From ddebc973c56b51b4e5d84d606f0430d81b895d67 Mon Sep 17 00:00:00 2001 From: Gerrit Renker Date: Sun, 4 Jan 2009 21:42:53 -0800 Subject: 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 Signed-off-by: David S. Miller --- net/dccp/ccid.c | 156 ++++++++++++++++++++++++++++++++++++-------------------- 1 file changed, 100 insertions(+), 56 deletions(-) (limited to 'net/dccp/ccid.c') 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 @@ 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]); +} -- cgit v1.1