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Date: Sat, 29 Apr 2017 13:18:34 -0700
From: Tom Herbert <tom@...bertland.com>
To: Davide Caratti <dcaratti@...hat.com>
Cc: Alexander Duyck <alexander.duyck@...il.com>,
David Laight <David.Laight@...lab.com>,
"David S . Miller" <davem@...emloft.net>,
Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
Linux Kernel Network Developers <netdev@...r.kernel.org>,
"linux-sctp @ vger . kernel . org" <linux-sctp@...r.kernel.org>
Subject: Re: [PATCH RFC net-next v4 4/7] net: use skb->csum_not_inet to
identify packets needing crc32c
On Thu, Apr 20, 2017 at 6:38 AM, Davide Caratti <dcaratti@...hat.com> wrote:
> skb->csum_not_inet carries the indication on which algorithm is needed to
> compute checksum on skb in the transmit path, when skb->ip_summed is equal
> to CHECKSUM_PARTIAL. If skb carries a SCTP packet and crc32c hasn't been
> yet written in L4 header, skb->csum_not_inet is assigned to 1; otherwise,
> assume Internet Checksum is needed and thus set skb->csum_not_inet to 0.
>
> Suggested-by: Tom Herbert <tom@...bertland.com>
> Signed-off-by: Davide Caratti <dcaratti@...hat.com>
> ---
> include/linux/skbuff.h | 16 +++++++++-------
> net/core/dev.c | 1 +
> net/sched/act_csum.c | 1 +
> net/sctp/offload.c | 1 +
> net/sctp/output.c | 1 +
> 5 files changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 927309e..419f4c8 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -189,12 +189,13 @@
> *
> * NETIF_F_SCTP_CRC - This feature indicates that a device is capable of
> * offloading the SCTP CRC in a packet. To perform this offload the stack
> - * will set ip_summed to CHECKSUM_PARTIAL and set csum_start and csum_offset
> - * accordingly. Note the there is no indication in the skbuff that the
> - * CHECKSUM_PARTIAL refers to an SCTP checksum, a driver that supports
> - * both IP checksum offload and SCTP CRC offload must verify which offload
> - * is configured for a packet presumably by inspecting packet headers; in
> - * case, skb_crc32c_csum_help is provided to compute CRC on SCTP packets.
> + * will set set csum_start and csum_offset accordingly, set ip_summed to
> + * CHECKSUM_PARTIAL and set csum_not_inet to 1, to provide an indication in
> + * the skbuff that the CHECKSUM_PARTIAL refers to CRC32c.
> + * A driver that supports both IP checksum offload and SCTP CRC32c offload
> + * must verify which offload is configured for a packet by testing the
> + * value of skb->csum_not_inet; skb_crc32c_csum_help is provided to resolve
> + * CHECKSUM_PARTIAL on skbs where csum_not_inet is set to 1.
> *
> * NETIF_F_FCOE_CRC - This feature indicates that a device is capable of
> * offloading the FCOE CRC in a packet. To perform this offload the stack
> @@ -615,6 +616,7 @@ static inline bool skb_mstamp_after(const struct skb_mstamp *t1,
> * @wifi_acked_valid: wifi_acked was set
> * @wifi_acked: whether frame was acked on wifi or not
> * @no_fcs: Request NIC to treat last 4 bytes as Ethernet FCS
> + * @csum_not_inet: use CRC32c to resolve CHECKSUM_PARTIAL
> * @dst_pending_confirm: need to confirm neighbour
> * @napi_id: id of the NAPI struct this skb came from
> * @secmark: security marking
> @@ -743,7 +745,7 @@ struct sk_buff {
> __u8 csum_valid:1;
> __u8 csum_complete_sw:1;
> __u8 csum_level:2;
> - __u8 __csum_bad_unused:1; /* one bit hole */
> + __u8 csum_not_inet:1;
>
> __u8 dst_pending_confirm:1;
> #ifdef CONFIG_IPV6_NDISC_NODETYPE
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 77a2d73..9f56f87 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -2642,6 +2642,7 @@ int skb_crc32c_csum_help(struct sk_buff *skb)
> }
> *(__le32 *)(skb->data + offset) = crc32c_csum;
> skb->ip_summed = CHECKSUM_NONE;
> + skb->csum_not_inet = 0;
> out:
> return ret;
> }
> diff --git a/net/sched/act_csum.c b/net/sched/act_csum.c
> index ab6fdbd..3317a2f 100644
> --- a/net/sched/act_csum.c
> +++ b/net/sched/act_csum.c
> @@ -350,6 +350,7 @@ static int tcf_csum_sctp(struct sk_buff *skb, unsigned int ihl,
> sctph->checksum = sctp_compute_cksum(skb,
> skb_network_offset(skb) + ihl);
> skb->ip_summed = CHECKSUM_NONE;
> + skb->csum_not_inet = 0;
>
> return 1;
> }
> diff --git a/net/sctp/offload.c b/net/sctp/offload.c
> index 378f462..ef156ac 100644
> --- a/net/sctp/offload.c
> +++ b/net/sctp/offload.c
> @@ -35,6 +35,7 @@
> static __le32 sctp_gso_make_checksum(struct sk_buff *skb)
> {
> skb->ip_summed = CHECKSUM_NONE;
> + skb->csum_not_inet = 0;
> return sctp_compute_cksum(skb, skb_transport_offset(skb));
> }
>
> diff --git a/net/sctp/output.c b/net/sctp/output.c
> index 1409a87..e2edf2e 100644
> --- a/net/sctp/output.c
> +++ b/net/sctp/output.c
> @@ -538,6 +538,7 @@ static int sctp_packet_pack(struct sctp_packet *packet,
> } else {
> chksum:
> head->ip_summed = CHECKSUM_PARTIAL;
> + head->csum_not_inet = 1;
> head->csum_start = skb_transport_header(head) - head->head;
> head->csum_offset = offsetof(struct sctphdr, checksum);
> }
> --
> 2.7.4
>
Looks great!
Acked-by: Tom Herbert <tom@...bertland.com>
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