netdev - [PATCH net-next 1/2] sctp: implement memory accounting on tx path

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Message-Id: <57b7c29e160acf1a7e5f86ae8549b23ba8946c4b.1554022192.git.lucien.xin@gmail.com>
Date:   Sun, 31 Mar 2019 16:53:46 +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>, davem@...emloft.net,
        Matteo Croce <mcroce@...hat.com>,
        Vladis Dronov <vdronov@...hat.com>
Subject: [PATCH net-next 1/2] sctp: implement memory accounting on tx path

Now when sending packets, sk_mem_charge() and sk_mem_uncharge() have been
used to set sk_forward_alloc. We just need to call sk_wmem_schedule() to
check if the allocated should be raised, and call sk_mem_reclaim() to
check if the allocated should be reduced when it's under memory pressure.

If sk_wmem_schedule() returns false, which means no memory is allowed to
allocate, it will block and wait for memory to become available.

Note different from tcp, sctp wait_for_buf happens before allocating any
skb, so memory accounting check is done with the whole msg_len before it
too.

Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/sctp/socket.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 6140471..06c6f4a 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -1913,7 +1913,10 @@ static int sctp_sendmsg_to_asoc(struct sctp_association *asoc,
 	if (sctp_wspace(asoc) < (int)msg_len)
 		sctp_prsctp_prune(asoc, sinfo, msg_len - sctp_wspace(asoc));
 
-	if (sctp_wspace(asoc) <= 0) {
+	if (sk_under_memory_pressure(sk))
+		sk_mem_reclaim(sk);
+
+	if (sctp_wspace(asoc) <= 0 || !sk_wmem_schedule(sk, msg_len)) {
 		timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 		err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len);
 		if (err)
@@ -8891,7 +8894,10 @@ static int sctp_wait_for_sndbuf(struct sctp_association *asoc, long *timeo_p,
 			goto do_error;
 		if (signal_pending(current))
 			goto do_interrupted;
-		if ((int)msg_len <= sctp_wspace(asoc))
+		if (sk_under_memory_pressure(sk))
+			sk_mem_reclaim(sk);
+		if ((int)msg_len <= sctp_wspace(asoc) &&
+		    sk_wmem_schedule(sk, msg_len))
 			break;
 
 		/* Let another process have a go.  Since we are going
-- 
2.1.0