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f0796cd26c
opt_device_polling.h - Include opt_device_polling.h into appropriate files. - Embrace with HAVE_KERNEL_OPTION_HEADERS the include in the files that can be compiled as loadable modules. Reviewed by: bde
363 lines
10 KiB
C
363 lines
10 KiB
C
/*-
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* Copyright (c) 2001,2002,2003 Jonathan Lemon <jlemon@FreeBSD.org>
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* Copyright (c) 1997, Stefan Esser <se@freebsd.org>
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $FreeBSD$
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*/
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#include "opt_device_polling.h"
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#include "opt_net.h"
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#include <sys/param.h>
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#include <sys/bus.h>
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#include <sys/rtprio.h>
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#include <sys/systm.h>
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#include <sys/interrupt.h>
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#include <sys/kernel.h>
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#include <sys/kthread.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/proc.h>
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#include <sys/random.h>
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#include <sys/resourcevar.h>
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#include <sys/sysctl.h>
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#include <sys/unistd.h>
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#include <machine/atomic.h>
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#include <machine/cpu.h>
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#include <machine/stdarg.h>
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#include <sys/mbuf.h>
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#include <sys/socket.h>
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#include <net/if.h>
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#include <net/if_types.h>
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#include <net/if_var.h>
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#include <net/netisr.h>
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/*
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* debug_mpsafenet controls network subsystem-wide use of the Giant lock,
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* from system calls down to interrupt handlers. It can be changed only via
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* a tunable at boot, not at run-time, due to the complexity of unwinding.
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* The compiled default is set via a kernel option; right now, the default
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* unless otherwise specified is to run the network stack without Giant.
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*/
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#ifdef NET_WITH_GIANT
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int debug_mpsafenet = 0;
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#else
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int debug_mpsafenet = 1;
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#endif
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int debug_mpsafenet_toolatetotwiddle = 0;
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TUNABLE_INT("debug.mpsafenet", &debug_mpsafenet);
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SYSCTL_INT(_debug, OID_AUTO, mpsafenet, CTLFLAG_RD, &debug_mpsafenet, 0,
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"Enable/disable MPSAFE network support");
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volatile unsigned int netisr; /* scheduling bits for network */
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struct netisr {
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netisr_t *ni_handler;
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struct ifqueue *ni_queue;
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int ni_flags;
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} netisrs[32];
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static void *net_ih;
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/*
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* Not all network code is currently capable of running MPSAFE; however,
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* most of it is. Since those sections that are not are generally optional
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* components not shipped with default kernels, we provide a basic way to
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* determine whether MPSAFE operation is permitted: based on a default of
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* yes, we permit non-MPSAFE components to use a registration call to
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* identify that they require Giant. If the system is early in the boot
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* process still, then we change the debug_mpsafenet setting to choose a
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* non-MPSAFE execution mode (degraded). If it's too late for that (since
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* the setting cannot be changed at run time), we generate a console warning
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* that the configuration may be unsafe.
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*/
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static int mpsafe_warn_count;
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/*
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* Function call implementing registration of a non-MPSAFE network component.
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*/
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void
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net_warn_not_mpsafe(const char *component)
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{
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/*
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* If we're running with Giant over the network stack, there is no
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* problem.
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*/
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if (!debug_mpsafenet)
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return;
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/*
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* If it's not too late to change the MPSAFE setting for the network
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* stack, do so now. This effectively suppresses warnings by
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* components registering later.
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*/
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if (!debug_mpsafenet_toolatetotwiddle) {
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debug_mpsafenet = 0;
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printf("WARNING: debug.mpsafenet forced to 0 as %s requires "
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"Giant\n", component);
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return;
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}
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/*
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* We must run without Giant, so generate a console warning with some
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* information with what to do about it. The system may be operating
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* unsafely, however.
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*/
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printf("WARNING: Network stack Giant-free, but %s requires Giant.\n",
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component);
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if (mpsafe_warn_count == 0)
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printf(" Consider adding 'options NET_WITH_GIANT' or "
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"setting debug.mpsafenet=0\n");
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mpsafe_warn_count++;
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}
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/*
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* This sysinit is run after any pre-loaded or compiled-in components have
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* announced that they require Giant, but before any modules loaded at
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* run-time.
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*/
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static void
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net_mpsafe_toolate(void *arg)
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{
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debug_mpsafenet_toolatetotwiddle = 1;
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if (!debug_mpsafenet)
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printf("WARNING: MPSAFE network stack disabled, expect "
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"reduced performance.\n");
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}
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SYSINIT(net_mpsafe_toolate, SI_SUB_SETTINGS, SI_ORDER_ANY, net_mpsafe_toolate,
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NULL);
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void
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legacy_setsoftnet(void)
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{
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swi_sched(net_ih, 0);
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}
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void
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netisr_register(int num, netisr_t *handler, struct ifqueue *inq, int flags)
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{
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KASSERT(!(num < 0 || num >= (sizeof(netisrs)/sizeof(*netisrs))),
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("bad isr %d", num));
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netisrs[num].ni_handler = handler;
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netisrs[num].ni_queue = inq;
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if ((flags & NETISR_MPSAFE) && !debug_mpsafenet)
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flags &= ~NETISR_MPSAFE;
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netisrs[num].ni_flags = flags;
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}
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void
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netisr_unregister(int num)
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{
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struct netisr *ni;
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KASSERT(!(num < 0 || num >= (sizeof(netisrs)/sizeof(*netisrs))),
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("bad isr %d", num));
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ni = &netisrs[num];
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ni->ni_handler = NULL;
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if (ni->ni_queue != NULL)
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IF_DRAIN(ni->ni_queue);
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ni->ni_queue = NULL;
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}
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struct isrstat {
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int isrs_count; /* dispatch count */
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int isrs_directed; /* ...directly dispatched */
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int isrs_deferred; /* ...queued instead */
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int isrs_queued; /* intentionally queueued */
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int isrs_drop; /* dropped 'cuz no handler */
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int isrs_swi_count; /* swi_net handlers called */
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};
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static struct isrstat isrstat;
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SYSCTL_NODE(_net, OID_AUTO, isr, CTLFLAG_RW, 0, "netisr counters");
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static int netisr_direct = 0;
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SYSCTL_INT(_net_isr, OID_AUTO, direct, CTLFLAG_RW,
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&netisr_direct, 0, "enable direct dispatch");
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TUNABLE_INT("net.isr.direct", &netisr_direct);
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SYSCTL_INT(_net_isr, OID_AUTO, count, CTLFLAG_RD,
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&isrstat.isrs_count, 0, "");
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SYSCTL_INT(_net_isr, OID_AUTO, directed, CTLFLAG_RD,
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&isrstat.isrs_directed, 0, "");
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SYSCTL_INT(_net_isr, OID_AUTO, deferred, CTLFLAG_RD,
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&isrstat.isrs_deferred, 0, "");
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SYSCTL_INT(_net_isr, OID_AUTO, queued, CTLFLAG_RD,
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&isrstat.isrs_queued, 0, "");
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SYSCTL_INT(_net_isr, OID_AUTO, drop, CTLFLAG_RD,
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&isrstat.isrs_drop, 0, "");
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SYSCTL_INT(_net_isr, OID_AUTO, swi_count, CTLFLAG_RD,
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&isrstat.isrs_swi_count, 0, "");
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/*
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* Process all packets currently present in a netisr queue. Used to
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* drain an existing set of packets waiting for processing when we
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* begin direct dispatch, to avoid processing packets out of order.
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*/
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static void
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netisr_processqueue(struct netisr *ni)
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{
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struct mbuf *m;
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for (;;) {
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IF_DEQUEUE(ni->ni_queue, m);
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if (m == NULL)
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break;
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ni->ni_handler(m);
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}
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}
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/*
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* Call the netisr directly instead of queueing the packet, if possible.
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*/
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void
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netisr_dispatch(int num, struct mbuf *m)
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{
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struct netisr *ni;
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isrstat.isrs_count++; /* XXX redundant */
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KASSERT(!(num < 0 || num >= (sizeof(netisrs)/sizeof(*netisrs))),
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("bad isr %d", num));
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ni = &netisrs[num];
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if (ni->ni_queue == NULL) {
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isrstat.isrs_drop++;
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m_freem(m);
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return;
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}
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/*
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* Do direct dispatch only for MPSAFE netisrs (and
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* only when enabled). Note that when a netisr is
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* marked MPSAFE we permit multiple concurrent instances
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* to run. We guarantee only the order in which
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* packets are processed for each "dispatch point" in
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* the system (i.e. call to netisr_dispatch or
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* netisr_queue). This insures ordering of packets
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* from an interface but does not guarantee ordering
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* between multiple places in the system (e.g. IP
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* dispatched from interfaces vs. IP queued from IPSec).
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*/
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if (netisr_direct && (ni->ni_flags & NETISR_MPSAFE)) {
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isrstat.isrs_directed++;
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/*
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* NB: We used to drain the queue before handling
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* the packet but now do not. Doing so here will
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* not preserve ordering so instead we fallback to
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* guaranteeing order only from dispatch points
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* in the system (see above).
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*/
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ni->ni_handler(m);
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} else {
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isrstat.isrs_deferred++;
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if (IF_HANDOFF(ni->ni_queue, m, NULL))
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schednetisr(num);
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}
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}
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/*
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* Same as above, but always queue.
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* This is either used in places where we are not confident that
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* direct dispatch is possible, or where queueing is required.
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* It returns (0) on success and ERRNO on failure. On failure the
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* mbuf has been free'd.
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*/
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int
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netisr_queue(int num, struct mbuf *m)
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{
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struct netisr *ni;
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KASSERT(!(num < 0 || num >= (sizeof(netisrs)/sizeof(*netisrs))),
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("bad isr %d", num));
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ni = &netisrs[num];
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if (ni->ni_queue == NULL) {
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isrstat.isrs_drop++;
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m_freem(m);
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return (ENXIO);
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}
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isrstat.isrs_queued++;
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if (!IF_HANDOFF(ni->ni_queue, m, NULL))
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return (ENOBUFS); /* IF_HANDOFF has free'd the mbuf */
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schednetisr(num);
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return (0);
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}
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static void
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swi_net(void *dummy)
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{
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struct netisr *ni;
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u_int bits;
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int i;
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#ifdef DEVICE_POLLING
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const int polling = 1;
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#else
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const int polling = 0;
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#endif
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do {
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bits = atomic_readandclear_int(&netisr);
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if (bits == 0)
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break;
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while ((i = ffs(bits)) != 0) {
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isrstat.isrs_swi_count++;
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i--;
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bits &= ~(1 << i);
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ni = &netisrs[i];
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if (ni->ni_handler == NULL) {
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printf("swi_net: unregistered isr %d.\n", i);
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continue;
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}
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if ((ni->ni_flags & NETISR_MPSAFE) == 0) {
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mtx_lock(&Giant);
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if (ni->ni_queue == NULL)
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ni->ni_handler(NULL);
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else
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netisr_processqueue(ni);
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mtx_unlock(&Giant);
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} else {
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if (ni->ni_queue == NULL)
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ni->ni_handler(NULL);
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else
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netisr_processqueue(ni);
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}
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}
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} while (polling);
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}
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static void
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start_netisr(void *dummy)
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{
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if (swi_add(NULL, "net", swi_net, NULL, SWI_NET, INTR_MPSAFE, &net_ih))
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panic("start_netisr");
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}
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SYSINIT(start_netisr, SI_SUB_SOFTINTR, SI_ORDER_FIRST, start_netisr, NULL)
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