root/include/net/snmp.h

INCLUDED FROM

/*
 *
 *              SNMP MIB entries for the IP subsystem.
 *              
 *              Alan Cox <gw4pts@gw4pts.ampr.org>
 *
 *              We don't chose to implement SNMP in the kernel (this would
 *              be silly as SNMP is a pain in the backside in places). We do
 *              however need to collect the MIB statistics and export them
 *              out of /proc (eventually)
 *
 *              This program is free software; you can redistribute it and/or
 *              modify it under the terms of the GNU General Public License
 *              as published by the Free Software Foundation; either version
 *              2 of the License, or (at your option) any later version.
 *
 */
 
#ifndef _SNMP_H
#define _SNMP_H

#include <linux/cache.h>
#include <linux/snmp.h>
#include <linux/smp.h>

/*
 * Mibs are stored in array of unsigned long.
 */
/*
 * struct snmp_mib{}
 *  - list of entries for particular API (such as /proc/net/snmp)
 *  - name of entries.
 */
struct snmp_mib {
        char *name;
        int entry;
};

#define SNMP_MIB_ITEM(_name,_entry)     {       \
        .name = _name,                          \
        .entry = _entry,                        \
}

#define SNMP_MIB_SENTINEL {     \
        .name = NULL,           \
        .entry = 0,             \
}

/*
 * We use all unsigned longs. Linux will soon be so reliable that even 
 * these will rapidly get too small 8-). Seriously consider the IpInReceives 
 * count on the 20Gb/s + networks people expect in a few years time!
 */

/* 
 * The rule for padding: 
 * Best is power of two because then the right structure can be found by a 
 * simple shift. The structure should be always cache line aligned.
 * gcc needs n=alignto(cachelinesize, popcnt(sizeof(bla_mib))) shift/add 
 * instructions to emulate multiply in case it is not power-of-two. 
 * Currently n is always <=3 for all sizes so simple cache line alignment 
 * is enough. 
 * 
 * The best solution would be a global CPU local area , especially on 64 
 * and 128byte cacheline machine it makes a *lot* of sense -AK
 */ 

#define __SNMP_MIB_ALIGN__      ____cacheline_aligned

/* IPstats */
#define IPSTATS_MIB_MAX __IPSTATS_MIB_MAX
struct ipstats_mib {
        unsigned long   mibs[IPSTATS_MIB_MAX];
} __SNMP_MIB_ALIGN__;

/* ICMP */
#define ICMP_MIB_DUMMY  __ICMP_MIB_MAX
#define ICMP_MIB_MAX    (__ICMP_MIB_MAX + 1)

struct icmp_mib {
        unsigned long   mibs[ICMP_MIB_MAX];
} __SNMP_MIB_ALIGN__;

#define ICMPMSG_MIB_MAX __ICMPMSG_MIB_MAX
struct icmpmsg_mib {
        unsigned long   mibs[ICMPMSG_MIB_MAX];
} __SNMP_MIB_ALIGN__;

/* ICMP6 (IPv6-ICMP) */
#define ICMP6_MIB_MAX   __ICMP6_MIB_MAX
struct icmpv6_mib {
        unsigned long   mibs[ICMP6_MIB_MAX];
} __SNMP_MIB_ALIGN__;

#define ICMP6MSG_MIB_MAX  __ICMP6MSG_MIB_MAX
struct icmpv6msg_mib {
        unsigned long   mibs[ICMP6MSG_MIB_MAX];
} __SNMP_MIB_ALIGN__;


/* TCP */
#define TCP_MIB_MAX     __TCP_MIB_MAX
struct tcp_mib {
        unsigned long   mibs[TCP_MIB_MAX];
} __SNMP_MIB_ALIGN__;

/* UDP */
#define UDP_MIB_MAX     __UDP_MIB_MAX
struct udp_mib {
        unsigned long   mibs[UDP_MIB_MAX];
} __SNMP_MIB_ALIGN__;

/* Linux */
#define LINUX_MIB_MAX   __LINUX_MIB_MAX
struct linux_mib {
        unsigned long   mibs[LINUX_MIB_MAX];
};

/* Linux Xfrm */
#define LINUX_MIB_XFRMMAX       __LINUX_MIB_XFRMMAX
struct linux_xfrm_mib {
        unsigned long   mibs[LINUX_MIB_XFRMMAX];
};

/* 
 * FIXME: On x86 and some other CPUs the split into user and softirq parts
 * is not needed because addl $1,memory is atomic against interrupts (but 
 * atomic_inc would be overkill because of the lock cycles). Wants new 
 * nonlocked_atomic_inc() primitives -AK
 */ 
#define DEFINE_SNMP_STAT(type, name)    \
        __typeof__(type) *name[2]
#define DECLARE_SNMP_STAT(type, name)   \
        extern __typeof__(type) *name[2]

#define SNMP_STAT_BHPTR(name)   (name[0])
#define SNMP_STAT_USRPTR(name)  (name[1])

#define SNMP_INC_STATS_BH(mib, field)   \
        (per_cpu_ptr(mib[0], raw_smp_processor_id())->mibs[field]++)
#define SNMP_INC_STATS_USER(mib, field) \
        do { \
                per_cpu_ptr(mib[1], get_cpu())->mibs[field]++; \
                put_cpu(); \
        } while (0)
#define SNMP_INC_STATS(mib, field)      \
        do { \
                per_cpu_ptr(mib[!in_softirq()], get_cpu())->mibs[field]++; \
                put_cpu(); \
        } while (0)
#define SNMP_DEC_STATS(mib, field)      \
        do { \
                per_cpu_ptr(mib[!in_softirq()], get_cpu())->mibs[field]--; \
                put_cpu(); \
        } while (0)
#define SNMP_ADD_STATS_BH(mib, field, addend)   \
        (per_cpu_ptr(mib[0], raw_smp_processor_id())->mibs[field] += addend)
#define SNMP_ADD_STATS_USER(mib, field, addend)         \
        do { \
                per_cpu_ptr(mib[1], get_cpu())->mibs[field] += addend; \
                put_cpu(); \
        } while (0)

#endif