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linux/include/net/snmp.h
Tejun Heo 7d720c3e4f percpu: add __percpu sparse annotations to net 
Add __percpu sparse annotations to net.

These annotations are to make sparse consider percpu variables to be
in a different address space and warn if accessed without going
through percpu accessors.  This patch doesn't affect normal builds.

The macro and type tricks around snmp stats make things a bit
interesting.  DEFINE/DECLARE_SNMP_STAT() macros mark the target field
as __percpu and SNMP_UPD_PO_STATS() macro is updated accordingly.  All
snmp_mib_*() users which used to cast the argument to (void **) are
updated to cast it to (void __percpu **).

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: David S. Miller <davem@davemloft.net>
Cc: Patrick McHardy <kaber@trash.net>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Vlad Yasevich <vladislav.yasevich@hp.com>
Cc: netdev@vger.kernel.org
Signed-off-by: David S. Miller <davem@davemloft.net>
2010-02-16 23:05:38 -08:00

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/*
*
* 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 {
const 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) __percpu *name[2]
#define DECLARE_SNMP_STAT(type, name) \
extern __typeof__(type) __percpu *name[2]
#define SNMP_STAT_BHPTR(name) (name[0])
#define SNMP_STAT_USRPTR(name) (name[1])
#define SNMP_INC_STATS_BH(mib, field) \
__this_cpu_inc(mib[0]->mibs[field])
#define SNMP_INC_STATS_USER(mib, field) \
this_cpu_inc(mib[1]->mibs[field])
#define SNMP_INC_STATS(mib, field) \
this_cpu_inc(mib[!in_softirq()]->mibs[field])
#define SNMP_DEC_STATS(mib, field) \
this_cpu_dec(mib[!in_softirq()]->mibs[field])
#define SNMP_ADD_STATS_BH(mib, field, addend) \
__this_cpu_add(mib[0]->mibs[field], addend)
#define SNMP_ADD_STATS_USER(mib, field, addend) \
this_cpu_add(mib[1]->mibs[field], addend)
/*
* Use "__typeof__(*mib[0]) *ptr" instead of "__typeof__(mib[0]) ptr"
* to make @ptr a non-percpu pointer.
*/
#define SNMP_UPD_PO_STATS(mib, basefield, addend) \
do { \
__typeof__(*mib[0]) *ptr; \
preempt_disable(); \
ptr = this_cpu_ptr((mib)[!in_softirq()]); \
ptr->mibs[basefield##PKTS]++; \
ptr->mibs[basefield##OCTETS] += addend;\
preempt_enable(); \
} while (0)
#define SNMP_UPD_PO_STATS_BH(mib, basefield, addend) \
do { \
__typeof__(*mib[0]) *ptr = \
__this_cpu_ptr((mib)[!in_softirq()]); \
ptr->mibs[basefield##PKTS]++; \
ptr->mibs[basefield##OCTETS] += addend;\
} while (0)
#endif
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