[DCCP]: Set TX Queue Length Bounds via Sysctl
Previously the transmit queue was unbounded.
This patch by Ian McDonald
* puts a limit on transmit queue length
and sends back EAGAIN if the buffer is full
* sets the TX queue length to a sensible default
* implements tx buffer sysctls for DCCP
Signed-off-by: Ian McDonald <ian.mcdonald@xxxxxxxxxxx>
Signed-off-by: Gerrit Renker <gerrit@xxxxxxxxxxxxxx>
---
Documentation/networking/dccp.txt | 4 ++++
include/linux/sysctl.h | 1 +
net/dccp/dccp.h | 1 +
net/dccp/proto.c | 10 ++++++++++
net/dccp/sysctl.c | 9 +++++++++
5 files changed, 25 insertions(+)
--- a/Documentation/networking/dccp.txt
+++ b/Documentation/networking/dccp.txt
@@ -104,6 +104,10 @@ rx_ccid = 2
seq_window = 100
The initial sequence window (sec. 7.5.2).
+tx_qlen = 5
+ The size of the transmit buffer in packets. A value of 0 corresponds
+ to an unbounded transmit buffer.
+
Notes
=====
--- a/include/linux/sysctl.h
+++ b/include/linux/sysctl.h
@@ -617,6 +617,7 @@ enum {
NET_DCCP_DEFAULT_REQ_RETRIES = 7,
NET_DCCP_DEFAULT_RETRIES1 = 8,
NET_DCCP_DEFAULT_RETRIES2 = 9,
+ NET_DCCP_DEFAULT_TX_QLEN = 10,
};
/* /proc/sys/net/ipx */
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -87,6 +87,7 @@ extern int sysctl_dccp_feat_tx_ccid;
extern int sysctl_dccp_feat_ack_ratio;
extern int sysctl_dccp_feat_send_ack_vector;
extern int sysctl_dccp_feat_send_ndp_count;
+extern int sysctl_dccp_tx_qlen;
/* is seq1 < seq2 ? */
static inline int before48(const u64 seq1, const u64 seq2)
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -52,6 +52,9 @@ struct inet_hashinfo __cacheline_aligned
EXPORT_SYMBOL_GPL(dccp_hashinfo);
+/* the maximum queue length for tx in packets. 0 is no limit */
+int sysctl_dccp_tx_qlen __read_mostly = 5;
+
void dccp_set_state(struct sock *sk, const int state)
{
const int oldstate = sk->sk_state;
@@ -645,6 +648,13 @@ int dccp_sendmsg(struct kiocb *iocb, str
return -EMSGSIZE;
lock_sock(sk);
+
+ if (sysctl_dccp_tx_qlen &&
+ (sk->sk_write_queue.qlen >= sysctl_dccp_tx_qlen)) {
+ rc = -EAGAIN;
+ goto out_release;
+ }
+
timeo = sock_sndtimeo(sk, noblock);
/*
--- a/net/dccp/sysctl.c
+++ b/net/dccp/sysctl.c
@@ -91,6 +91,15 @@ static struct ctl_table dccp_default_tab
.mode = 0644,
.proc_handler = proc_dointvec,
},
+ {
+ .ctl_name = NET_DCCP_DEFAULT_TX_QLEN,
+ .procname = "tx_qlen",
+ .data = &sysctl_dccp_tx_qlen,
+ .maxlen = sizeof(sysctl_dccp_tx_qlen),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+
{ .ctl_name = 0, }
};
-
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