@@ -119,7 +119,13 @@ int sctp_rcv(struct sk_buff *skb)
skb_transport_offset(skb))
goto discard_it;
- if (!pskb_may_pull(skb, sizeof(struct sctphdr)))
+ /* If the packet is fragmented and we need to do crc checking,
+ * it's better to just linearize it otherwise crc computing
+ * takes longer.
+ */
+ if ((!(skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) &&
+ skb_linearize(skb)) ||
+ !pskb_may_pull(skb, sizeof(struct sctphdr)))
goto discard_it;
/* Pull up the IP header. */
@@ -1177,9 +1183,6 @@ static struct sctp_association *__sctp_rcv_lookup_harder(struct net *net,
if ((skb_shinfo(skb)->gso_type & SKB_GSO_SCTP) == SKB_GSO_SCTP)
return NULL;
- if (skb_linearize(skb))
- return NULL;
-
ch = (sctp_chunkhdr_t *) skb->data;
/* The code below will attempt to walk the chunk and extract
@@ -170,19 +170,6 @@ next_chunk:
chunk = list_entry(entry, struct sctp_chunk, list);
- /* Linearize if it's not GSO */
- if ((skb_shinfo(chunk->skb)->gso_type & SKB_GSO_SCTP) != SKB_GSO_SCTP &&
- skb_is_nonlinear(chunk->skb)) {
- if (skb_linearize(chunk->skb)) {
- __SCTP_INC_STATS(dev_net(chunk->skb->dev), SCTP_MIB_IN_PKT_DISCARDS);
- sctp_chunk_free(chunk);
- goto next_chunk;
- }
-
- /* Update sctp_hdr as it probably changed */
- chunk->sctp_hdr = sctp_hdr(chunk->skb);
- }
-
if ((skb_shinfo(chunk->skb)->gso_type & SKB_GSO_SCTP) == SKB_GSO_SCTP) {
/* GSO-marked skbs but without frags, handle
* them normally
Because otherwise when crc computation is still needed it's way more expensive than on a linear buffer to the point that it affects performance. It's so expensive that netperf test gives a perf output as below: Overhead Command Shared Object Symbol 18,62% netserver [kernel.vmlinux] [k] crc32_generic_shift 2,57% netserver [kernel.vmlinux] [k] __pskb_pull_tail 1,94% netserver [kernel.vmlinux] [k] fib_table_lookup 1,90% netserver [kernel.vmlinux] [k] copy_user_enhanced_fast_string 1,66% swapper [kernel.vmlinux] [k] intel_idle 1,63% netserver [kernel.vmlinux] [k] _raw_spin_lock 1,59% netserver [sctp] [k] sctp_packet_transmit 1,55% netserver [kernel.vmlinux] [k] memcpy_erms 1,42% netserver [sctp] [k] sctp_rcv # netperf -H 192.168.10.1 -l 10 -t SCTP_STREAM -cC -- -m 12000 SCTP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.10.1 () port 0 AF_INET Recv Send Send Utilization Service Demand Socket Socket Message Elapsed Send Recv Send Recv Size Size Size Time Throughput local remote local remote bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB 212992 212992 12000 10.00 3016.42 2.88 3.78 1.874 2.462 After patch: Overhead Command Shared Object Symbol 2,75% netserver [kernel.vmlinux] [k] memcpy_erms 2,63% netserver [kernel.vmlinux] [k] copy_user_enhanced_fast_string 2,39% netserver [kernel.vmlinux] [k] fib_table_lookup 2,04% netserver [kernel.vmlinux] [k] __pskb_pull_tail 1,91% netserver [kernel.vmlinux] [k] _raw_spin_lock 1,91% netserver [sctp] [k] sctp_packet_transmit 1,72% netserver [mlx4_en] [k] mlx4_en_process_rx_cq 1,68% netserver [sctp] [k] sctp_rcv # netperf -H 192.168.10.1 -l 10 -t SCTP_STREAM -cC -- -m 12000 SCTP STREAM TEST from 0.0.0.0 (0.0.0.0) port 0 AF_INET to 192.168.10.1 () port 0 AF_INET Recv Send Send Utilization Service Demand Socket Socket Message Elapsed Send Recv Send Recv Size Size Size Time Throughput local remote local remote bytes bytes bytes secs. 10^6bits/s % S % S us/KB us/KB 212992 212992 12000 10.00 3681.77 3.83 3.46 2.045 1.849 Fixes: 3acb50c18d8d ("sctp: delay as much as possible skb_linearize") Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> --- v1->v2: - Fixed changelog referencing other kernel, spotted by Daniel Borkmann. Please consider this for stable, as v4.7 is affected. Thanks! net/sctp/input.c | 11 +++++++---- net/sctp/inqueue.c | 13 ------------- 2 files changed, 7 insertions(+), 17 deletions(-)