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Commit 90017acc authored by Marcelo Ricardo Leitner's avatar Marcelo Ricardo Leitner Committed by David S. Miller
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sctp: Add GSO support 



SCTP has this pecualiarity that its packets cannot be just segmented to
(P)MTU. Its chunks must be contained in IP segments, padding respected.
So we can't just generate a big skb, set gso_size to the fragmentation
point and deliver it to IP layer.

This patch takes a different approach. SCTP will now build a skb as it
would be if it was received using GRO. That is, there will be a cover
skb with protocol headers and children ones containing the actual
segments, already segmented to a way that respects SCTP RFCs.

With that, we can tell skb_segment() to just split based on frag_list,
trusting its sizes are already in accordance.

This way SCTP can benefit from GSO and instead of passing several
packets through the stack, it can pass a single large packet.

v2:
- Added support for receiving GSO frames, as requested by Dave Miller.
- Clear skb->cb if packet is GSO (otherwise it's not used by SCTP)
- Added heuristics similar to what we have in TCP for not generating
  single GSO packets that fills cwnd.
v3:
- consider sctphdr size in skb_gso_transport_seglen()
- rebased due to 5c7cdf33 ("gso: Remove arbitrary checks for
  unsupported GSO")

Signed-off-by: default avatarMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Tested-by: default avatarXin Long <lucien.xin@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 3acb50c1

include/linux/netdev_features.h

+5 −2
Original line number Diff line number Diff line
@@ -53,8 +53,9 @@ enum { 
					 *     headers in software.

					 */

	NETIF_F_GSO_TUNNEL_REMCSUM_BIT, /* ... TUNNEL with TSO & REMCSUM */

	NETIF_F_GSO_SCTP_BIT,		/* ... SCTP fragmentation */

	/**/NETIF_F_GSO_LAST =		/* last bit, see GSO_MASK */

		NETIF_F_GSO_TUNNEL_REMCSUM_BIT,

		NETIF_F_GSO_SCTP_BIT,



	NETIF_F_FCOE_CRC_BIT,		/* FCoE CRC32 */

	NETIF_F_SCTP_CRC_BIT,		/* SCTP checksum offload */
@@ -128,6 +129,7 @@ enum { 
#define NETIF_F_TSO_MANGLEID	__NETIF_F(TSO_MANGLEID)

#define NETIF_F_GSO_PARTIAL	 __NETIF_F(GSO_PARTIAL)

#define NETIF_F_GSO_TUNNEL_REMCSUM __NETIF_F(GSO_TUNNEL_REMCSUM)

#define NETIF_F_GSO_SCTP	__NETIF_F(GSO_SCTP)

#define NETIF_F_HW_VLAN_STAG_FILTER __NETIF_F(HW_VLAN_STAG_FILTER)

#define NETIF_F_HW_VLAN_STAG_RX	__NETIF_F(HW_VLAN_STAG_RX)

#define NETIF_F_HW_VLAN_STAG_TX	__NETIF_F(HW_VLAN_STAG_TX)
@@ -166,7 +168,8 @@ enum { 
				 NETIF_F_FSO)



/* List of features with software fallbacks. */

#define NETIF_F_GSO_SOFTWARE	(NETIF_F_ALL_TSO | NETIF_F_UFO)

#define NETIF_F_GSO_SOFTWARE	(NETIF_F_ALL_TSO | NETIF_F_UFO | \

				 NETIF_F_GSO_SCTP)



/*

 * If one device supports one of these features, then enable them

include/linux/netdevice.h

+1 −0
Original line number Diff line number Diff line
@@ -4012,6 +4012,7 @@ static inline bool net_gso_ok(netdev_features_t features, int gso_type) 
	BUILD_BUG_ON(SKB_GSO_UDP_TUNNEL_CSUM != (NETIF_F_GSO_UDP_TUNNEL_CSUM >> NETIF_F_GSO_SHIFT));

	BUILD_BUG_ON(SKB_GSO_PARTIAL != (NETIF_F_GSO_PARTIAL >> NETIF_F_GSO_SHIFT));

	BUILD_BUG_ON(SKB_GSO_TUNNEL_REMCSUM != (NETIF_F_GSO_TUNNEL_REMCSUM >> NETIF_F_GSO_SHIFT));

	BUILD_BUG_ON(SKB_GSO_SCTP    != (NETIF_F_GSO_SCTP >> NETIF_F_GSO_SHIFT));



	return (features & feature) == feature;

}

include/linux/skbuff.h

+2 −0
Original line number Diff line number Diff line
@@ -487,6 +487,8 @@ enum { 
	SKB_GSO_PARTIAL = 1 << 13,



	SKB_GSO_TUNNEL_REMCSUM = 1 << 14,



	SKB_GSO_SCTP = 1 << 15,

};



#if BITS_PER_LONG > 32

include/net/sctp/sctp.h

+4 −0
Original line number Diff line number Diff line
@@ -186,6 +186,10 @@ void sctp_assocs_proc_exit(struct net *net); 
int sctp_remaddr_proc_init(struct net *net);

void sctp_remaddr_proc_exit(struct net *net);



/*

 * sctp/offload.c

 */

int sctp_offload_init(void);



/*

 * Module global variables

include/net/sctp/structs.h

+5 −0
Original line number Diff line number Diff line
@@ -566,6 +566,9 @@ struct sctp_chunk { 
	/* This points to the sk_buff containing the actual data.  */

	struct sk_buff *skb;



	/* In case of GSO packets, this will store the head one */

	struct sk_buff *head_skb;



	/* These are the SCTP headers by reverse order in a packet.

	 * Note that some of these may happen more than once.  In that

	 * case, we point at the "current" one, whatever that means
@@ -696,6 +699,8 @@ struct sctp_packet { 
	size_t overhead;

	/* This is the total size of all chunks INCLUDING padding.  */

	size_t size;

	/* This is the maximum size this packet may have */

	size_t max_size;



	/* The packet is destined for this transport address.

	 * The function we finally use to pass down to the next lower