dccp: Lockless integration of CCID congestion-control plugins
Based on Arnaldo's earlier patch, this patch integrates the standardised
CCID congestion control plugins (CCID-2 and CCID-3) of DCCP with dccp.ko:
* enables a faster connection path by eliminating the need to always go
through the CCID registration lock;
* updates the implementation to use only a single array whose size equals
the number of configured CCIDs instead of the maximum (256);
* since the CCIDs are now fixed array elements, synchronization is no
longer needed, simplifying use and implementation.
CCID-2 is suggested as minimum for a basic DCCP implementation (RFC 4340, 10);
CCID-3 is a standards-track CCID supported by RFC 4342 and RFC 5348.
Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/Kconfig b/net/dccp/Kconfig
index 7aa2a7a..ad6dffd 100644
--- a/net/dccp/Kconfig
+++ b/net/dccp/Kconfig
@@ -1,7 +1,6 @@
menuconfig IP_DCCP
tristate "The DCCP Protocol (EXPERIMENTAL)"
depends on INET && EXPERIMENTAL
- select IP_DCCP_CCID2
---help---
Datagram Congestion Control Protocol (RFC 4340)
@@ -25,9 +24,6 @@
def_tristate y if (IP_DCCP = y && INET_DIAG = y)
def_tristate m
-config IP_DCCP_ACKVEC
- bool
-
source "net/dccp/ccids/Kconfig"
menu "DCCP Kernel Hacking"
diff --git a/net/dccp/Makefile b/net/dccp/Makefile
index f4f8793..5ff2e7b 100644
--- a/net/dccp/Makefile
+++ b/net/dccp/Makefile
@@ -2,14 +2,19 @@
dccp-y := ccid.o feat.o input.o minisocks.o options.o output.o proto.o timer.o
+#
+# CCID algorithms to be used by dccp.ko
+#
+# CCID-2 is default (RFC 4340, p. 77) and has Ack Vectors as dependency
+dccp-y += ccids/ccid2.o ackvec.o
+dccp-$(CONFIG_IP_DCCP_CCID3) += ccids/ccid3.o
+
dccp_ipv4-y := ipv4.o
# build dccp_ipv6 as module whenever either IPv6 or DCCP is a module
obj-$(subst y,$(CONFIG_IP_DCCP),$(CONFIG_IPV6)) += dccp_ipv6.o
dccp_ipv6-y := ipv6.o
-dccp-$(CONFIG_IP_DCCP_ACKVEC) += ackvec.o
-
obj-$(CONFIG_INET_DCCP_DIAG) += dccp_diag.o
obj-$(CONFIG_NET_DCCPPROBE) += dccp_probe.o
diff --git a/net/dccp/ackvec.h b/net/dccp/ackvec.h
index 4ccee03..569a33a 100644
--- a/net/dccp/ackvec.h
+++ b/net/dccp/ackvec.h
@@ -84,7 +84,7 @@
struct sock;
struct sk_buff;
-#ifdef CONFIG_IP_DCCP_ACKVEC
+#ifndef ___OLD_INTERFACE_TO_BE_REMOVED___
extern int dccp_ackvec_init(void);
extern void dccp_ackvec_exit(void);
@@ -106,7 +106,7 @@
{
return av->av_vec_len;
}
-#else /* CONFIG_IP_DCCP_ACKVEC */
+#else /* ___OLD_INTERFACE_TO_BE_REMOVED___ */
static inline int dccp_ackvec_init(void)
{
return 0;
diff --git a/net/dccp/ccid.c b/net/dccp/ccid.c
index bcc643f..538d3b1 100644
--- a/net/dccp/ccid.c
+++ b/net/dccp/ccid.c
@@ -13,6 +13,70 @@
#include "ccid.h"
+static struct ccid_operations *ccids[] = {
+ &ccid2_ops,
+#ifdef CONFIG_IP_DCCP_CCID3
+ &ccid3_ops,
+#endif
+};
+
+static struct ccid_operations *ccid_by_number(const u8 id)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(ccids); i++)
+ if (ccids[i]->ccid_id == id)
+ return ccids[i];
+ return NULL;
+}
+
+/* check that up to @array_len members in @ccid_array are supported */
+bool ccid_support_check(u8 const *ccid_array, u8 array_len)
+{
+ while (array_len > 0)
+ if (ccid_by_number(ccid_array[--array_len]) == NULL)
+ return false;
+ return true;
+}
+
+/**
+ * ccid_get_builtin_ccids - Populate a list of built-in CCIDs
+ * @ccid_array: pointer to copy into
+ * @array_len: value to return length into
+ * This function allocates memory - caller must see that it is freed after use.
+ */
+int ccid_get_builtin_ccids(u8 **ccid_array, u8 *array_len)
+{
+ *ccid_array = kmalloc(ARRAY_SIZE(ccids), gfp_any());
+ if (*ccid_array == NULL)
+ return -ENOBUFS;
+
+ for (*array_len = 0; *array_len < ARRAY_SIZE(ccids); *array_len += 1)
+ (*ccid_array)[*array_len] = ccids[*array_len]->ccid_id;
+ return 0;
+}
+
+int ccid_getsockopt_builtin_ccids(struct sock *sk, int len,
+ char __user *optval, int __user *optlen)
+{
+ u8 *ccid_array, array_len;
+ int err = 0;
+
+ if (len < ARRAY_SIZE(ccids))
+ return -EINVAL;
+
+ if (ccid_get_builtin_ccids(&ccid_array, &array_len))
+ return -ENOBUFS;
+
+ if (put_user(array_len, optlen) ||
+ copy_to_user(optval, ccid_array, array_len))
+ err = -EFAULT;
+
+ kfree(ccid_array);
+ return err;
+}
+
+#ifdef ___OLD_INTERFACE_TO_BE_REMOVED___
static u8 builtin_ccids[] = {
DCCPC_CCID2, /* CCID2 is supported by default */
#if defined(CONFIG_IP_DCCP_CCID3) || defined(CONFIG_IP_DCCP_CCID3_MODULE)
@@ -62,6 +126,7 @@
#define ccids_read_lock() do { } while(0)
#define ccids_read_unlock() do { } while(0)
#endif
+#endif /* ___OLD_INTERFACE_TO_BE_REMOVED___ */
static struct kmem_cache *ccid_kmem_cache_create(int obj_size, const char *fmt,...)
{
@@ -93,6 +158,7 @@
}
}
+#ifdef ___OLD_INTERFACE_TO_BE_REMOVED___
/* check that up to @array_len members in @ccid_array are supported */
bool ccid_support_check(u8 const *ccid_array, u8 array_len)
{
@@ -133,8 +199,9 @@
return -EFAULT;
return 0;
}
+#endif /* ___OLD_INTERFACE_TO_BE_REMOVED___ */
-int ccid_register(struct ccid_operations *ccid_ops)
+static int ccid_activate(struct ccid_operations *ccid_ops)
{
int err = -ENOBUFS;
@@ -152,79 +219,40 @@
if (ccid_ops->ccid_hc_tx_slab == NULL)
goto out_free_rx_slab;
- ccids_write_lock();
- err = -EEXIST;
- if (ccids[ccid_ops->ccid_id] == NULL) {
- ccids[ccid_ops->ccid_id] = ccid_ops;
- err = 0;
- }
- ccids_write_unlock();
- if (err != 0)
- goto out_free_tx_slab;
-
- pr_info("CCID: Registered CCID %d (%s)\n",
+ pr_info("CCID: Activated CCID %d (%s)\n",
ccid_ops->ccid_id, ccid_ops->ccid_name);
+ err = 0;
out:
return err;
-out_free_tx_slab:
- ccid_kmem_cache_destroy(ccid_ops->ccid_hc_tx_slab);
- ccid_ops->ccid_hc_tx_slab = NULL;
- goto out;
out_free_rx_slab:
ccid_kmem_cache_destroy(ccid_ops->ccid_hc_rx_slab);
ccid_ops->ccid_hc_rx_slab = NULL;
goto out;
}
-EXPORT_SYMBOL_GPL(ccid_register);
-
-int ccid_unregister(struct ccid_operations *ccid_ops)
+static void ccid_deactivate(struct ccid_operations *ccid_ops)
{
- ccids_write_lock();
- ccids[ccid_ops->ccid_id] = NULL;
- ccids_write_unlock();
-
ccid_kmem_cache_destroy(ccid_ops->ccid_hc_tx_slab);
ccid_ops->ccid_hc_tx_slab = NULL;
ccid_kmem_cache_destroy(ccid_ops->ccid_hc_rx_slab);
ccid_ops->ccid_hc_rx_slab = NULL;
- pr_info("CCID: Unregistered CCID %d (%s)\n",
+ pr_info("CCID: Deactivated CCID %d (%s)\n",
ccid_ops->ccid_id, ccid_ops->ccid_name);
- return 0;
}
-EXPORT_SYMBOL_GPL(ccid_unregister);
-
struct ccid *ccid_new(unsigned char id, struct sock *sk, int rx, gfp_t gfp)
{
- struct ccid_operations *ccid_ops;
+ struct ccid_operations *ccid_ops = ccid_by_number(id);
struct ccid *ccid = NULL;
- ccids_read_lock();
-#ifdef CONFIG_MODULES
- if (ccids[id] == NULL) {
- /* We only try to load if in process context */
- ccids_read_unlock();
- if (gfp & GFP_ATOMIC)
- goto out;
- request_module("net-dccp-ccid-%d", id);
- ccids_read_lock();
- }
-#endif
- ccid_ops = ccids[id];
if (ccid_ops == NULL)
- goto out_unlock;
-
- if (!try_module_get(ccid_ops->ccid_owner))
- goto out_unlock;
-
- ccids_read_unlock();
+ goto out;
ccid = kmem_cache_alloc(rx ? ccid_ops->ccid_hc_rx_slab :
ccid_ops->ccid_hc_tx_slab, gfp);
if (ccid == NULL)
- goto out_module_put;
+ goto out;
ccid->ccid_ops = ccid_ops;
if (rx) {
memset(ccid + 1, 0, ccid_ops->ccid_hc_rx_obj_size);
@@ -239,15 +267,10 @@
}
out:
return ccid;
-out_unlock:
- ccids_read_unlock();
- goto out;
out_free_ccid:
kmem_cache_free(rx ? ccid_ops->ccid_hc_rx_slab :
ccid_ops->ccid_hc_tx_slab, ccid);
ccid = NULL;
-out_module_put:
- module_put(ccid_ops->ccid_owner);
goto out;
}
@@ -270,10 +293,6 @@
ccid_ops->ccid_hc_tx_exit(sk);
kmem_cache_free(ccid_ops->ccid_hc_tx_slab, ccid);
}
- ccids_read_lock();
- if (ccids[ccid_ops->ccid_id] != NULL)
- module_put(ccid_ops->ccid_owner);
- ccids_read_unlock();
}
void ccid_hc_rx_delete(struct ccid *ccid, struct sock *sk)
@@ -289,3 +308,28 @@
}
EXPORT_SYMBOL_GPL(ccid_hc_tx_delete);
+
+int __init ccid_initialize_builtins(void)
+{
+ int i, err;
+
+ for (i = 0; i < ARRAY_SIZE(ccids); i++) {
+ err = ccid_activate(ccids[i]);
+ if (err)
+ goto unwind_registrations;
+ }
+ return 0;
+
+unwind_registrations:
+ while(--i >= 0)
+ ccid_deactivate(ccids[i]);
+ return err;
+}
+
+void ccid_cleanup_builtins(void)
+{
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(ccids); i++)
+ ccid_deactivate(ccids[i]);
+}
diff --git a/net/dccp/ccid.h b/net/dccp/ccid.h
index 18f6942..75c21c5 100644
--- a/net/dccp/ccid.h
+++ b/net/dccp/ccid.h
@@ -29,7 +29,6 @@
* @ccid_id: numerical CCID ID (up to %CCID_MAX, cf. table 5 in RFC 4340, 10.)
* @ccid_ccmps: the CCMPS including network/transport headers (0 when disabled)
* @ccid_name: alphabetical identifier string for @ccid_id
- * @ccid_owner: module which implements/owns this CCID
* @ccid_hc_{r,t}x_slab: memory pool for the receiver/sender half-connection
* @ccid_hc_{r,t}x_obj_size: size of the receiver/sender half-connection socket
*
@@ -48,7 +47,6 @@
unsigned char ccid_id;
__u32 ccid_ccmps;
const char *ccid_name;
- struct module *ccid_owner;
struct kmem_cache *ccid_hc_rx_slab,
*ccid_hc_tx_slab;
__u32 ccid_hc_rx_obj_size,
@@ -90,8 +88,13 @@
int __user *optlen);
};
-extern int ccid_register(struct ccid_operations *ccid_ops);
-extern int ccid_unregister(struct ccid_operations *ccid_ops);
+extern struct ccid_operations ccid2_ops;
+#ifdef CONFIG_IP_DCCP_CCID3
+extern struct ccid_operations ccid3_ops;
+#endif
+
+extern int ccid_initialize_builtins(void);
+extern void ccid_cleanup_builtins(void);
struct ccid {
struct ccid_operations *ccid_ops;
diff --git a/net/dccp/ccids/Kconfig b/net/dccp/ccids/Kconfig
index 1227594..b30f049 100644
--- a/net/dccp/ccids/Kconfig
+++ b/net/dccp/ccids/Kconfig
@@ -1,80 +1,52 @@
menu "DCCP CCIDs Configuration (EXPERIMENTAL)"
depends on EXPERIMENTAL
-config IP_DCCP_CCID2
- tristate "CCID2 (TCP-Like) (EXPERIMENTAL)"
- def_tristate IP_DCCP
- select IP_DCCP_ACKVEC
- ---help---
- CCID 2, TCP-like Congestion Control, denotes Additive Increase,
- Multiplicative Decrease (AIMD) congestion control with behavior
- modelled directly on TCP, including congestion window, slow start,
- timeouts, and so forth [RFC 2581]. CCID 2 achieves maximum
- bandwidth over the long term, consistent with the use of end-to-end
- congestion control, but halves its congestion window in response to
- each congestion event. This leads to the abrupt rate changes
- typical of TCP. Applications should use CCID 2 if they prefer
- maximum bandwidth utilization to steadiness of rate. This is often
- the case for applications that are not playing their data directly
- to the user. For example, a hypothetical application that
- transferred files over DCCP, using application-level retransmissions
- for lost packets, would prefer CCID 2 to CCID 3. On-line games may
- also prefer CCID 2. See RFC 4341 for further details.
-
- CCID2 is the default CCID used by DCCP.
-
config IP_DCCP_CCID2_DEBUG
- bool "CCID2 debugging messages"
- depends on IP_DCCP_CCID2
- ---help---
- Enable CCID2-specific debugging messages.
+ bool "CCID-2 debugging messages"
+ ---help---
+ Enable CCID-2 specific debugging messages.
- When compiling CCID2 as a module, this debugging output can
- additionally be toggled by setting the ccid2_debug module
- parameter to 0 or 1.
+ The debugging output can additionally be toggled by setting the
+ ccid2_debug parameter to 0 or 1.
- If in doubt, say N.
+ If in doubt, say N.
config IP_DCCP_CCID3
- tristate "CCID3 (TCP-Friendly) (EXPERIMENTAL)"
- def_tristate IP_DCCP
+ bool "CCID-3 (TCP-Friendly) (EXPERIMENTAL)"
+ def_bool y if (IP_DCCP = y || IP_DCCP = m)
select IP_DCCP_TFRC_LIB
---help---
- CCID 3 denotes TCP-Friendly Rate Control (TFRC), an equation-based
+ CCID-3 denotes TCP-Friendly Rate Control (TFRC), an equation-based
rate-controlled congestion control mechanism. TFRC is designed to
be reasonably fair when competing for bandwidth with TCP-like flows,
where a flow is "reasonably fair" if its sending rate is generally
within a factor of two of the sending rate of a TCP flow under the
same conditions. However, TFRC has a much lower variation of
- throughput over time compared with TCP, which makes CCID 3 more
- suitable than CCID 2 for applications such streaming media where a
+ throughput over time compared with TCP, which makes CCID-3 more
+ suitable than CCID-2 for applications such streaming media where a
relatively smooth sending rate is of importance.
- CCID 3 is further described in RFC 4342,
+ CCID-3 is further described in RFC 4342,
http://www.ietf.org/rfc/rfc4342.txt
The TFRC congestion control algorithms were initially described in
- RFC 3448.
+ RFC 5448.
This text was extracted from RFC 4340 (sec. 10.2),
http://www.ietf.org/rfc/rfc4340.txt
-
- To compile this CCID as a module, choose M here: the module will be
- called dccp_ccid3.
- If in doubt, say M.
+ If in doubt, say N.
config IP_DCCP_CCID3_DEBUG
- bool "CCID3 debugging messages"
- depends on IP_DCCP_CCID3
- ---help---
- Enable CCID3-specific debugging messages.
+ bool "CCID-3 debugging messages"
+ depends on IP_DCCP_CCID3
+ ---help---
+ Enable CCID-3 specific debugging messages.
- When compiling CCID3 as a module, this debugging output can
- additionally be toggled by setting the ccid3_debug module
- parameter to 0 or 1.
+ The debugging output can additionally be toggled by setting the
+ ccid3_debug parameter to 0 or 1.
- If in doubt, say N.
+ If in doubt, say N.
config IP_DCCP_CCID3_RTO
int "Use higher bound for nofeedback timer"
diff --git a/net/dccp/ccids/Makefile b/net/dccp/ccids/Makefile
index 438f20b..cdaefff 100644
--- a/net/dccp/ccids/Makefile
+++ b/net/dccp/ccids/Makefile
@@ -1,9 +1 @@
-obj-$(CONFIG_IP_DCCP_CCID3) += dccp_ccid3.o
-
-dccp_ccid3-y := ccid3.o
-
-obj-$(CONFIG_IP_DCCP_CCID2) += dccp_ccid2.o
-
-dccp_ccid2-y := ccid2.o
-
obj-y += lib/
diff --git a/net/dccp/ccids/ccid2.c b/net/dccp/ccids/ccid2.c
index c9ea19a..d235294 100644
--- a/net/dccp/ccids/ccid2.c
+++ b/net/dccp/ccids/ccid2.c
@@ -768,10 +768,9 @@
}
}
-static struct ccid_operations ccid2 = {
+struct ccid_operations ccid2_ops = {
.ccid_id = DCCPC_CCID2,
.ccid_name = "TCP-like",
- .ccid_owner = THIS_MODULE,
.ccid_hc_tx_obj_size = sizeof(struct ccid2_hc_tx_sock),
.ccid_hc_tx_init = ccid2_hc_tx_init,
.ccid_hc_tx_exit = ccid2_hc_tx_exit,
@@ -784,22 +783,5 @@
#ifdef CONFIG_IP_DCCP_CCID2_DEBUG
module_param(ccid2_debug, bool, 0644);
-MODULE_PARM_DESC(ccid2_debug, "Enable debug messages");
+MODULE_PARM_DESC(ccid2_debug, "Enable CCID-2 debug messages");
#endif
-
-static __init int ccid2_module_init(void)
-{
- return ccid_register(&ccid2);
-}
-module_init(ccid2_module_init);
-
-static __exit void ccid2_module_exit(void)
-{
- ccid_unregister(&ccid2);
-}
-module_exit(ccid2_module_exit);
-
-MODULE_AUTHOR("Andrea Bittau <a.bittau@cs.ucl.ac.uk>");
-MODULE_DESCRIPTION("DCCP TCP-Like (CCID2) CCID");
-MODULE_LICENSE("GPL");
-MODULE_ALIAS("net-dccp-ccid-2");
diff --git a/net/dccp/ccids/ccid3.c b/net/dccp/ccids/ccid3.c
index 3b8bd7c..a27b7f4 100644
--- a/net/dccp/ccids/ccid3.c
+++ b/net/dccp/ccids/ccid3.c
@@ -940,10 +940,9 @@
return 0;
}
-static struct ccid_operations ccid3 = {
+struct ccid_operations ccid3_ops = {
.ccid_id = DCCPC_CCID3,
.ccid_name = "TCP-Friendly Rate Control",
- .ccid_owner = THIS_MODULE,
.ccid_hc_tx_obj_size = sizeof(struct ccid3_hc_tx_sock),
.ccid_hc_tx_init = ccid3_hc_tx_init,
.ccid_hc_tx_exit = ccid3_hc_tx_exit,
@@ -964,23 +963,5 @@
#ifdef CONFIG_IP_DCCP_CCID3_DEBUG
module_param(ccid3_debug, bool, 0644);
-MODULE_PARM_DESC(ccid3_debug, "Enable debug messages");
+MODULE_PARM_DESC(ccid3_debug, "Enable CCID-3 debug messages");
#endif
-
-static __init int ccid3_module_init(void)
-{
- return ccid_register(&ccid3);
-}
-module_init(ccid3_module_init);
-
-static __exit void ccid3_module_exit(void)
-{
- ccid_unregister(&ccid3);
-}
-module_exit(ccid3_module_exit);
-
-MODULE_AUTHOR("Ian McDonald <ian.mcdonald@jandi.co.nz>, "
- "Arnaldo Carvalho de Melo <acme@ghostprotocols.net>");
-MODULE_DESCRIPTION("DCCP TFRC CCID3 CCID");
-MODULE_LICENSE("GPL");
-MODULE_ALIAS("net-dccp-ccid-3");
diff --git a/net/dccp/dccp.h b/net/dccp/dccp.h
index 0bc4c9a..f2230fc 100644
--- a/net/dccp/dccp.h
+++ b/net/dccp/dccp.h
@@ -432,10 +432,8 @@
{
const struct dccp_sock *dp = dccp_sk(sk);
return dp->dccps_timestamp_echo != 0 ||
-#ifdef CONFIG_IP_DCCP_ACKVEC
(dp->dccps_hc_rx_ackvec != NULL &&
dccp_ackvec_pending(dp->dccps_hc_rx_ackvec)) ||
-#endif
inet_csk_ack_scheduled(sk);
}
diff --git a/net/dccp/proto.c b/net/dccp/proto.c
index 1747cca..945b4d5 100644
--- a/net/dccp/proto.c
+++ b/net/dccp/proto.c
@@ -1118,9 +1118,15 @@
if (rc)
goto out_ackvec_exit;
+ rc = ccid_initialize_builtins();
+ if (rc)
+ goto out_sysctl_exit;
+
dccp_timestamping_init();
out:
return rc;
+out_sysctl_exit:
+ dccp_sysctl_exit();
out_ackvec_exit:
dccp_ackvec_exit();
out_free_dccp_mib:
@@ -1143,6 +1149,7 @@
static void __exit dccp_fini(void)
{
+ ccid_cleanup_builtins();
dccp_mib_exit();
free_pages((unsigned long)dccp_hashinfo.bhash,
get_order(dccp_hashinfo.bhash_size *