netdev - [PATCH RFC ipsec-next 2/7] skbuff: Avoid sleeping in skb_send_sock

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Message-Id: <23a871790d07db86a869e98118cedd703c42b6c2.1561457281.git.sd@queasysnail.net>
Date:   Tue, 25 Jun 2019 12:11:35 +0200
From:   Sabrina Dubroca <sd@...asysnail.net>
To:     netdev@...r.kernel.org
Cc:     Herbert Xu <herbert@...dor.apana.org.au>,
        Steffen Klassert <steffen.klassert@...unet.com>,
        Sabrina Dubroca <sd@...asysnail.net>
Subject: [PATCH RFC ipsec-next 2/7] skbuff: Avoid sleeping in skb_send_sock_locked

From: Herbert Xu <herbert@...dor.apana.org.au>

For a function that needs to be called with the socket spinlock
held, sleeping would seem to be a bad idea.  This function does
in fact avoid sleeping when calling kernel_sendpage_locked on the
page part of the skb.  However, it doesn't do that when sending
the linear part.  Resulting in sleeping when the socket send buffer
is full.

This patch fixes it by setting the MSG_DONTWAIT flag when calling
kernel_sendmsg_locked.

Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>
Signed-off-by: Sabrina Dubroca <sd@...asysnail.net>
---
 net/core/skbuff.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index b50a5e3ac4e4..f863c7ef417c 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2367,6 +2367,7 @@ int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset,
 		kv.iov_base = skb->data + offset;
 		kv.iov_len = slen;
 		memset(&msg, 0, sizeof(msg));
+		msg.msg_flags = MSG_DONTWAIT;
 
 		ret = kernel_sendmsg_locked(sk, &msg, &kv, 1, slen);
 		if (ret <= 0)
-- 
2.22.0