	((1<<__LINK_STATE_NOCARRIER) | (1<<__LINK_STATE_DORMANT))
diff --git a/drivers/net/tap.c b/drivers/net/tap.c
index 9b6cb78..2c8512b 100644
--- a/drivers/net/tap.c
+++ b/drivers/net/tap.c
@@ -369,8 +369,7 @@ rx_handler_result_t tap_handle_frame(struct sk_buff **pskb)
 		 *	  check, we either support them all or none.
 		 */
 		if (skb->ip_summed == CHECKSUM_PARTIAL &&
-		    !(features & NETIF_F_CSUM_MASK) &&
-		    skb_checksum_help(skb))
+		    skb_csum_hwoffload_help(skb, features))
 			goto drop;
 		if (ptr_ring_produce(&q->ring, skb))
 			goto drop;
@@ -945,6 +944,9 @@ static int set_offload(struct tap_queue *q, unsigned long
arg)
 		}
 	}
 
+	if (arg & TUN_F_SCTP_CSUM)
+		feature_mask |= NETIF_F_SCTP_CRC;
+
 	/* tun/tap driver inverts the usage for TSO offloads, where
 	 * setting the TSO bit means that the userspace wants to
 	 * accept TSO frames and turning it off means that user space
@@ -1077,7 +1079,7 @@ static long tap_ioctl(struct file *file, unsigned int cmd,
 	case TUNSETOFFLOAD:
 		/* let the user check for future flags */
 		if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
-			    TUN_F_TSO_ECN | TUN_F_UFO))
+			    TUN_F_TSO_ECN | TUN_F_UFO | TUN_F_SCTP_CSUM))
 			return -EINVAL;
 
 		rtnl_lock();
diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
index ee432cd..c3bb282 100644
--- a/include/uapi/linux/if_tun.h
+++ b/include/uapi/linux/if_tun.h
@@ -86,6 +86,7 @@
 #define TUN_F_TSO6	0x04	/* I can handle TSO for IPv6 packets */
 #define TUN_F_TSO_ECN	0x08	/* I can handle TSO with ECN bits. */
 #define TUN_F_UFO	0x10	/* I can handle UFO packets */
+#define TUN_F_SCTP_CSUM 0x20	/* I can handle SCTP checksum offload */
 
 /* Protocol info prepended to the packets (when IFF_NO_PI is not set) */
 #define TUN_PKT_STRIP	0x0001
-- 
2.9.5

David Miller

2018-Apr-02 14:16 UTC

head link

[PATCH net-next 0/5] virtio-net: Add SCTP checksum offload support

From: Vladislav Yasevich <vyasevich at gmail.com>
Date: Mon,  2 Apr 2018 09:40:01 -0400
> Now that we have SCTP offload capabilities in the kernel, we can add
> them to virtio as well.  First step is SCTP checksum.
Vlad, the net-next tree is closed, please resubmit this when the merge window
is over and the net-next tree opens back up.

Thank you.

kbuild test robot

2018-Apr-03 00:49 UTC

head link

[PATCH net-next 4/5] tun: Add support for SCTP checksum offload

Hi Vladislav,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on net-next/master]

url:   
https://github.com/0day-ci/linux/commits/Vladislav-Yasevich/virtio-net-Add-SCTP-checksum-offload-support/20180402-221407
config: m68k-hp300_defconfig (attached as .config)
compiler: m68k-linux-gnu-gcc (Debian 7.2.0-11) 7.2.0
reproduce:
        wget
https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O
~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=m68k 

Note: the
linux-review/Vladislav-Yasevich/virtio-net-Add-SCTP-checksum-offload-support/20180402-221407
HEAD 5e0497a085e70055a1981959802173f4ff05c86b builds fine.
      It only hurts bisectibility.

All errors (new ones prefixed by >>):

   drivers/net/tun.c: In function 'set_offload':>> drivers/net/tun.c:2722:12: error: 'TUN_F_SCTP_CSUM' undeclared
(first use in this function); did you mean 'TUN_F_CSUM'?     if (arg & TUN_F_SCTP_CSUM) {
               ^~~~~~~~~~~~~~~
               TUN_F_CSUM
   drivers/net/tun.c:2722:12: note: each undeclared identifier is reported only
once for each function it appears in

vim +2722 drivers/net/tun.c

  2696	
  2697	/* This is like a cut-down ethtool ops, except done via tun fd so no
  2698	 * privs required. */
  2699	static int set_offload(struct tun_struct *tun, unsigned long arg)
  2700	{
  2701		netdev_features_t features = 0;
  2702	
  2703		if (arg & TUN_F_CSUM) {
  2704			features |= NETIF_F_HW_CSUM;
  2705			arg &= ~TUN_F_CSUM;
  2706	
  2707			if (arg & (TUN_F_TSO4|TUN_F_TSO6)) {
  2708				if (arg & TUN_F_TSO_ECN) {
  2709					features |= NETIF_F_TSO_ECN;
  2710					arg &= ~TUN_F_TSO_ECN;
  2711				}
  2712				if (arg & TUN_F_TSO4)
  2713					features |= NETIF_F_TSO;
  2714				if (arg & TUN_F_TSO6)
  2715					features |= NETIF_F_TSO6;
  2716				arg &= ~(TUN_F_TSO4|TUN_F_TSO6);
  2717			}
  2718	
  2719			arg &= ~TUN_F_UFO;
  2720		}
  2721	> 2722		if (arg & TUN_F_SCTP_CSUM) {  2723			features |= NETIF_F_SCTP_CRC;
  2724			arg &= ~TUN_F_SCTP_CSUM;
  2725		}
  2726	
  2727		/* This gives the user a way to test for new features in future by
  2728		 * trying to set them. */
  2729		if (arg)
  2730			return -EINVAL;
  2731	
  2732		tun->set_features = features;
  2733		tun->dev->wanted_features &= ~TUN_USER_FEATURES;
  2734		tun->dev->wanted_features |= features;
  2735		netdev_update_features(tun->dev);
  2736	
  2737		return 0;
  2738	}
  2739	

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation
-------------- next part --------------
A non-text attachment was scrubbed...
Name: .config.gz
Type: application/gzip
Size: 12572 bytes
Desc: not available
URL:
<http://lists.linuxfoundation.org/pipermail/virtualization/attachments/20180403/e3b321bd/attachment-0001.bin>

Jason Wang

2018-Apr-10 03:17 UTC

head link

[PATCH net-next 1/5] virtio: Add support for SCTP checksum offloading

On 2018?04?02? 21:40, Vladislav Yasevich wrote:> To support SCTP checksum offloading, we need to add a new feature
> to virtio_net, so we can negotiate support between the hypervisor
> and the guest.
>
> The signalling to the guest that an alternate checksum needs to
> be used is done via a new flag in the virtio_net_hdr.  If the
> flag is set, the host will know to perform an alternate checksum
> calculation, which right now is only CRC32c.
>
> Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
> ---
>   drivers/net/virtio_net.c        | 11 ++++++++---
>   include/linux/virtio_net.h      |  6 ++++++
>   include/uapi/linux/virtio_net.h |  2 ++
>   3 files changed, 16 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7b187ec..b601294 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2724,9 +2724,14 @@ static int virtnet_probe(struct virtio_device *vdev)
>   	/* Do we support "hardware" checksums? */
>   	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
>   		/* This opens up the world of extra features. */
> -		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
> +		netdev_features_t sctp = 0;
> +
> +		if (virtio_has_feature(vdev, VIRTIO_NET_F_SCTP_CSUM))
> +			sctp |= NETIF_F_SCTP_CRC;
> +
> +		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG | sctp;
>   		if (csum)
> -			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
> +			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG | sctp;
>   
>   		if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
>   			dev->hw_features |= NETIF_F_TSO
> @@ -2952,7 +2957,7 @@ static struct virtio_device_id id_table[] = {
>   };
>   
>   #define VIRTNET_FEATURES \
> -	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM, \
> +	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,  VIRTIO_NET_F_SCTP_CSUM, \
It looks to me _F_SCTP_CSUM implies the ability of both device and 
driver. Do we still need the flexibility like csum to differ guest/host 
ability like e.g _F_GUEST_SCTP_CSUM?

Thanks
>   	VIRTIO_NET_F_MAC, \
>   	VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6, \
>   	VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
\
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index f144216..2e7a64a 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -39,6 +39,9 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff
*skb,
>   
>   		if (!skb_partial_csum_set(skb, start, off))
>   			return -EINVAL;
> +
> +		if (hdr->flags & VIRTIO_NET_HDR_F_CSUM_NOT_INET)
> +			skb->csum_not_inet = 1;
>   	}
>   
>   	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> @@ -96,6 +99,9 @@ static inline int virtio_net_hdr_from_skb(const struct
sk_buff *skb,
>   		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
>   	} /* else everything is zero */
>   
> +	if (skb->csum_not_inet)
> +		hdr->flags &= VIRTIO_NET_HDR_F_CSUM_NOT_INET;
> +
>   	return 0;
>   }
>   
> diff --git a/include/uapi/linux/virtio_net.h
b/include/uapi/linux/virtio_net.h
> index 5de6ed3..3f279c8 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -36,6 +36,7 @@
>   #define VIRTIO_NET_F_GUEST_CSUM	1	/* Guest handles pkts w/ partial csum
*/
>   #define VIRTIO_NET_F_CTRL_GUEST_OFFLOADS 2 /* Dynamic offload
configuration. */
>   #define VIRTIO_NET_F_MTU	3	/* Initial MTU advice */
> +#define VIRTIO_NET_F_SCTP_CSUM  4	/* SCTP checksum offload support */
>   #define VIRTIO_NET_F_MAC	5	/* Host has given MAC address. */
>   #define VIRTIO_NET_F_GUEST_TSO4	7	/* Guest can handle TSOv4 in. */
>   #define VIRTIO_NET_F_GUEST_TSO6	8	/* Guest can handle TSOv6 in. */
> @@ -101,6 +102,7 @@ struct virtio_net_config {
>   struct virtio_net_hdr_v1 {
>   #define VIRTIO_NET_HDR_F_NEEDS_CSUM	1	/* Use csum_start, csum_offset */
>   #define VIRTIO_NET_HDR_F_DATA_VALID	2	/* Csum is valid */
> +#define VIRTIO_NET_HDR_F_CSUM_NOT_INET  4       /* Checksum is not inet */
>   	__u8 flags;
>   #define VIRTIO_NET_HDR_GSO_NONE		0	/* Not a GSO frame */
>   #define VIRTIO_NET_HDR_GSO_TCPV4	1	/* GSO frame, IPv4 TCP (TSO) */

Michael S. Tsirkin

2018-Apr-11 22:49 UTC

head link

[PATCH net-next 1/5] virtio: Add support for SCTP checksum offloading

On Mon, Apr 02, 2018 at 09:40:02AM -0400, Vladislav Yasevich
wrote:> To support SCTP checksum offloading, we need to add a new feature
> to virtio_net, so we can negotiate support between the hypervisor
> and the guest.
> 
> The signalling to the guest that an alternate checksum needs to
> be used is done via a new flag in the virtio_net_hdr.  If the
> flag is set, the host will know to perform an alternate checksum
> calculation, which right now is only CRC32c.
> 
> Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
> ---
>  drivers/net/virtio_net.c        | 11 ++++++++---
>  include/linux/virtio_net.h      |  6 ++++++
>  include/uapi/linux/virtio_net.h |  2 ++
>  3 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7b187ec..b601294 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2724,9 +2724,14 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	/* Do we support "hardware" checksums? */
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
>  		/* This opens up the world of extra features. */
> -		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
> +		netdev_features_t sctp = 0;
> +
> +		if (virtio_has_feature(vdev, VIRTIO_NET_F_SCTP_CSUM))
> +			sctp |= NETIF_F_SCTP_CRC;
> +
> +		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG | sctp;
>  		if (csum)
> -			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
> +			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG | sctp;
>  
>  		if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
>  			dev->hw_features |= NETIF_F_TSO
> @@ -2952,7 +2957,7 @@ static struct virtio_device_id id_table[] = {
>  };
>  
>  #define VIRTNET_FEATURES \
> -	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM, \
> +	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,  VIRTIO_NET_F_SCTP_CSUM, \
>  	VIRTIO_NET_F_MAC, \
>  	VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6, \
>  	VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
\
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index f144216..2e7a64a 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -39,6 +39,9 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff
*skb,
>  
>  		if (!skb_partial_csum_set(skb, start, off))
>  			return -EINVAL;
> +
> +		if (hdr->flags & VIRTIO_NET_HDR_F_CSUM_NOT_INET)
> +			skb->csum_not_inet = 1;
>  	}
>  
>  	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
> @@ -96,6 +99,9 @@ static inline int virtio_net_hdr_from_skb(const struct
sk_buff *skb,
>  		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
>  	} /* else everything is zero */
>  
> +	if (skb->csum_not_inet)
> +		hdr->flags &= VIRTIO_NET_HDR_F_CSUM_NOT_INET;
> +
>  	return 0;
>  }
>  
> diff --git a/include/uapi/linux/virtio_net.h
b/include/uapi/linux/virtio_net.h
> index 5de6ed3..3f279c8 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -36,6 +36,7 @@
>  #define VIRTIO_NET_F_GUEST_CSUM	1	/* Guest handles pkts w/ partial csum */
>  #define VIRTIO_NET_F_CTRL_GUEST_OFFLOADS 2 /* Dynamic offload
configuration. */
>  #define VIRTIO_NET_F_MTU	3	/* Initial MTU advice */
> +#define VIRTIO_NET_F_SCTP_CSUM  4	/* SCTP checksum offload support */
>  #define VIRTIO_NET_F_MAC	5	/* Host has given MAC address. */
>  #define VIRTIO_NET_F_GUEST_TSO4	7	/* Guest can handle TSOv4 in. */
>  #define VIRTIO_NET_F_GUEST_TSO6	8	/* Guest can handle TSOv6 in. */
Is this a guest or a host checksum? We should differenciate between the
two.

> @@ -101,6 +102,7 @@ struct virtio_net_config {
>  struct virtio_net_hdr_v1 {
>  #define VIRTIO_NET_HDR_F_NEEDS_CSUM	1	/* Use csum_start, csum_offset */
>  #define VIRTIO_NET_HDR_F_DATA_VALID	2	/* Csum is valid */
> +#define VIRTIO_NET_HDR_F_CSUM_NOT_INET  4       /* Checksum is not inet */
>  	__u8 flags;
>  #define VIRTIO_NET_HDR_GSO_NONE		0	/* Not a GSO frame */
>  #define VIRTIO_NET_HDR_GSO_TCPV4	1	/* GSO frame, IPv4 TCP (TSO) */
> -- 
> 2.9.5

Michael S. Tsirkin

2018-Apr-16 17:07 UTC

head link

[PATCH net-next 1/5] virtio: Add support for SCTP checksum offloading

On Mon, Apr 02, 2018 at 09:40:02AM -0400, Vladislav Yasevich
wrote:> To support SCTP checksum offloading, we need to add a new feature
> to virtio_net, so we can negotiate support between the hypervisor
> and the guest.
> 
> The signalling to the guest that an alternate checksum needs to
> be used is done via a new flag in the virtio_net_hdr.  If the
> flag is set, the host will know to perform an alternate checksum
> calculation, which right now is only CRC32c.
> 
> Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
> ---
>  drivers/net/virtio_net.c        | 11 ++++++++---
>  include/linux/virtio_net.h      |  6 ++++++
>  include/uapi/linux/virtio_net.h |  2 ++
>  3 files changed, 16 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 7b187ec..b601294 100644
> --- a/drivers/net/virtio_net.c
> +++ b/drivers/net/virtio_net.c
> @@ -2724,9 +2724,14 @@ static int virtnet_probe(struct virtio_device *vdev)
>  	/* Do we support "hardware" checksums? */
>  	if (virtio_has_feature(vdev, VIRTIO_NET_F_CSUM)) {
>  		/* This opens up the world of extra features. */
> -		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG;
> +		netdev_features_t sctp = 0;
> +
> +		if (virtio_has_feature(vdev, VIRTIO_NET_F_SCTP_CSUM))
> +			sctp |= NETIF_F_SCTP_CRC;
> +
> +		dev->hw_features |= NETIF_F_HW_CSUM | NETIF_F_SG | sctp;
>  		if (csum)
> -			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG;
> +			dev->features |= NETIF_F_HW_CSUM | NETIF_F_SG | sctp;
>  
>  		if (virtio_has_feature(vdev, VIRTIO_NET_F_GSO)) {
>  			dev->hw_features |= NETIF_F_TSO
> @@ -2952,7 +2957,7 @@ static struct virtio_device_id id_table[] = {
>  };
>  
>  #define VIRTNET_FEATURES \
> -	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM, \
> +	VIRTIO_NET_F_CSUM, VIRTIO_NET_F_GUEST_CSUM,  VIRTIO_NET_F_SCTP_CSUM, \
>  	VIRTIO_NET_F_MAC, \
>  	VIRTIO_NET_F_HOST_TSO4, VIRTIO_NET_F_HOST_UFO, VIRTIO_NET_F_HOST_TSO6, \
>  	VIRTIO_NET_F_HOST_ECN, VIRTIO_NET_F_GUEST_TSO4, VIRTIO_NET_F_GUEST_TSO6,
\
> diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> index f144216..2e7a64a 100644
> --- a/include/linux/virtio_net.h
> +++ b/include/linux/virtio_net.h
> @@ -39,6 +39,9 @@ static inline int virtio_net_hdr_to_skb(struct sk_buff
*skb,
>  
>  		if (!skb_partial_csum_set(skb, start, off))
>  			return -EINVAL;
> +
> +		if (hdr->flags & VIRTIO_NET_HDR_F_CSUM_NOT_INET)
> +			skb->csum_not_inet = 1;
>  	}
>  
>  	if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
Looks like we need a feature flag to tell host guest is able to handle this flag
in incoming packets ...

> @@ -96,6 +99,9 @@ static inline int virtio_net_hdr_from_skb(const struct
sk_buff *skb,
>  		hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
>  	} /* else everything is zero */
Is comment above still correct?
>  
> +	if (skb->csum_not_inet)
> +		hdr->flags &= VIRTIO_NET_HDR_F_CSUM_NOT_INET;
> +
... and a separate flag to tell guest it's ok to set this flag in
outgoing packets.


Also - this chunk looks like a hack fixing up a value we
have set incorrectly.

Specifically this clears all flags except VIRTIO_NET_HDR_F_CSUM_NOT_INET.
Why do this at all? Do we really want to clear e.g. NEEDS_CSUM? I think we do
not
since csum_start, csum_offset are set.

Also - what will ever set this flag in the header?

>  	return 0;
>  }
>  
> diff --git a/include/uapi/linux/virtio_net.h
b/include/uapi/linux/virtio_net.h
> index 5de6ed3..3f279c8 100644
> --- a/include/uapi/linux/virtio_net.h
> +++ b/include/uapi/linux/virtio_net.h
> @@ -36,6 +36,7 @@
>  #define VIRTIO_NET_F_GUEST_CSUM	1	/* Guest handles pkts w/ partial csum */
>  #define VIRTIO_NET_F_CTRL_GUEST_OFFLOADS 2 /* Dynamic offload
configuration. */
>  #define VIRTIO_NET_F_MTU	3	/* Initial MTU advice */
> +#define VIRTIO_NET_F_SCTP_CSUM  4	/* SCTP checksum offload support */
>  #define VIRTIO_NET_F_MAC	5	/* Host has given MAC address. */
>  #define VIRTIO_NET_F_GUEST_TSO4	7	/* Guest can handle TSOv4 in. */
>  #define VIRTIO_NET_F_GUEST_TSO6	8	/* Guest can handle TSOv6 in. */
> @@ -101,6 +102,7 @@ struct virtio_net_config {
>  struct virtio_net_hdr_v1 {
>  #define VIRTIO_NET_HDR_F_NEEDS_CSUM	1	/* Use csum_start, csum_offset */
>  #define VIRTIO_NET_HDR_F_DATA_VALID	2	/* Csum is valid */
> +#define VIRTIO_NET_HDR_F_CSUM_NOT_INET  4       /* Checksum is not inet */
Not very informative. Instead, please specify what is it actually.

>  	__u8 flags;
>  #define VIRTIO_NET_HDR_GSO_NONE		0	/* Not a GSO frame */
>  #define VIRTIO_NET_HDR_GSO_TCPV4	1	/* GSO frame, IPv4 TCP (TSO) */
> -- 
> 2.9.5

Michael S. Tsirkin

2018-Apr-16 17:12 UTC

head link

[PATCH net-next 4/5] tun: Add support for SCTP checksum offload

On Mon, Apr 02, 2018 at 09:40:05AM -0400, Vladislav Yasevich
wrote:> Adds a new tun offload flag to allow for SCTP checksum offload.
> The flag has to be set by the user and defaults to "no offload".
> 
> Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
When would user set this flag? Wouldn't that be when
userspace is ready to get SCTP packets without a checksum?
Seems to be this is an indication that when userspace
is qemu running a guest, said guest needs to communicate
the new ability to qemu.
> ---
>  drivers/net/tun.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/net/tun.c b/drivers/net/tun.c
> index a1ba262..263bcbe 100644
> --- a/drivers/net/tun.c
> +++ b/drivers/net/tun.c
> @@ -2719,6 +2719,11 @@ static int set_offload(struct tun_struct *tun,
unsigned long arg)
>  		arg &= ~TUN_F_UFO;
>  	}
>  
> +	if (arg & TUN_F_SCTP_CSUM) {
> +		features |= NETIF_F_SCTP_CRC;
> +		arg &= ~TUN_F_SCTP_CSUM;
> +	}
> +
>  	/* This gives the user a way to test for new features in future by
>  	 * trying to set them. */
>  	if (arg)
> -- 
> 2.9.5

Michael S. Tsirkin

2018-Apr-16 17:14 UTC

head link

[PATCH net-next 5/5] macvlan/macvtap: Add support for SCTP checksum offload.

On Mon, Apr 02, 2018 at 09:40:06AM -0400, Vladislav Yasevich
wrote:> Since we now have support for software CRC32c offload, turn it on
> for macvlan and macvtap devices so that guests can take advantage
> of offload SCTP checksums to the host or host hardware.
> 
> Signed-off-by: Vladislav Yasevich <vyasevic at redhat.com>
> ---
>  drivers/net/macvlan.c       | 5 +++--
>  drivers/net/tap.c           | 8 +++++---
>  include/uapi/linux/if_tun.h | 1 +
>  3 files changed, 9 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
> index 725f4b4..646b730 100644
> --- a/drivers/net/macvlan.c
> +++ b/drivers/net/macvlan.c
> @@ -834,7 +834,7 @@ static struct lock_class_key
macvlan_netdev_addr_lock_key;
>  
>  #define ALWAYS_ON_OFFLOADS \
>  	(NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_GSO_SOFTWARE | \
> -	 NETIF_F_GSO_ROBUST | NETIF_F_GSO_ENCAP_ALL)
> +	 NETIF_F_GSO_ROBUST | NETIF_F_GSO_ENCAP_ALL | NETIF_F_SCTP_CRC)
>  
>  #define ALWAYS_ON_FEATURES (ALWAYS_ON_OFFLOADS | NETIF_F_LLTX)
>  
> @@ -842,7 +842,8 @@ static struct lock_class_key
macvlan_netdev_addr_lock_key;
>  	(NETIF_F_SG | NETIF_F_HW_CSUM | NETIF_F_HIGHDMA | NETIF_F_FRAGLIST | \
>  	 NETIF_F_GSO | NETIF_F_TSO | NETIF_F_LRO | \
>  	 NETIF_F_TSO_ECN | NETIF_F_TSO6 | NETIF_F_GRO | NETIF_F_RXCSUM | \
> -	 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_VLAN_STAG_FILTER)
> +	 NETIF_F_HW_VLAN_CTAG_FILTER | NETIF_F_HW_VLAN_STAG_FILTER | \
> +	 NETIF_F_SCTP_CRC)
>  
>  #define MACVLAN_STATE_MASK \
>  	((1<<__LINK_STATE_NOCARRIER) | (1<<__LINK_STATE_DORMANT))
> diff --git a/drivers/net/tap.c b/drivers/net/tap.c
> index 9b6cb78..2c8512b 100644
> --- a/drivers/net/tap.c
> +++ b/drivers/net/tap.c
> @@ -369,8 +369,7 @@ rx_handler_result_t tap_handle_frame(struct sk_buff
**pskb)
>  		 *	  check, we either support them all or none.
>  		 */
>  		if (skb->ip_summed == CHECKSUM_PARTIAL &&
> -		    !(features & NETIF_F_CSUM_MASK) &&
> -		    skb_checksum_help(skb))
> +		    skb_csum_hwoffload_help(skb, features))
>  			goto drop;
>  		if (ptr_ring_produce(&q->ring, skb))
>  			goto drop;
> @@ -945,6 +944,9 @@ static int set_offload(struct tap_queue *q, unsigned
long arg)
>  		}
>  	}
>  
> +	if (arg & TUN_F_SCTP_CSUM)
> +		feature_mask |= NETIF_F_SCTP_CRC;
> +
>  	/* tun/tap driver inverts the usage for TSO offloads, where
>  	 * setting the TSO bit means that the userspace wants to
>  	 * accept TSO frames and turning it off means that user space
Does not the above comment apply to the new flag too?  It seems that
it's value should be inverted for macvtap, and isn't, here.

> @@ -1077,7 +1079,7 @@ static long tap_ioctl(struct file *file, unsigned int
cmd,
>  	case TUNSETOFFLOAD:
>  		/* let the user check for future flags */
>  		if (arg & ~(TUN_F_CSUM | TUN_F_TSO4 | TUN_F_TSO6 |
> -			    TUN_F_TSO_ECN | TUN_F_UFO))
> +			    TUN_F_TSO_ECN | TUN_F_UFO | TUN_F_SCTP_CSUM))
>  			return -EINVAL;
>  
>  		rtnl_lock();
> diff --git a/include/uapi/linux/if_tun.h b/include/uapi/linux/if_tun.h
> index ee432cd..c3bb282 100644
> --- a/include/uapi/linux/if_tun.h
> +++ b/include/uapi/linux/if_tun.h
> @@ -86,6 +86,7 @@
>  #define TUN_F_TSO6	0x04	/* I can handle TSO for IPv6 packets */
>  #define TUN_F_TSO_ECN	0x08	/* I can handle TSO with ECN bits. */
>  #define TUN_F_UFO	0x10	/* I can handle UFO packets */
> +#define TUN_F_SCTP_CSUM 0x20	/* I can handle SCTP checksum offload */
>  
>  /* Protocol info prepended to the packets (when IFF_NO_PI is not set) */
>  #define TUN_PKT_STRIP	0x0001
Doesn't this belong in the previous patch?
> 2.9.5

Possibly Parallel Threads

Search for more apparently analagous threads

Linux Virtualization - Apr 2018 - [PATCH net-next 0/5] virtio-net: Add SCTP checksum offload support

[PATCH net-next 0/5] virtio-net: Add SCTP checksum offload support

[PATCH net-next 1/5] virtio: Add support for SCTP checksum offloading

[PATCH net-next 2/5] sctp: Handle sctp packets with CHECKSUM_PARTIAL

[PATCH net-next 3/5] sctp: Build sctp offload support into the base kernel

[PATCH net-next 4/5] tun: Add support for SCTP checksum offload

[PATCH net-next 5/5] macvlan/macvtap: Add support for SCTP checksum offload.

[PATCH net-next 0/5] virtio-net: Add SCTP checksum offload support

[PATCH net-next 4/5] tun: Add support for SCTP checksum offload

[PATCH net-next 1/5] virtio: Add support for SCTP checksum offloading

[PATCH net-next 1/5] virtio: Add support for SCTP checksum offloading

[PATCH net-next 1/5] virtio: Add support for SCTP checksum offloading

[PATCH net-next 4/5] tun: Add support for SCTP checksum offload

[PATCH net-next 5/5] macvlan/macvtap: Add support for SCTP checksum offload.

Possibly Parallel Threads