Commit ddebc973 authored by Gerrit Renker's avatar Gerrit Renker Committed by David S. Miller
Browse files

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: default avatarGerrit Renker <gerrit@erg.abdn.ac.uk>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6ea2fde1

net/dccp/Kconfig

+0 −4
Original line number Diff line number Diff line 
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 @@ config INET_DCCP_DIAG 
	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"

net/dccp/Makefile

+7 −2
Original line number Diff line number Diff line
@@ -2,14 +2,19 @@ obj-$(CONFIG_IP_DCCP) += dccp.o dccp_ipv4.o 


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

net/dccp/ackvec.h

+2 −2
Original line number Diff line number Diff line
@@ -84,7 +84,7 @@ struct dccp_ackvec_record { 
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 @@ static inline int dccp_ackvec_pending(const struct dccp_ackvec *av) 
{

	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;

net/dccp/ccid.c

+100 −56
Original line number Diff line number Diff line
@@ -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 @@ static inline void ccids_read_unlock(void) 
#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 @@ static void ccid_kmem_cache_destroy(struct kmem_cache *slab) 
	}

}



#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 @@ int ccid_getsockopt_builtin_ccids(struct sock *sk, int len, 
		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 @@ int ccid_register(struct ccid_operations *ccid_ops) 
	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 @@ struct ccid *ccid_new(unsigned char id, struct sock *sk, int rx, gfp_t gfp) 
	}

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 @@ static void ccid_delete(struct ccid *ccid, struct sock *sk, int rx) 
			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 @@ void ccid_hc_tx_delete(struct ccid *ccid, struct sock *sk) 
}



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]);

}

net/dccp/ccid.h

+7 −4
Original line number Diff line number Diff line
@@ -29,7 +29,6 @@ struct tcp_info; 
 *  @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 @@ struct ccid_operations { 
	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 @@ struct ccid_operations { 
						 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;

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