FreeBSD/Linux Kernel Cross Reference
sys/net/netisr.h

     /*-
      * Copyright (c) 2007-2009 Robert N. M. Watson
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD: releng/8.0/sys/net/netisr.h 195892 2009-07-26 12:20:07Z bz $
     */
    
    #ifndef _NET_NETISR_H_
    #define _NET_NETISR_H_
    #ifdef _KERNEL
    
    /*
     * The netisr (network interrupt service routine) provides a deferred
     * execution evironment in which (generally inbound) network processing can
     * take place.  Protocols register handlers which will be executed directly,
     * or via deferred dispatch, depending on the circumstances.
     *
     * Historically, this was implemented by the BSD software ISR facility; it is
     * now implemented via a software ithread (SWI).
     */
    #define NETISR_IP       1
    #define NETISR_IGMP     2               /* IGMPv3 output queue */
    #define NETISR_ROUTE    3               /* routing socket */
    #define NETISR_AARP     4               /* Appletalk ARP */
    #define NETISR_ATALK2   5               /* Appletalk phase 2 */
    #define NETISR_ATALK1   6               /* Appletalk phase 1 */
    #define NETISR_ARP      7               /* same as AF_LINK */
    #define NETISR_IPX      8               /* same as AF_IPX */
    #define NETISR_ETHER    9               /* ethernet input */
    #define NETISR_IPV6     10
    #define NETISR_NATM     11
    #define NETISR_EPAIR    12              /* if_epair(4) */
    
    /*-
     * Protocols express ordering constraints and affinity preferences by
     * implementing one or neither of nh_m2flow and nh_m2cpuid, which are used by
     * netisr to determine which per-CPU workstream to assign mbufs to.
     *
     * The following policies may be used by protocols:
     *
     * NETISR_POLICY_SOURCE - netisr should maintain source ordering without
     *                        advice from the protocol.  netisr will ignore any
     *                        flow IDs present on the mbuf for the purposes of
     *                        work placement.
     *
     * NETISR_POLICY_FLOW - netisr should maintain flow ordering as defined by
     *                      the mbuf header flow ID field.  If the protocol
     *                      implements nh_m2flow, then netisr will query the
     *                      protocol in the event that the mbuf doesn't have a
     *                      flow ID, falling back on source ordering.
     *
     * NETISR_POLICY_CPU - netisr will delegate all work placement decisions to
     *                     the protocol, querying nh_m2cpuid for each packet.
     *
     * Protocols might make decisions about work placement based on an existing
     * calculated flow ID on the mbuf, such as one provided in hardware, the
     * receive interface pointed to by the mbuf (if any), the optional source
     * identifier passed at some dispatch points, or even parse packet headers to
     * calculate a flow.  Both protocol handlers may return a new mbuf pointer
     * for the chain, or NULL if the packet proves invalid or m_pullup() fails.
     *
     * XXXRW: If we eventually support dynamic reconfiguration, there should be
     * protocol handlers to notify them of CPU configuration changes so that they
     * can rebalance work.
     */
    struct mbuf;
    typedef void             netisr_handler_t (struct mbuf *m);
    typedef struct mbuf     *netisr_m2cpuid_t(struct mbuf *m, uintptr_t source,
                             u_int *cpuid);
    typedef struct mbuf     *netisr_m2flow_t(struct mbuf *m, uintptr_t source);
    typedef void             netisr_drainedcpu_t(u_int cpuid);
    
    #define NETISR_POLICY_SOURCE    1       /* Maintain source ordering. */
    #define NETISR_POLICY_FLOW      2       /* Maintain flow ordering. */
    #define NETISR_POLICY_CPU       3       /* Protocol determines CPU placement. */
    
    /*
     * Data structure describing a protocol handler.
    */
   struct netisr_handler {
           const char      *nh_name;       /* Character string protocol name. */
           netisr_handler_t *nh_handler;   /* Protocol handler. */
           netisr_m2flow_t *nh_m2flow;     /* Query flow for untagged packet. */
           netisr_m2cpuid_t *nh_m2cpuid;   /* Query CPU to process mbuf on. */
           netisr_drainedcpu_t *nh_drainedcpu; /* Callback when drained a queue. */
           u_int            nh_proto;      /* Integer protocol ID. */
           u_int            nh_qlimit;     /* Maximum per-CPU queue depth. */
           u_int            nh_policy;     /* Work placement policy. */
           u_int            nh_ispare[5];  /* For future use. */
           void            *nh_pspare[4];  /* For future use. */
   };
   
   /*
    * Register, unregister, and other netisr handler management functions.
    */
   void    netisr_clearqdrops(const struct netisr_handler *nhp);
   void    netisr_getqdrops(const struct netisr_handler *nhp,
               u_int64_t *qdropsp);
   void    netisr_getqlimit(const struct netisr_handler *nhp, u_int *qlimitp);
   void    netisr_register(const struct netisr_handler *nhp);
   int     netisr_setqlimit(const struct netisr_handler *nhp, u_int qlimit);
   void    netisr_unregister(const struct netisr_handler *nhp);
   
   /*
    * Process a packet destined for a protocol, and attempt direct dispatch.
    * Supplemental source ordering information can be passed using the _src
    * variant.
    */
   int     netisr_dispatch(u_int proto, struct mbuf *m);
   int     netisr_dispatch_src(u_int proto, uintptr_t source, struct mbuf *m);
   int     netisr_queue(u_int proto, struct mbuf *m);
   int     netisr_queue_src(u_int proto, uintptr_t source, struct mbuf *m);
   
   /*
    * Provide a default implementation of "map an ID to a CPU ID".
    */
   u_int   netisr_default_flow2cpu(u_int flowid);
   
   /*
    * Utility routines to return the number of CPUs participting in netisr, and
    * to return a mapping from a number to a CPU ID that can be used with the
    * scheduler.
    */
   u_int   netisr_get_cpucount(void);
   u_int   netisr_get_cpuid(u_int cpunumber);
   
   /*
    * Interfaces between DEVICE_POLLING and netisr.
    */
   void    netisr_sched_poll(void);
   void    netisr_poll(void);
   void    netisr_pollmore(void);
   
   #endif /* !_KERNEL */
   #endif /* !_NET_NETISR_H_ */

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