/* * Copyright (c) 2012 Apple Inc. All rights reserved. * * @APPLE_OSREFERENCE_LICENSE_HEADER_START@ * * This file contains Original Code and/or Modifications of Original Code * as defined in and that are subject to the Apple Public Source License * Version 2.0 (the 'License'). You may not use this file except in * compliance with the License. The rights granted to you under the License * may not be used to create, or enable the creation or redistribution of, * unlawful or unlicensed copies of an Apple operating system, or to * circumvent, violate, or enable the circumvention or violation of, any * terms of an Apple operating system software license agreement. * * Please obtain a copy of the License at * http://www.opensource.apple.com/apsl/ and read it before using this file. * * The Original Code and all software distributed under the License are * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES, * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. * Please see the License for the specific language governing rights and * limitations under the License. * * @APPLE_OSREFERENCE_LICENSE_HEADER_END@ */ /* * Flow Control and Feedback Advisory * * Each mbuf that is being sent out through an interface is tagged with a * unique 32-bit ID which will help to identify all the packets that belong * to a particular flow at the interface layer. Packets carrying such ID * would need to be marked with PKTF_FLOW_ID. Normally, this ID is computed * by the module that generates the flow. There are 3 kinds of flow sources * that are currently recognized: * * a. INPCB (INET/INET6 Protocol Control Block). When a socket is * connected, the flow hash for the socket is computed and stored in * the PCB. Further transmissions on the socket will cause the hash * value to be carried within the mbuf as the flow ID. * * b. Interface. When an interface is attached, the flow hash for the * interface is computed and stored in the ifnet. This value is * normally ignored for most network drivers, except for those that * reside atop another driver, e.g. a virtual interface performing * encapsulation/encryption on the original packet and sending the * newly-generated packet to another interface. Such interface needs * to associate all generated packets with the interface flow hash * value as the flow ID. * * c. PF (Packet Filter). When a packet goes through PF and it is not * already associated with a flow ID, PF will compute a flow hash and * store it in the packet as flow ID. When the packet is associated * with a PF state, the state record will have the flow ID stored * within, in order to avoid recalculating the flow hash. Although PF * is capable of generating flow IDs, it does not participate in flow * advisory, and therefore packets whose IDs are computed by PF will * not have their PKTF_FLOW_ADV packet flag set. * * Activation of flow advisory mechanism is done by setting the PKTF_FLOW_ADV * packet flag; because a flow ID is required, the mechanism will not take * place unless PKTF_FLOW_ID is set as well. The packet must also carry one * of the flow source types FLOWSRC_{INPCB,IFNET} in order to identify where * the flow advisory notification should be delivered to. As noted above, * FLOWSRC_PF does not participate in this mechanism. * * The classq module configured on the interface is responsible for exerting * flow control to the upper layers. This occurs when the number of packets * queued for a flow reaches a limit. The module generating the flow will * cease transmission until further flow advisory notice, and the flow will * be inserted into the classq's flow control list. * * When packets are dequeued from the classq and the number of packets for * a flow goes below a limit, the classq will transfer its flow control list * to the global fadv_list. This will then trigger the flow advisory thread * to run, which will cause the flow source modules to be notified that data * can now be generated for those previously flow-controlled flows. */ #include <sys/param.h> #include <sys/systm.h> #include <sys/kernel.h> #include <sys/mcache.h> #include <sys/mbuf.h> #include <sys/proc_internal.h> #include <sys/socketvar.h> #include <kern/assert.h> #include <kern/thread.h> #include <kern/locks.h> #include <kern/zalloc.h> #include <netinet/in_pcb.h> #include <net/flowadv.h> /* Lock group and attribute for fadv_lock */ static lck_grp_t *fadv_lock_grp; static lck_grp_attr_t *fadv_lock_grp_attr; decl_lck_mtx_data(static, fadv_lock); /* protected by fadv_lock */ static STAILQ_HEAD(fadv_head, flowadv_fcentry) fadv_list; static thread_t fadv_thread = THREAD_NULL; static uint32_t fadv_active; static unsigned int fadv_zone_size; /* size of flowadv_fcentry */ static struct zone *fadv_zone; /* zone for flowadv_fcentry */ #define FADV_ZONE_MAX 32 /* maximum elements in zone */ #define FADV_ZONE_NAME "fadv_zone" /* zone name */ static int flowadv_thread_cont(int); static void flowadv_thread_func(void *, wait_result_t); void flowadv_init(void) { STAILQ_INIT(&fadv_list); /* Setup lock group and attribute for fadv_lock */ fadv_lock_grp_attr = lck_grp_attr_alloc_init(); fadv_lock_grp = lck_grp_alloc_init("fadv_lock", fadv_lock_grp_attr); lck_mtx_init(&fadv_lock, fadv_lock_grp, NULL); fadv_zone_size = P2ROUNDUP(sizeof (struct flowadv_fcentry), sizeof (u_int64_t)); fadv_zone = zinit(fadv_zone_size, FADV_ZONE_MAX * fadv_zone_size, 0, FADV_ZONE_NAME); if (fadv_zone == NULL) { panic("%s: failed allocating %s", __func__, FADV_ZONE_NAME); /* NOTREACHED */ } zone_change(fadv_zone, Z_EXPAND, TRUE); zone_change(fadv_zone, Z_CALLERACCT, FALSE); if (kernel_thread_start(flowadv_thread_func, NULL, &fadv_thread) != KERN_SUCCESS) { panic("%s: couldn't create flow event advisory thread", __func__); /* NOTREACHED */ } thread_deallocate(fadv_thread); } struct flowadv_fcentry * flowadv_alloc_entry(int how) { struct flowadv_fcentry *fce; fce = (how == M_WAITOK) ? zalloc(fadv_zone) : zalloc_noblock(fadv_zone); if (fce != NULL) bzero(fce, fadv_zone_size); return (fce); } void flowadv_free_entry(struct flowadv_fcentry *fce) { zfree(fadv_zone, fce); } void flowadv_add(struct flowadv_fclist *fcl) { if (STAILQ_EMPTY(fcl)) return; lck_mtx_lock_spin(&fadv_lock); STAILQ_CONCAT(&fadv_list, fcl); VERIFY(!STAILQ_EMPTY(&fadv_list)); if (!fadv_active && fadv_thread != THREAD_NULL) wakeup_one((caddr_t)&fadv_list); lck_mtx_unlock(&fadv_lock); } static int flowadv_thread_cont(int err) { #pragma unused(err) for (;;) { lck_mtx_assert(&fadv_lock, LCK_MTX_ASSERT_OWNED); while (STAILQ_EMPTY(&fadv_list)) { VERIFY(!fadv_active); (void) msleep0(&fadv_list, &fadv_lock, (PSOCK | PSPIN), "flowadv_cont", 0, flowadv_thread_cont); /* NOTREACHED */ } fadv_active = 1; for (;;) { struct flowadv_fcentry *fce; VERIFY(!STAILQ_EMPTY(&fadv_list)); fce = STAILQ_FIRST(&fadv_list); STAILQ_REMOVE(&fadv_list, fce, flowadv_fcentry, fce_link); STAILQ_NEXT(fce, fce_link) = NULL; lck_mtx_unlock(&fadv_lock); switch (fce->fce_flowsrc) { case FLOWSRC_INPCB: inp_flowadv(fce->fce_flowid); break; case FLOWSRC_IFNET: ifnet_flowadv(fce->fce_flowid); break; case FLOWSRC_PF: default: break; } flowadv_free_entry(fce); lck_mtx_lock_spin(&fadv_lock); /* if there's no pending request, we're done */ if (STAILQ_EMPTY(&fadv_list)) break; } fadv_active = 0; } } static void flowadv_thread_func(void *v, wait_result_t w) { #pragma unused(v, w) lck_mtx_lock(&fadv_lock); (void) msleep0(&fadv_list, &fadv_lock, (PSOCK | PSPIN), "flowadv", 0, flowadv_thread_cont); /* * msleep0() shouldn't have returned as PCATCH was not set; * therefore assert in this case. */ lck_mtx_unlock(&fadv_lock); VERIFY(0); }