netdev - [PATCHv3 net-next 11/16] sctp: call sk_setup_caps in sctp_packet

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Date:   Tue, 13 Oct 2020 15:27:36 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org
Cc:     Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        Michael Tuexen <tuexen@...muenster.de>, davem@...emloft.net,
        gnault@...hat.com, pabeni@...hat.com,
        willemdebruijn.kernel@...il.com
Subject: [PATCHv3 net-next 11/16] sctp: call sk_setup_caps in sctp_packet_transmit instead

sk_setup_caps() was originally called in Commit 90017accff61 ("sctp:
Add GSO support"), as:

  "We have to refresh this in case we are xmiting to more than one
   transport at a time"

This actually happens in the loop of sctp_outq_flush_transports(),
and it shouldn't be tied to gso, so move it out of gso part and
before sctp_packet_pack().

Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/sctp/output.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/net/sctp/output.c b/net/sctp/output.c
index 1441eaf..fb16500 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -508,12 +508,6 @@ static int sctp_packet_pack(struct sctp_packet *packet,
 					sizeof(struct inet6_skb_parm)));
 		skb_shinfo(head)->gso_segs = pkt_count;
 		skb_shinfo(head)->gso_size = GSO_BY_FRAGS;
-		rcu_read_lock();
-		if (skb_dst(head) != tp->dst) {
-			dst_hold(tp->dst);
-			sk_setup_caps(sk, tp->dst);
-		}
-		rcu_read_unlock();
 		goto chksum;
 	}
 
@@ -593,6 +587,13 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
 	}
 	skb_dst_set(head, dst);
 
+	rcu_read_lock();
+	if (__sk_dst_get(sk) != tp->dst) {
+		dst_hold(tp->dst);
+		sk_setup_caps(sk, tp->dst);
+	}
+	rcu_read_unlock();
+
 	/* pack up chunks */
 	pkt_count = sctp_packet_pack(packet, head, gso, gfp);
 	if (!pkt_count) {
-- 
2.1.0