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@xxxxxxxxxxxxxxx>
Signed-off-by: Davide Caratti <dcaratti@xxxxxxxxxx>
---
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
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