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) 2010-2011 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/11.0/sys/net/netisr.h 301270 2016-06-03 13:57:10Z bz $
   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_ARP      4               /* same as AF_LINK */
   56 #define NETISR_ETHER    5               /* ethernet input */
   57 #define NETISR_IPV6     6
   58 #define NETISR_NATM     7
   59 #define NETISR_EPAIR    8               /* if_epair(4) */
   60 #define NETISR_IP_DIRECT        9       /* direct-dispatch IPv4 */
   61 #define NETISR_IPV6_DIRECT      10      /* direct-dispatch IPv6 */
   62 
   63 /*
   64  * Protocol ordering and affinity policy constants.  See the detailed
   65  * discussion of policies later in the file.
   66  */
   67 #define NETISR_POLICY_SOURCE    1       /* Maintain source ordering. */
   68 #define NETISR_POLICY_FLOW      2       /* Maintain flow ordering. */
   69 #define NETISR_POLICY_CPU       3       /* Protocol determines CPU placement. */
   70 
   71 /*
   72  * Protocol dispatch policy constants; selects whether and when direct
   73  * dispatch is permitted.
   74  */
   75 #define NETISR_DISPATCH_DEFAULT         0       /* Use global default. */
   76 #define NETISR_DISPATCH_DEFERRED        1       /* Always defer dispatch. */
   77 #define NETISR_DISPATCH_HYBRID          2       /* Allow hybrid dispatch. */
   78 #define NETISR_DISPATCH_DIRECT          3       /* Always direct dispatch. */
   79 
   80 /*
   81  * Monitoring data structures, exported by sysctl(2).
   82  *
   83  * Three sysctls are defined.  First, a per-protocol structure exported by
   84  * net.isr.proto.
   85  */
   86 #define NETISR_NAMEMAXLEN       32
   87 struct sysctl_netisr_proto {
   88         u_int   snp_version;                    /* Length of struct. */
   89         char    snp_name[NETISR_NAMEMAXLEN];    /* nh_name */
   90         u_int   snp_proto;                      /* nh_proto */
   91         u_int   snp_qlimit;                     /* nh_qlimit */
   92         u_int   snp_policy;                     /* nh_policy */
   93         u_int   snp_flags;                      /* Various flags. */
   94         u_int   snp_dispatch;                   /* Dispatch policy. */
   95         u_int   _snp_ispare[6];
   96 };
   97 
   98 /*
   99  * Flags for sysctl_netisr_proto.snp_flags.
  100  */
  101 #define NETISR_SNP_FLAGS_M2FLOW         0x00000001      /* nh_m2flow */
  102 #define NETISR_SNP_FLAGS_M2CPUID        0x00000002      /* nh_m2cpuid */
  103 #define NETISR_SNP_FLAGS_DRAINEDCPU     0x00000004      /* nh_drainedcpu */
  104 
  105 /*
  106  * Next, a structure per-workstream, with per-protocol data, exported as
  107  * net.isr.workstream.
  108  */
  109 struct sysctl_netisr_workstream {
  110         u_int   snws_version;                   /* Length of struct. */
  111         u_int   snws_flags;                     /* Various flags. */
  112         u_int   snws_wsid;                      /* Workstream ID. */
  113         u_int   snws_cpu;                       /* nws_cpu */
  114         u_int   _snws_ispare[12];
  115 };
  116 
  117 /*
  118  * Flags for sysctl_netisr_workstream.snws_flags
  119  */
  120 #define NETISR_SNWS_FLAGS_INTR          0x00000001      /* nws_intr_event */
  121 
  122 /*
  123  * Finally, a per-workstream-per-protocol structure, exported as
  124  * net.isr.work.
  125  */
  126 struct sysctl_netisr_work {
  127         u_int   snw_version;                    /* Length of struct. */
  128         u_int   snw_wsid;                       /* Workstream ID. */
  129         u_int   snw_proto;                      /* Protocol number. */
  130         u_int   snw_len;                        /* nw_len */
  131         u_int   snw_watermark;                  /* nw_watermark */
  132         u_int   _snw_ispare[3];
  133 
  134         uint64_t        snw_dispatched;         /* nw_dispatched */
  135         uint64_t        snw_hybrid_dispatched;  /* nw_hybrid_dispatched */
  136         uint64_t        snw_qdrops;             /* nw_qdrops */
  137         uint64_t        snw_queued;             /* nw_queued */
  138         uint64_t        snw_handled;            /* nw_handled */
  139 
  140         uint64_t        _snw_llspare[7];
  141 };
  142 
  143 #ifdef _KERNEL
  144 
  145 /*-
  146  * Protocols express ordering constraints and affinity preferences by
  147  * implementing one or neither of nh_m2flow and nh_m2cpuid, which are used by
  148  * netisr to determine which per-CPU workstream to assign mbufs to.
  149  *
  150  * The following policies may be used by protocols:
  151  *
  152  * NETISR_POLICY_SOURCE - netisr should maintain source ordering without
  153  *                        advice from the protocol.  netisr will ignore any
  154  *                        flow IDs present on the mbuf for the purposes of
  155  *                        work placement.
  156  *
  157  * NETISR_POLICY_FLOW - netisr should maintain flow ordering as defined by
  158  *                      the mbuf header flow ID field.  If the protocol
  159  *                      implements nh_m2flow, then netisr will query the
  160  *                      protocol in the event that the mbuf doesn't have a
  161  *                      flow ID, falling back on source ordering.
  162  *
  163  * NETISR_POLICY_CPU - netisr will delegate all work placement decisions to
  164  *                     the protocol, querying nh_m2cpuid for each packet.
  165  *
  166  * Protocols might make decisions about work placement based on an existing
  167  * calculated flow ID on the mbuf, such as one provided in hardware, the
  168  * receive interface pointed to by the mbuf (if any), the optional source
  169  * identifier passed at some dispatch points, or even parse packet headers to
  170  * calculate a flow.  Both protocol handlers may return a new mbuf pointer
  171  * for the chain, or NULL if the packet proves invalid or m_pullup() fails.
  172  *
  173  * XXXRW: If we eventually support dynamic reconfiguration, there should be
  174  * protocol handlers to notify them of CPU configuration changes so that they
  175  * can rebalance work.
  176  */
  177 struct mbuf;
  178 typedef void             netisr_handler_t(struct mbuf *m);
  179 typedef struct mbuf     *netisr_m2cpuid_t(struct mbuf *m, uintptr_t source,
  180                          u_int *cpuid);
  181 typedef struct mbuf     *netisr_m2flow_t(struct mbuf *m, uintptr_t source);
  182 typedef void             netisr_drainedcpu_t(u_int cpuid);
  183 
  184 #define NETISR_CPUID_NONE       ((u_int)-1)     /* No affinity returned. */
  185 
  186 /*
  187  * Data structure describing a protocol handler.
  188  */
  189 struct netisr_handler {
  190         const char      *nh_name;       /* Character string protocol name. */
  191         netisr_handler_t *nh_handler;   /* Protocol handler. */
  192         netisr_m2flow_t *nh_m2flow;     /* Query flow for untagged packet. */
  193         netisr_m2cpuid_t *nh_m2cpuid;   /* Query CPU to process mbuf on. */
  194         netisr_drainedcpu_t *nh_drainedcpu; /* Callback when drained a queue. */
  195         u_int            nh_proto;      /* Integer protocol ID. */
  196         u_int            nh_qlimit;     /* Maximum per-CPU queue depth. */
  197         u_int            nh_policy;     /* Work placement policy. */
  198         u_int            nh_dispatch;   /* Dispatch policy. */
  199         u_int            nh_ispare[4];  /* For future use. */
  200         void            *nh_pspare[4];  /* For future use. */
  201 };
  202 
  203 /*
  204  * Register, unregister, and other netisr handler management functions.
  205  */
  206 void    netisr_clearqdrops(const struct netisr_handler *nhp);
  207 void    netisr_getqdrops(const struct netisr_handler *nhp,
  208             u_int64_t *qdropsp);
  209 void    netisr_getqlimit(const struct netisr_handler *nhp, u_int *qlimitp);
  210 void    netisr_register(const struct netisr_handler *nhp);
  211 int     netisr_setqlimit(const struct netisr_handler *nhp, u_int qlimit);
  212 void    netisr_unregister(const struct netisr_handler *nhp);
  213 #ifdef VIMAGE
  214 void    netisr_register_vnet(const struct netisr_handler *nhp);
  215 void    netisr_unregister_vnet(const struct netisr_handler *nhp);
  216 #endif
  217 
  218 /*
  219  * Process a packet destined for a protocol, and attempt direct dispatch.
  220  * Supplemental source ordering information can be passed using the _src
  221  * variant.
  222  */
  223 int     netisr_dispatch(u_int proto, struct mbuf *m);
  224 int     netisr_dispatch_src(u_int proto, uintptr_t source, struct mbuf *m);
  225 int     netisr_queue(u_int proto, struct mbuf *m);
  226 int     netisr_queue_src(u_int proto, uintptr_t source, struct mbuf *m);
  227 
  228 /*
  229  * Provide a default implementation of "map an ID to a CPU ID".
  230  */
  231 u_int   netisr_default_flow2cpu(u_int flowid);
  232 
  233 /*
  234  * Utility routines to return the number of CPUs participting in netisr, and
  235  * to return a mapping from a number to a CPU ID that can be used with the
  236  * scheduler.
  237  */
  238 u_int   netisr_get_cpucount(void);
  239 u_int   netisr_get_cpuid(u_int cpunumber);
  240 
  241 /*
  242  * Interfaces between DEVICE_POLLING and netisr.
  243  */
  244 void    netisr_sched_poll(void);
  245 void    netisr_poll(void);
  246 void    netisr_pollmore(void);
  247 
  248 #endif /* !_KERNEL */
  249 #endif /* !_NET_NETISR_H_ */

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