Re: [tipc-discussion] [PATCHv2 net-next] tipc: keep the skb in rcv queue until the whole data is read
On 7/5/21 11:57 PM, maloy wrote:
Sent from my Galaxy
Original message
From: Xin Long
Date: 2021-06-30 20:21 (GMT-05:00)
To: Jon Maloy , Erin Shepherd
, tipc-discussion@lists.sourceforge.net
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 is
smaller than this datagram, the data will be truncated and only
part of it can be received by users. It doesn't seem right that
users don't know the datagram size and have to use a huge buffer
to read it to avoid the truncation.
This patch to fix it by keeping the skb in rcv queue until the
whole data is read by users. Only the last msg of the datagram
will be marked with MSG_EOR, just as TCP/SCTP does.
Note that this will work as above only when MSG_EOR is set in the
flags parameter of recvmsg(), so that it won't break any old user
applications.
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
---
net/tipc/socket.c | 36 +++-
1 file changed, 27 insertions(+), 9 deletions(-)
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 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_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), );
}
- 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
Signed-off-by: Jon Maloy
Acked-by, of course ;-)
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Re: [tipc-discussion] [PATCHv2 net-next] tipc: keep the skb in rcv queue until the whole data is read
Sent from my Galaxy
Original message From: Xin Long Date:
2021-06-30 20:21 (GMT-05:00) To: Jon Maloy , Erin Shepherd
, tipc-discussion@lists.sourceforge.net 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 --- 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_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), ); } -
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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[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 is
smaller than this datagram, the data will be truncated and only
part of it can be received by users. It doesn't seem right that
users don't know the datagram size and have to use a huge buffer
to read it to avoid the truncation.
This patch to fix it by keeping the skb in rcv queue until the
whole data is read by users. Only the last msg of the datagram
will be marked with MSG_EOR, just as TCP/SCTP does.
Note that this will work as above only when MSG_EOR is set in the
flags parameter of recvmsg(), so that it won't break any old user
applications.
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
---
net/tipc/socket.c | 36 +++-
1 file changed, 27 insertions(+), 9 deletions(-)
diff --git a/net/tipc/socket.c b/net/tipc/socket.c
index 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_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), );
}
- 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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