netdev - [PATCH 1/3] skbuff: Avoid sleeping in skb_send_sock

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Message-Id: <E1eZcnk-0002Uw-F7@gondolin.hengli.com.au>
Date:   Fri, 12 Jan 2018 00:21:48 +1100
From:   Herbert Xu <herbert@...dor.apana.org.au>
To:     Steffen Klassert <steffen.klassert@...unet.com>,
        netdev@...r.kernel.org
Subject: [PATCH 1/3] skbuff: Avoid sleeping in skb_send_sock_locked

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>
---

 net/core/skbuff.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 6b0ff39..8197b7a 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2279,6 +2279,7 @@ 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)