On 29/06/2021 17:41, Xin Long wrote:
On Tue, Jun 29, 2021 at 3:57 PM Jon Maloy <jma...@redhat.com> wrote:
[...]
Yes, Jon, I mean the opposite.
when MSG_EOR is set, we will go with what this patch does,
but to delete MSG_EOR if this is not the last part of the data,
and keep MSG_EOR if this is the last part of the data.
when MSG_EOR is not set, the msg will be truncated as before.
Yes, that would be a safe behavior. Is SCTP doing this?
///jon
In the first case, we don't solve any compatibility issue, if that is
the purpose. The programmer still has to add code to get the current
behavior.
In the latter case we would be on the 100% safe side, although I have a
real hard time to see that this could be a real issue. Why would anybody
deliberately design an application for having messages truncated.
///jon
to indicate we don't want the truncating msg.
When the msg flag returns with no MSG_EOR, it means there's more data to read.
Thanks.
- Erin
Signed-off-by: Xin Long <lucien....@gmail.com>
---
net/tipc/socket.c | 30 +++++++++++++++++++++---------
1 file changed, 21 insertions(+), 9 deletions(-)
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 34a97ea36cc8..504e59838b8b 100644
--- a/net/tipc/socket.c
+++ b/net/tipc/socket.c
@@ -1880,6 +1880,7 @@ static int tipc_recvmsg(struct socket *sock, struct
msghdr *m,
bool connected = !tipc_sk_type_connectionless(sk);
struct tipc_sock *tsk = tipc_sk(sk);
int rc, err, hlen, dlen, copy;
+ struct tipc_skb_cb *skb_cb;
struct sk_buff_head xmitq;
struct tipc_msg *hdr;
struct sk_buff *skb;
@@ -1903,6 +1904,7 @@ static int tipc_recvmsg(struct socket *sock, struct
msghdr *m,
if (unlikely(rc))
goto exit;
skb = skb_peek(&sk->sk_receive_queue);
+ skb_cb = TIPC_SKB_CB(skb);
hdr = buf_msg(skb);
dlen = msg_data_sz(hdr);
hlen = msg_hdr_sz(hdr);
@@ -1922,18 +1924,27 @@ static int tipc_recvmsg(struct socket *sock, struct
msghdr *m,
/* Capture data if non-error msg, otherwise just set return value */
if (likely(!err)) {
- copy = min_t(int, dlen, buflen);
- if (unlikely(copy != dlen))
- m->msg_flags |= MSG_TRUNC;
- rc = skb_copy_datagram_msg(skb, hlen, m, copy);
+ int offset = skb_cb->bytes_read;
+
+ copy = min_t(int, dlen - offset, buflen);
+ rc = skb_copy_datagram_msg(skb, hlen + offset, m, copy);
+ if (unlikely(rc))
+ goto exit;
+ if (unlikely(offset + copy < dlen)) {
+ if (!(flags & MSG_PEEK))
+ skb_cb->bytes_read = offset + copy;
+ } else {
+ m->msg_flags |= MSG_EOR;
+ skb_cb->bytes_read = 0;
+ }
} else {
copy = 0;
rc = 0;
- if (err != TIPC_CONN_SHUTDOWN && connected && !m->msg_control)
+ if (err != TIPC_CONN_SHUTDOWN && connected && !m->msg_control) {
rc = -ECONNRESET;
+ goto exit;
+ }
}
- if (unlikely(rc))
- goto exit;
/* Mark message as group event if applicable */
if (unlikely(grp_evt)) {
@@ -1956,9 +1967,10 @@ static int tipc_recvmsg(struct socket *sock, struct
msghdr *m,
tipc_node_distr_xmit(sock_net(sk), &xmitq);
}
- tsk_advance_rx_queue(sk);
+ if (!skb_cb->bytes_read)
+ tsk_advance_rx_queue(sk);
- if (likely(!connected))
+ if (likely(!connected) || skb_cb->bytes_read)
goto exit;
/* Send connection flow control advertisement when applicable */
--
2.27.0
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