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authorTomasz Grobelny <tomasz@grobelny.oswiecenia.net>2010-12-04 12:38:01 (GMT)
committerGerrit Renker <gerrit@erg.abdn.ac.uk>2010-12-07 12:47:12 (GMT)
commit871a2c16c21b988688b4ab1a78eadd969765c0a3 (patch)
tree34ffb3be1402747ef3b7fdb754fb99778bd45728 /net/dccp/proto.c
parentcfa969e385a23e4c85f50e0ed5de25a2e18bf9d4 (diff)
downloadlinux-871a2c16c21b988688b4ab1a78eadd969765c0a3.tar.xz
dccp: Policy-based packet dequeueing infrastructure
This patch adds a generic infrastructure for policy-based dequeueing of TX packets and provides two policies: * a simple FIFO policy (which is the default) and * a priority based policy (set via socket options). Both policies honour the tx_qlen sysctl for the maximum size of the write queue (can be overridden via socket options). The priority policy uses skb->priority internally to assign an u32 priority identifier, using the same ranking as SO_PRIORITY. The skb->priority field is set to 0 when the packet leaves DCCP. The priority is supplied as ancillary data using cmsg(3), the patch also provides the requisite parsing routines. Signed-off-by: Tomasz Grobelny <tomasz@grobelny.oswiecenia.net> Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Diffstat (limited to 'net/dccp/proto.c')
-rw-r--r--net/dccp/proto.c67
1 files changed, 64 insertions, 3 deletions
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index ef343d5..d6a2249 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -185,6 +185,7 @@ int dccp_init_sock(struct sock *sk, const __u8 ctl_sock_initialized)
dp->dccps_role = DCCP_ROLE_UNDEFINED;
dp->dccps_service = DCCP_SERVICE_CODE_IS_ABSENT;
dp->dccps_l_ack_ratio = dp->dccps_r_ack_ratio = 1;
+ dp->dccps_tx_qlen = sysctl_dccp_tx_qlen;
dccp_init_xmit_timers(sk);
@@ -532,6 +533,20 @@ static int do_dccp_setsockopt(struct sock *sk, int level, int optname,
case DCCP_SOCKOPT_RECV_CSCOV:
err = dccp_setsockopt_cscov(sk, val, true);
break;
+ case DCCP_SOCKOPT_QPOLICY_ID:
+ if (sk->sk_state != DCCP_CLOSED)
+ err = -EISCONN;
+ else if (val < 0 || val >= DCCPQ_POLICY_MAX)
+ err = -EINVAL;
+ else
+ dp->dccps_qpolicy = val;
+ break;
+ case DCCP_SOCKOPT_QPOLICY_TXQLEN:
+ if (val < 0)
+ err = -EINVAL;
+ else
+ dp->dccps_tx_qlen = val;
+ break;
default:
err = -ENOPROTOOPT;
break;
@@ -639,6 +654,12 @@ static int do_dccp_getsockopt(struct sock *sk, int level, int optname,
case DCCP_SOCKOPT_RECV_CSCOV:
val = dp->dccps_pcrlen;
break;
+ case DCCP_SOCKOPT_QPOLICY_ID:
+ val = dp->dccps_qpolicy;
+ break;
+ case DCCP_SOCKOPT_QPOLICY_TXQLEN:
+ val = dp->dccps_tx_qlen;
+ break;
case 128 ... 191:
return ccid_hc_rx_getsockopt(dp->dccps_hc_rx_ccid, sk, optname,
len, (u32 __user *)optval, optlen);
@@ -681,6 +702,43 @@ int compat_dccp_getsockopt(struct sock *sk, int level, int optname,
EXPORT_SYMBOL_GPL(compat_dccp_getsockopt);
#endif
+static int dccp_msghdr_parse(struct msghdr *msg, struct sk_buff *skb)
+{
+ struct cmsghdr *cmsg = CMSG_FIRSTHDR(msg);
+
+ /*
+ * Assign an (opaque) qpolicy priority value to skb->priority.
+ *
+ * We are overloading this skb field for use with the qpolicy subystem.
+ * The skb->priority is normally used for the SO_PRIORITY option, which
+ * is initialised from sk_priority. Since the assignment of sk_priority
+ * to skb->priority happens later (on layer 3), we overload this field
+ * for use with queueing priorities as long as the skb is on layer 4.
+ * The default priority value (if nothing is set) is 0.
+ */
+ skb->priority = 0;
+
+ for (; cmsg != NULL; cmsg = CMSG_NXTHDR(msg, cmsg)) {
+
+ if (!CMSG_OK(msg, cmsg))
+ return -EINVAL;
+
+ if (cmsg->cmsg_level != SOL_DCCP)
+ continue;
+
+ switch (cmsg->cmsg_type) {
+ case DCCP_SCM_PRIORITY:
+ if (cmsg->cmsg_len != CMSG_LEN(sizeof(__u32)))
+ return -EINVAL;
+ skb->priority = *(__u32 *)CMSG_DATA(cmsg);
+ break;
+ default:
+ return -EINVAL;
+ }
+ }
+ return 0;
+}
+
int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
size_t len)
{
@@ -696,8 +754,7 @@ int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
lock_sock(sk);
- if (sysctl_dccp_tx_qlen &&
- (sk->sk_write_queue.qlen >= sysctl_dccp_tx_qlen)) {
+ if (dccp_qpolicy_full(sk)) {
rc = -EAGAIN;
goto out_release;
}
@@ -725,7 +782,11 @@ int dccp_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
if (rc != 0)
goto out_discard;
- skb_queue_tail(&sk->sk_write_queue, skb);
+ rc = dccp_msghdr_parse(msg, skb);
+ if (rc != 0)
+ goto out_discard;
+
+ dccp_qpolicy_push(sk, skb);
/*
* The xmit_timer is set if the TX CCID is rate-based and will expire
* when congestion control permits to release further packets into the