freebsd-dev/sys/kern/subr_pcpu.c
Marko Zec 21ca7b57bd Change the curvnet variable from a global const struct vnet *,
previously always pointing to the default vnet context, to a
dynamically changing thread-local one.  The currvnet context
should be set on entry to networking code via CURVNET_SET() macros,
and reverted to previous state via CURVNET_RESTORE().  Recursions
on curvnet are permitted, though strongly discuouraged.

This change should have no functional impact on nooptions VIMAGE
kernel builds, where CURVNET_* macros expand to whitespace.

The curthread->td_vnet (aka curvnet) variable's purpose is to be an
indicator of the vnet context in which the current network-related
operation takes place, in case we cannot deduce the current vnet
context from any other source, such as by looking at mbuf's
m->m_pkthdr.rcvif->if_vnet, sockets's so->so_vnet etc.  Moreover, so
far curvnet has turned out to be an invaluable consistency checking
aid: it helps to catch cases when sockets, ifnets or any other
vnet-aware structures may have leaked from one vnet to another.

The exact placement of the CURVNET_SET() / CURVNET_RESTORE() macros
was a result of an empirical iterative process, whith an aim to
reduce recursions on CURVNET_SET() to a minimum, while still reducing
the scope of CURVNET_SET() to networking only operations - the
alternative would be calling CURVNET_SET() on each system call entry.
In general, curvnet has to be set in three typicall cases: when
processing socket-related requests from userspace or from within the
kernel; when processing inbound traffic flowing from device drivers
to upper layers of the networking stack, and when executing
timer-driven networking functions.

This change also introduces a DDB subcommand to show the list of all
vnet instances.

Approved by:	julian (mentor)
2009-05-05 10:56:12 +00:00

181 lines
4.8 KiB
C

/*-
* Copyright (c) 2001 Wind River Systems, Inc.
* All rights reserved.
* Written by: John Baldwin <jhb@FreeBSD.org>
*
* 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.
* 4. Neither the name of the author nor the names of any co-contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* 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.
*/
/*
* This module provides MI support for per-cpu data.
*
* Each architecture determines the mapping of logical CPU IDs to physical
* CPUs. The requirements of this mapping are as follows:
* - Logical CPU IDs must reside in the range 0 ... MAXCPU - 1.
* - The mapping is not required to be dense. That is, there may be
* gaps in the mappings.
* - The platform sets the value of MAXCPU in <machine/param.h>.
* - It is suggested, but not required, that in the non-SMP case, the
* platform define MAXCPU to be 1 and define the logical ID of the
* sole CPU as 0.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ddb.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/linker_set.h>
#include <sys/lock.h>
#include <sys/pcpu.h>
#include <sys/proc.h>
#include <sys/smp.h>
#include <ddb/ddb.h>
struct pcpu *cpuid_to_pcpu[MAXCPU];
struct cpuhead cpuhead = SLIST_HEAD_INITIALIZER(cpuhead);
/*
* Initialize the MI portions of a struct pcpu.
*/
void
pcpu_init(struct pcpu *pcpu, int cpuid, size_t size)
{
bzero(pcpu, size);
KASSERT(cpuid >= 0 && cpuid < MAXCPU,
("pcpu_init: invalid cpuid %d", cpuid));
pcpu->pc_cpuid = cpuid;
pcpu->pc_cpumask = 1 << cpuid;
cpuid_to_pcpu[cpuid] = pcpu;
SLIST_INSERT_HEAD(&cpuhead, pcpu, pc_allcpu);
cpu_pcpu_init(pcpu, cpuid, size);
pcpu->pc_rm_queue.rmq_next = &pcpu->pc_rm_queue;
pcpu->pc_rm_queue.rmq_prev = &pcpu->pc_rm_queue;
#ifdef KTR
snprintf(pcpu->pc_name, sizeof(pcpu->pc_name), "CPU %d", cpuid);
#endif
}
/*
* Destroy a struct pcpu.
*/
void
pcpu_destroy(struct pcpu *pcpu)
{
SLIST_REMOVE(&cpuhead, pcpu, pcpu, pc_allcpu);
cpuid_to_pcpu[pcpu->pc_cpuid] = NULL;
}
/*
* Locate a struct pcpu by cpu id.
*/
struct pcpu *
pcpu_find(u_int cpuid)
{
return (cpuid_to_pcpu[cpuid]);
}
#ifdef DDB
static void
show_pcpu(struct pcpu *pc)
{
struct thread *td;
db_printf("cpuid = %d\n", pc->pc_cpuid);
db_printf("curthread = ");
td = pc->pc_curthread;
if (td != NULL)
db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
td->td_name);
else
db_printf("none\n");
db_printf("curpcb = %p\n", pc->pc_curpcb);
db_printf("fpcurthread = ");
td = pc->pc_fpcurthread;
if (td != NULL)
db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
td->td_name);
else
db_printf("none\n");
db_printf("idlethread = ");
td = pc->pc_idlethread;
if (td != NULL)
db_printf("%p: pid %d \"%s\"\n", td, td->td_proc->p_pid,
td->td_name);
else
db_printf("none\n");
db_show_mdpcpu(pc);
#ifdef VIMAGE
db_printf("curvnet = %p\n", pc->pc_curthread->td_vnet);
#endif
#ifdef WITNESS
db_printf("spin locks held:\n");
witness_list_locks(&pc->pc_spinlocks);
#endif
}
DB_SHOW_COMMAND(pcpu, db_show_pcpu)
{
struct pcpu *pc;
int id;
if (have_addr)
id = ((addr >> 4) % 16) * 10 + (addr % 16);
else
id = PCPU_GET(cpuid);
pc = pcpu_find(id);
if (pc == NULL) {
db_printf("CPU %d not found\n", id);
return;
}
show_pcpu(pc);
}
DB_SHOW_ALL_COMMAND(pcpu, db_show_cpu_all)
{
struct pcpu *pc;
int id;
db_printf("Current CPU: %d\n\n", PCPU_GET(cpuid));
for (id = 0; id <= mp_maxid; id++) {
pc = pcpu_find(id);
if (pc != NULL) {
show_pcpu(pc);
db_printf("\n");
}
}
}
DB_SHOW_ALIAS(allpcpu, db_show_cpu_all);
#endif