The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/net/netisr.h

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    1 /*-
    2  * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
    3  *
    4  * Copyright (c) 2007-2009 Robert N. M. Watson
    5  * Copyright (c) 2010-2011 Juniper Networks, Inc.
    6  * All rights reserved.
    7  *
    8  * This software was developed by Robert N. M. Watson under contract
    9  * to Juniper Networks, Inc.
   10  *
   11  * Redistribution and use in source and binary forms, with or without
   12  * modification, are permitted provided that the following conditions
   13  * are met:
   14  * 1. Redistributions of source code must retain the above copyright
   15  *    notice, this list of conditions and the following disclaimer.
   16  * 2. Redistributions in binary form must reproduce the above copyright
   17  *    notice, this list of conditions and the following disclaimer in the
   18  *    documentation and/or other materials provided with the distribution.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  * $FreeBSD$
   33  */
   34 
   35 #ifndef _NET_NETISR_H_
   36 #define _NET_NETISR_H_
   37 
   38 /*
   39  * The netisr (network interrupt service routine) provides a deferred
   40  * execution evironment in which (generally inbound) network processing can
   41  * take place.  Protocols register handlers which will be executed directly,
   42  * or via deferred dispatch, depending on the circumstances.
   43  *
   44  * Historically, this was implemented by the BSD software ISR facility; it is
   45  * now implemented via a software ithread (SWI).
   46  */
   47 
   48 /*
   49  * Protocol numbers, which are encoded in monitoring applications and kernel
   50  * modules.  Internally, these are used in bit shift operations so must have
   51  * a value 0 < proto < 32; we currently further limit at compile-time to 16
   52  * for array-sizing purposes.
   53  */
   54 #define NETISR_IP       1
   55 #define NETISR_IGMP     2               /* IGMPv3 output queue */
   56 #define NETISR_ROUTE    3               /* routing socket */
   57 #define NETISR_ARP      4               /* same as AF_LINK */
   58 #define NETISR_ETHER    5               /* ethernet input */
   59 #define NETISR_IPV6     6
   60 #define NETISR_EPAIR    8               /* if_epair(4) */
   61 #define NETISR_IP_DIRECT        9       /* direct-dispatch IPv4 */
   62 #define NETISR_IPV6_DIRECT      10      /* direct-dispatch IPv6 */
   63 
   64 /*
   65  * Protocol ordering and affinity policy constants.  See the detailed
   66  * discussion of policies later in the file.
   67  */
   68 #define NETISR_POLICY_SOURCE    1       /* Maintain source ordering. */
   69 #define NETISR_POLICY_FLOW      2       /* Maintain flow ordering. */
   70 #define NETISR_POLICY_CPU       3       /* Protocol determines CPU placement. */
   71 
   72 /*
   73  * Protocol dispatch policy constants; selects whether and when direct
   74  * dispatch is permitted.
   75  */
   76 #define NETISR_DISPATCH_DEFAULT         0       /* Use global default. */
   77 #define NETISR_DISPATCH_DEFERRED        1       /* Always defer dispatch. */
   78 #define NETISR_DISPATCH_HYBRID          2       /* Allow hybrid dispatch. */
   79 #define NETISR_DISPATCH_DIRECT          3       /* Always direct dispatch. */
   80 
   81 /*
   82  * Monitoring data structures, exported by sysctl(2).
   83  *
   84  * Three sysctls are defined.  First, a per-protocol structure exported by
   85  * net.isr.proto.
   86  */
   87 #define NETISR_NAMEMAXLEN       32
   88 struct sysctl_netisr_proto {
   89         u_int   snp_version;                    /* Length of struct. */
   90         char    snp_name[NETISR_NAMEMAXLEN];    /* nh_name */
   91         u_int   snp_proto;                      /* nh_proto */
   92         u_int   snp_qlimit;                     /* nh_qlimit */
   93         u_int   snp_policy;                     /* nh_policy */
   94         u_int   snp_flags;                      /* Various flags. */
   95         u_int   snp_dispatch;                   /* Dispatch policy. */
   96         u_int   _snp_ispare[6];
   97 };
   98 
   99 /*
  100  * Flags for sysctl_netisr_proto.snp_flags.
  101  */
  102 #define NETISR_SNP_FLAGS_M2FLOW         0x00000001      /* nh_m2flow */
  103 #define NETISR_SNP_FLAGS_M2CPUID        0x00000002      /* nh_m2cpuid */
  104 #define NETISR_SNP_FLAGS_DRAINEDCPU     0x00000004      /* nh_drainedcpu */
  105 
  106 /*
  107  * Next, a structure per-workstream, with per-protocol data, exported as
  108  * net.isr.workstream.
  109  */
  110 struct sysctl_netisr_workstream {
  111         u_int   snws_version;                   /* Length of struct. */
  112         u_int   snws_flags;                     /* Various flags. */
  113         u_int   snws_wsid;                      /* Workstream ID. */
  114         u_int   snws_cpu;                       /* nws_cpu */
  115         u_int   _snws_ispare[12];
  116 };
  117 
  118 /*
  119  * Flags for sysctl_netisr_workstream.snws_flags
  120  */
  121 #define NETISR_SNWS_FLAGS_INTR          0x00000001      /* nws_intr_event */
  122 
  123 /*
  124  * Finally, a per-workstream-per-protocol structure, exported as
  125  * net.isr.work.
  126  */
  127 struct sysctl_netisr_work {
  128         u_int   snw_version;                    /* Length of struct. */
  129         u_int   snw_wsid;                       /* Workstream ID. */
  130         u_int   snw_proto;                      /* Protocol number. */
  131         u_int   snw_len;                        /* nw_len */
  132         u_int   snw_watermark;                  /* nw_watermark */
  133         u_int   _snw_ispare[3];
  134 
  135         uint64_t        snw_dispatched;         /* nw_dispatched */
  136         uint64_t        snw_hybrid_dispatched;  /* nw_hybrid_dispatched */
  137         uint64_t        snw_qdrops;             /* nw_qdrops */
  138         uint64_t        snw_queued;             /* nw_queued */
  139         uint64_t        snw_handled;            /* nw_handled */
  140 
  141         uint64_t        _snw_llspare[7];
  142 };
  143 
  144 #ifdef _KERNEL
  145 
  146 /*-
  147  * Protocols express ordering constraints and affinity preferences by
  148  * implementing one or neither of nh_m2flow and nh_m2cpuid, which are used by
  149  * netisr to determine which per-CPU workstream to assign mbufs to.
  150  *
  151  * The following policies may be used by protocols:
  152  *
  153  * NETISR_POLICY_SOURCE - netisr should maintain source ordering without
  154  *                        advice from the protocol.  netisr will ignore any
  155  *                        flow IDs present on the mbuf for the purposes of
  156  *                        work placement.
  157  *
  158  * NETISR_POLICY_FLOW - netisr should maintain flow ordering as defined by
  159  *                      the mbuf header flow ID field.  If the protocol
  160  *                      implements nh_m2flow, then netisr will query the
  161  *                      protocol in the event that the mbuf doesn't have a
  162  *                      flow ID, falling back on source ordering.
  163  *
  164  * NETISR_POLICY_CPU - netisr will delegate all work placement decisions to
  165  *                     the protocol, querying nh_m2cpuid for each packet.
  166  *
  167  * Protocols might make decisions about work placement based on an existing
  168  * calculated flow ID on the mbuf, such as one provided in hardware, the
  169  * receive interface pointed to by the mbuf (if any), the optional source
  170  * identifier passed at some dispatch points, or even parse packet headers to
  171  * calculate a flow.  Both protocol handlers may return a new mbuf pointer
  172  * for the chain, or NULL if the packet proves invalid or m_pullup() fails.
  173  *
  174  * XXXRW: If we eventually support dynamic reconfiguration, there should be
  175  * protocol handlers to notify them of CPU configuration changes so that they
  176  * can rebalance work.
  177  */
  178 struct mbuf;
  179 typedef void             netisr_handler_t(struct mbuf *m);
  180 typedef struct mbuf     *netisr_m2cpuid_t(struct mbuf *m, uintptr_t source,
  181                          u_int *cpuid);
  182 typedef struct mbuf     *netisr_m2flow_t(struct mbuf *m, uintptr_t source);
  183 typedef void             netisr_drainedcpu_t(u_int cpuid);
  184 
  185 #define NETISR_CPUID_NONE       ((u_int)-1)     /* No affinity returned. */
  186 
  187 /*
  188  * Data structure describing a protocol handler.
  189  */
  190 struct netisr_handler {
  191         const char      *nh_name;       /* Character string protocol name. */
  192         netisr_handler_t *nh_handler;   /* Protocol handler. */
  193         netisr_m2flow_t *nh_m2flow;     /* Query flow for untagged packet. */
  194         netisr_m2cpuid_t *nh_m2cpuid;   /* Query CPU to process mbuf on. */
  195         netisr_drainedcpu_t *nh_drainedcpu; /* Callback when drained a queue. */
  196         u_int            nh_proto;      /* Integer protocol ID. */
  197         u_int            nh_qlimit;     /* Maximum per-CPU queue depth. */
  198         u_int            nh_policy;     /* Work placement policy. */
  199         u_int            nh_dispatch;   /* Dispatch policy. */
  200         u_int            nh_ispare[4];  /* For future use. */
  201         void            *nh_pspare[4];  /* For future use. */
  202 };
  203 
  204 /*
  205  * Register, unregister, and other netisr handler management functions.
  206  */
  207 void    netisr_clearqdrops(const struct netisr_handler *nhp);
  208 void    netisr_getqdrops(const struct netisr_handler *nhp,
  209             u_int64_t *qdropsp);
  210 void    netisr_getqlimit(const struct netisr_handler *nhp, u_int *qlimitp);
  211 void    netisr_register(const struct netisr_handler *nhp);
  212 int     netisr_setqlimit(const struct netisr_handler *nhp, u_int qlimit);
  213 void    netisr_unregister(const struct netisr_handler *nhp);
  214 #ifdef VIMAGE
  215 void    netisr_register_vnet(const struct netisr_handler *nhp);
  216 void    netisr_unregister_vnet(const struct netisr_handler *nhp);
  217 #endif
  218 
  219 /*
  220  * Process a packet destined for a protocol, and attempt direct dispatch.
  221  * Supplemental source ordering information can be passed using the _src
  222  * variant.
  223  */
  224 int     netisr_dispatch(u_int proto, struct mbuf *m);
  225 int     netisr_dispatch_src(u_int proto, uintptr_t source, struct mbuf *m);
  226 int     netisr_queue(u_int proto, struct mbuf *m);
  227 int     netisr_queue_src(u_int proto, uintptr_t source, struct mbuf *m);
  228 
  229 /*
  230  * Provide a default implementation of "map an ID to a CPU ID".
  231  */
  232 u_int   netisr_default_flow2cpu(u_int flowid);
  233 
  234 /*
  235  * Utility routines to return the number of CPUs participting in netisr, and
  236  * to return a mapping from a number to a CPU ID that can be used with the
  237  * scheduler.
  238  */
  239 u_int   netisr_get_cpucount(void);
  240 u_int   netisr_get_cpuid(u_int cpunumber);
  241 
  242 /*
  243  * Interfaces between DEVICE_POLLING and netisr.
  244  */
  245 void    netisr_sched_poll(void);
  246 void    netisr_poll(void);
  247 void    netisr_pollmore(void);
  248 
  249 #endif /* !_KERNEL */
  250 #endif /* !_NET_NETISR_H_ */

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