The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: 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  * Copyright (c) 2007-2009 Robert N. M. Watson
    3  * Copyright (c) 2010 Juniper Networks, Inc.
    4  * All rights reserved.
    5  *
    6  * This software was developed by Robert N. M. Watson under contract
    7  * to Juniper Networks, Inc.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   28  * SUCH DAMAGE.
   29  *
   30  * $FreeBSD: releng/8.4/sys/net/netisr.h 217449 2011-01-15 19:02:08Z rwatson $
   31  */
   32 
   33 #ifndef _NET_NETISR_H_
   34 #define _NET_NETISR_H_
   35 
   36 /*
   37  * The netisr (network interrupt service routine) provides a deferred
   38  * execution evironment in which (generally inbound) network processing can
   39  * take place.  Protocols register handlers which will be executed directly,
   40  * or via deferred dispatch, depending on the circumstances.
   41  *
   42  * Historically, this was implemented by the BSD software ISR facility; it is
   43  * now implemented via a software ithread (SWI).
   44  */
   45 
   46 /*
   47  * Protocol numbers, which are encoded in monitoring applications and kernel
   48  * modules.  Internally, these are used in bit shift operations so must have
   49  * a value 0 < proto < 32; we currently further limit at compile-time to 16
   50  * for array-sizing purposes.
   51  */
   52 #define NETISR_IP       1
   53 #define NETISR_IGMP     2               /* IGMPv3 output queue */
   54 #define NETISR_ROUTE    3               /* routing socket */
   55 #define NETISR_AARP     4               /* Appletalk ARP */
   56 #define NETISR_ATALK2   5               /* Appletalk phase 2 */
   57 #define NETISR_ATALK1   6               /* Appletalk phase 1 */
   58 #define NETISR_ARP      7               /* same as AF_LINK */
   59 #define NETISR_IPX      8               /* same as AF_IPX */
   60 #define NETISR_ETHER    9               /* ethernet input */
   61 #define NETISR_IPV6     10
   62 #define NETISR_NATM     11
   63 #define NETISR_EPAIR    12              /* if_epair(4) */
   64 
   65 /*
   66  * Protocol ordering and affinity policy constants.  See the detailed
   67  * discussion of policies later in the file.
   68  */
   69 #define NETISR_POLICY_SOURCE    1       /* Maintain source ordering. */
   70 #define NETISR_POLICY_FLOW      2       /* Maintain flow ordering. */
   71 #define NETISR_POLICY_CPU       3       /* Protocol determines CPU placement. */
   72 
   73 /*
   74  * Monitoring data structures, exported by sysctl(2).
   75  *
   76  * Three sysctls are defined.  First, a per-protocol structure exported by
   77  * net.isr.proto.
   78  */
   79 #define NETISR_NAMEMAXLEN       32
   80 struct sysctl_netisr_proto {
   81         u_int   snp_version;                    /* Length of struct. */
   82         char    snp_name[NETISR_NAMEMAXLEN];    /* nh_name */
   83         u_int   snp_proto;                      /* nh_proto */
   84         u_int   snp_qlimit;                     /* nh_qlimit */
   85         u_int   snp_policy;                     /* nh_policy */
   86         u_int   snp_flags;                      /* Various flags. */
   87         u_int   _snp_ispare[7];
   88 };
   89 
   90 /*
   91  * Flags for sysctl_netisr_proto.snp_flags.
   92  */
   93 #define NETISR_SNP_FLAGS_M2FLOW         0x00000001      /* nh_m2flow */
   94 #define NETISR_SNP_FLAGS_M2CPUID        0x00000002      /* nh_m2cpuid */
   95 #define NETISR_SNP_FLAGS_DRAINEDCPU     0x00000004      /* nh_drainedcpu */
   96 
   97 /*
   98  * Next, a structure per-workstream, with per-protocol data, exported as
   99  * net.isr.workstream.
  100  */
  101 struct sysctl_netisr_workstream {
  102         u_int   snws_version;                   /* Length of struct. */
  103         u_int   snws_flags;                     /* Various flags. */
  104         u_int   snws_wsid;                      /* Workstream ID. */
  105         u_int   snws_cpu;                       /* nws_cpu */
  106         u_int   _snws_ispare[12];
  107 };
  108 
  109 /*
  110  * Flags for sysctl_netisr_workstream.snws_flags
  111  */
  112 #define NETISR_SNWS_FLAGS_INTR          0x00000001      /* nws_intr_event */
  113 
  114 /*
  115  * Finally, a per-workstream-per-protocol structure, exported as
  116  * net.isr.work.
  117  */
  118 struct sysctl_netisr_work {
  119         u_int   snw_version;                    /* Length of struct. */
  120         u_int   snw_wsid;                       /* Workstream ID. */
  121         u_int   snw_proto;                      /* Protocol number. */
  122         u_int   snw_len;                        /* nw_len */
  123         u_int   snw_watermark;                  /* nw_watermark */
  124         u_int   _snw_ispare[3];
  125 
  126         uint64_t        snw_dispatched;         /* nw_dispatched */
  127         uint64_t        snw_hybrid_dispatched;  /* nw_hybrid_dispatched */
  128         uint64_t        snw_qdrops;             /* nw_qdrops */
  129         uint64_t        snw_queued;             /* nw_queued */
  130         uint64_t        snw_handled;            /* nw_handled */
  131 
  132         uint64_t        _snw_llspare[7];
  133 };
  134 
  135 #ifdef _KERNEL
  136 
  137 /*-
  138  * Protocols express ordering constraints and affinity preferences by
  139  * implementing one or neither of nh_m2flow and nh_m2cpuid, which are used by
  140  * netisr to determine which per-CPU workstream to assign mbufs to.
  141  *
  142  * The following policies may be used by protocols:
  143  *
  144  * NETISR_POLICY_SOURCE - netisr should maintain source ordering without
  145  *                        advice from the protocol.  netisr will ignore any
  146  *                        flow IDs present on the mbuf for the purposes of
  147  *                        work placement.
  148  *
  149  * NETISR_POLICY_FLOW - netisr should maintain flow ordering as defined by
  150  *                      the mbuf header flow ID field.  If the protocol
  151  *                      implements nh_m2flow, then netisr will query the
  152  *                      protocol in the event that the mbuf doesn't have a
  153  *                      flow ID, falling back on source ordering.
  154  *
  155  * NETISR_POLICY_CPU - netisr will delegate all work placement decisions to
  156  *                     the protocol, querying nh_m2cpuid for each packet.
  157  *
  158  * Protocols might make decisions about work placement based on an existing
  159  * calculated flow ID on the mbuf, such as one provided in hardware, the
  160  * receive interface pointed to by the mbuf (if any), the optional source
  161  * identifier passed at some dispatch points, or even parse packet headers to
  162  * calculate a flow.  Both protocol handlers may return a new mbuf pointer
  163  * for the chain, or NULL if the packet proves invalid or m_pullup() fails.
  164  *
  165  * XXXRW: If we eventually support dynamic reconfiguration, there should be
  166  * protocol handlers to notify them of CPU configuration changes so that they
  167  * can rebalance work.
  168  */
  169 struct mbuf;
  170 typedef void             netisr_handler_t(struct mbuf *m);
  171 typedef struct mbuf     *netisr_m2cpuid_t(struct mbuf *m, uintptr_t source,
  172                          u_int *cpuid);
  173 typedef struct mbuf     *netisr_m2flow_t(struct mbuf *m, uintptr_t source);
  174 typedef void             netisr_drainedcpu_t(u_int cpuid);
  175 
  176 /*
  177  * Data structure describing a protocol handler.
  178  */
  179 struct netisr_handler {
  180         const char      *nh_name;       /* Character string protocol name. */
  181         netisr_handler_t *nh_handler;   /* Protocol handler. */
  182         netisr_m2flow_t *nh_m2flow;     /* Query flow for untagged packet. */
  183         netisr_m2cpuid_t *nh_m2cpuid;   /* Query CPU to process mbuf on. */
  184         netisr_drainedcpu_t *nh_drainedcpu; /* Callback when drained a queue. */
  185         u_int            nh_proto;      /* Integer protocol ID. */
  186         u_int            nh_qlimit;     /* Maximum per-CPU queue depth. */
  187         u_int            nh_policy;     /* Work placement policy. */
  188         u_int            nh_ispare[5];  /* For future use. */
  189         void            *nh_pspare[4];  /* For future use. */
  190 };
  191 
  192 /*
  193  * Register, unregister, and other netisr handler management functions.
  194  */
  195 void    netisr_clearqdrops(const struct netisr_handler *nhp);
  196 void    netisr_getqdrops(const struct netisr_handler *nhp,
  197             u_int64_t *qdropsp);
  198 void    netisr_getqlimit(const struct netisr_handler *nhp, u_int *qlimitp);
  199 void    netisr_register(const struct netisr_handler *nhp);
  200 int     netisr_setqlimit(const struct netisr_handler *nhp, u_int qlimit);
  201 void    netisr_unregister(const struct netisr_handler *nhp);
  202 
  203 /*
  204  * Process a packet destined for a protocol, and attempt direct dispatch.
  205  * Supplemental source ordering information can be passed using the _src
  206  * variant.
  207  */
  208 int     netisr_dispatch(u_int proto, struct mbuf *m);
  209 int     netisr_dispatch_src(u_int proto, uintptr_t source, struct mbuf *m);
  210 int     netisr_queue(u_int proto, struct mbuf *m);
  211 int     netisr_queue_src(u_int proto, uintptr_t source, struct mbuf *m);
  212 
  213 /*
  214  * Provide a default implementation of "map an ID to a CPU ID".
  215  */
  216 u_int   netisr_default_flow2cpu(u_int flowid);
  217 
  218 /*
  219  * Utility routines to return the number of CPUs participting in netisr, and
  220  * to return a mapping from a number to a CPU ID that can be used with the
  221  * scheduler.
  222  */
  223 u_int   netisr_get_cpucount(void);
  224 u_int   netisr_get_cpuid(u_int cpunumber);
  225 
  226 /*
  227  * Interfaces between DEVICE_POLLING and netisr.
  228  */
  229 void    netisr_sched_poll(void);
  230 void    netisr_poll(void);
  231 void    netisr_pollmore(void);
  232 
  233 #endif /* !_KERNEL */
  234 #endif /* !_NET_NETISR_H_ */

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