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-------- Original message --------From: Xin Long <[email protected]> Date:
2021-06-30 20:21 (GMT-05:00) To: Jon Maloy <[email protected]>, Erin Shepherd
<[email protected]>, [email protected] Subject:
[tipc-discussion] [PATCHv2 net-next] tipc: keep the skb in rcv
queue until the whole data is read Currently, when userspace reads a datagram
with a buffer that issmaller than this datagram, the data will be truncated and
onlypart of it can be received by users. It doesn't seem right thatusers don't
know the datagram size and have to use a huge bufferto read it to avoid the
truncation.This patch to fix it by keeping the skb in rcv queue until thewhole
data is read by users. Only the last msg of the datagramwill be marked with
MSG_EOR, just as TCP/SCTP does.Note that this will work as above only when
MSG_EOR is set in theflags parameter of recvmsg(), so that it won't break any
old userapplications.v1->v2: - To enable this only when the flags with MSG_EOR
is passed into recvmsg() to fix the compatibility isssue as Erin
noticed.Signed-off-by: Xin Long <[email protected]>--- net/tipc/socket.c |
36 +++++++++++++++++++++++++++--------- 1 file changed, 27 insertions(+), 9
deletions(-)diff --git a/net/tipc/socket.c b/net/tipc/socket.cindex
34a97ea36cc8..9b0b311c7ec1 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 +1924,33 @@ 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_EOR) {+
if (!(flags & MSG_PEEK))+
skb_cb->bytes_read = offset + copy;+ } else {+
m->msg_flags |= MSG_TRUNC;+
skb_cb->bytes_read = 0;+ }+ } else {+
if (flags & MSG_EOR)+ 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 +1973,10 @@ 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 */-- 2.27.0Signed-off-by:
Jon Maloy
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