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/9.0/sys/net/netisr.h 222249 2011-05-24 12:34:19Z 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  * Protocol dispatch policy constants; selects whether and when direct
   75  * dispatch is permitted.
   76  */
   77 #define NETISR_DISPATCH_DEFAULT         0       /* Use global default. */
   78 #define NETISR_DISPATCH_DEFERRED        1       /* Always defer dispatch. */
   79 #define NETISR_DISPATCH_HYBRID          2       /* Allow hybrid dispatch. */
   80 #define NETISR_DISPATCH_DIRECT          3       /* Always direct dispatch. */
   81 
   82 /*
   83  * Monitoring data structures, exported by sysctl(2).
   84  *
   85  * Three sysctls are defined.  First, a per-protocol structure exported by
   86  * net.isr.proto.
   87  */
   88 #define NETISR_NAMEMAXLEN       32
   89 struct sysctl_netisr_proto {
   90         u_int   snp_version;                    /* Length of struct. */
   91         char    snp_name[NETISR_NAMEMAXLEN];    /* nh_name */
   92         u_int   snp_proto;                      /* nh_proto */
   93         u_int   snp_qlimit;                     /* nh_qlimit */
   94         u_int   snp_policy;                     /* nh_policy */
   95         u_int   snp_flags;                      /* Various flags. */
   96         u_int   snp_dispatch;                   /* Dispatch policy. */
   97         u_int   _snp_ispare[6];
   98 };
   99 
  100 /*
  101  * Flags for sysctl_netisr_proto.snp_flags.
  102  */
  103 #define NETISR_SNP_FLAGS_M2FLOW         0x00000001      /* nh_m2flow */
  104 #define NETISR_SNP_FLAGS_M2CPUID        0x00000002      /* nh_m2cpuid */
  105 #define NETISR_SNP_FLAGS_DRAINEDCPU     0x00000004      /* nh_drainedcpu */
  106 
  107 /*
  108  * Next, a structure per-workstream, with per-protocol data, exported as
  109  * net.isr.workstream.
  110  */
  111 struct sysctl_netisr_workstream {
  112         u_int   snws_version;                   /* Length of struct. */
  113         u_int   snws_flags;                     /* Various flags. */
  114         u_int   snws_wsid;                      /* Workstream ID. */
  115         u_int   snws_cpu;                       /* nws_cpu */
  116         u_int   _snws_ispare[12];
  117 };
  118 
  119 /*
  120  * Flags for sysctl_netisr_workstream.snws_flags
  121  */
  122 #define NETISR_SNWS_FLAGS_INTR          0x00000001      /* nws_intr_event */
  123 
  124 /*
  125  * Finally, a per-workstream-per-protocol structure, exported as
  126  * net.isr.work.
  127  */
  128 struct sysctl_netisr_work {
  129         u_int   snw_version;                    /* Length of struct. */
  130         u_int   snw_wsid;                       /* Workstream ID. */
  131         u_int   snw_proto;                      /* Protocol number. */
  132         u_int   snw_len;                        /* nw_len */
  133         u_int   snw_watermark;                  /* nw_watermark */
  134         u_int   _snw_ispare[3];
  135 
  136         uint64_t        snw_dispatched;         /* nw_dispatched */
  137         uint64_t        snw_hybrid_dispatched;  /* nw_hybrid_dispatched */
  138         uint64_t        snw_qdrops;             /* nw_qdrops */
  139         uint64_t        snw_queued;             /* nw_queued */
  140         uint64_t        snw_handled;            /* nw_handled */
  141 
  142         uint64_t        _snw_llspare[7];
  143 };
  144 
  145 #ifdef _KERNEL
  146 
  147 /*-
  148  * Protocols express ordering constraints and affinity preferences by
  149  * implementing one or neither of nh_m2flow and nh_m2cpuid, which are used by
  150  * netisr to determine which per-CPU workstream to assign mbufs to.
  151  *
  152  * The following policies may be used by protocols:
  153  *
  154  * NETISR_POLICY_SOURCE - netisr should maintain source ordering without
  155  *                        advice from the protocol.  netisr will ignore any
  156  *                        flow IDs present on the mbuf for the purposes of
  157  *                        work placement.
  158  *
  159  * NETISR_POLICY_FLOW - netisr should maintain flow ordering as defined by
  160  *                      the mbuf header flow ID field.  If the protocol
  161  *                      implements nh_m2flow, then netisr will query the
  162  *                      protocol in the event that the mbuf doesn't have a
  163  *                      flow ID, falling back on source ordering.
  164  *
  165  * NETISR_POLICY_CPU - netisr will delegate all work placement decisions to
  166  *                     the protocol, querying nh_m2cpuid for each packet.
  167  *
  168  * Protocols might make decisions about work placement based on an existing
  169  * calculated flow ID on the mbuf, such as one provided in hardware, the
  170  * receive interface pointed to by the mbuf (if any), the optional source
  171  * identifier passed at some dispatch points, or even parse packet headers to
  172  * calculate a flow.  Both protocol handlers may return a new mbuf pointer
  173  * for the chain, or NULL if the packet proves invalid or m_pullup() fails.
  174  *
  175  * XXXRW: If we eventually support dynamic reconfiguration, there should be
  176  * protocol handlers to notify them of CPU configuration changes so that they
  177  * can rebalance work.
  178  */
  179 struct mbuf;
  180 typedef void             netisr_handler_t(struct mbuf *m);
  181 typedef struct mbuf     *netisr_m2cpuid_t(struct mbuf *m, uintptr_t source,
  182                          u_int *cpuid);
  183 typedef struct mbuf     *netisr_m2flow_t(struct mbuf *m, uintptr_t source);
  184 typedef void             netisr_drainedcpu_t(u_int cpuid);
  185 
  186 #define NETISR_CPUID_NONE       ((u_int)-1)     /* No affinity returned. */
  187 
  188 /*
  189  * Data structure describing a protocol handler.
  190  */
  191 struct netisr_handler {
  192         const char      *nh_name;       /* Character string protocol name. */
  193         netisr_handler_t *nh_handler;   /* Protocol handler. */
  194         netisr_m2flow_t *nh_m2flow;     /* Query flow for untagged packet. */
  195         netisr_m2cpuid_t *nh_m2cpuid;   /* Query CPU to process mbuf on. */
  196         netisr_drainedcpu_t *nh_drainedcpu; /* Callback when drained a queue. */
  197         u_int            nh_proto;      /* Integer protocol ID. */
  198         u_int            nh_qlimit;     /* Maximum per-CPU queue depth. */
  199         u_int            nh_policy;     /* Work placement policy. */
  200         u_int            nh_dispatch;   /* Dispatch policy. */
  201         u_int            nh_ispare[4];  /* For future use. */
  202         void            *nh_pspare[4];  /* For future use. */
  203 };
  204 
  205 /*
  206  * Register, unregister, and other netisr handler management functions.
  207  */
  208 void    netisr_clearqdrops(const struct netisr_handler *nhp);
  209 void    netisr_getqdrops(const struct netisr_handler *nhp,
  210             u_int64_t *qdropsp);
  211 void    netisr_getqlimit(const struct netisr_handler *nhp, u_int *qlimitp);
  212 void    netisr_register(const struct netisr_handler *nhp);
  213 int     netisr_setqlimit(const struct netisr_handler *nhp, u_int qlimit);
  214 void    netisr_unregister(const struct netisr_handler *nhp);
  215 
  216 /*
  217  * Process a packet destined for a protocol, and attempt direct dispatch.
  218  * Supplemental source ordering information can be passed using the _src
  219  * variant.
  220  */
  221 int     netisr_dispatch(u_int proto, struct mbuf *m);
  222 int     netisr_dispatch_src(u_int proto, uintptr_t source, struct mbuf *m);
  223 int     netisr_queue(u_int proto, struct mbuf *m);
  224 int     netisr_queue_src(u_int proto, uintptr_t source, struct mbuf *m);
  225 
  226 /*
  227  * Provide a default implementation of "map an ID to a CPU ID".
  228  */
  229 u_int   netisr_default_flow2cpu(u_int flowid);
  230 
  231 /*
  232  * Utility routines to return the number of CPUs participting in netisr, and
  233  * to return a mapping from a number to a CPU ID that can be used with the
  234  * scheduler.
  235  */
  236 u_int   netisr_get_cpucount(void);
  237 u_int   netisr_get_cpuid(u_int cpunumber);
  238 
  239 /*
  240  * Interfaces between DEVICE_POLLING and netisr.
  241  */
  242 void    netisr_sched_poll(void);
  243 void    netisr_poll(void);
  244 void    netisr_pollmore(void);
  245 
  246 #endif /* !_KERNEL */
  247 #endif /* !_NET_NETISR_H_ */

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