The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/net/netisr.c

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    1 /*-
    2  * Copyright (c) 2007-2009 Robert N. M. Watson
    3  * Copyright (c) 2010-2011 Juniper Networks, Inc.
    4  * All rights reserved.
    5  *
    6  * This software was developed by Robert N. M. Watson under contract
    7  * to Juniper Networks, Inc.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  *
   18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   28  * SUCH DAMAGE.
   29  */
   30 
   31 #include <sys/cdefs.h>
   32 __FBSDID("$FreeBSD: releng/9.0/sys/net/netisr.c 222531 2011-05-31 15:11:43Z nwhitehorn $");
   33 
   34 /*
   35  * netisr is a packet dispatch service, allowing synchronous (directly
   36  * dispatched) and asynchronous (deferred dispatch) processing of packets by
   37  * registered protocol handlers.  Callers pass a protocol identifier and
   38  * packet to netisr, along with a direct dispatch hint, and work will either
   39  * be immediately processed by the registered handler, or passed to a
   40  * software interrupt (SWI) thread for deferred dispatch.  Callers will
   41  * generally select one or the other based on:
   42  *
   43  * - Whether directly dispatching a netisr handler lead to code reentrance or
   44  *   lock recursion, such as entering the socket code from the socket code.
   45  * - Whether directly dispatching a netisr handler lead to recursive
   46  *   processing, such as when decapsulating several wrapped layers of tunnel
   47  *   information (IPSEC within IPSEC within ...).
   48  *
   49  * Maintaining ordering for protocol streams is a critical design concern.
   50  * Enforcing ordering limits the opportunity for concurrency, but maintains
   51  * the strong ordering requirements found in some protocols, such as TCP.  Of
   52  * related concern is CPU affinity--it is desirable to process all data
   53  * associated with a particular stream on the same CPU over time in order to
   54  * avoid acquiring locks associated with the connection on different CPUs,
   55  * keep connection data in one cache, and to generally encourage associated
   56  * user threads to live on the same CPU as the stream.  It's also desirable
   57  * to avoid lock migration and contention where locks are associated with
   58  * more than one flow.
   59  *
   60  * netisr supports several policy variations, represented by the
   61  * NETISR_POLICY_* constants, allowing protocols to play various roles in
   62  * identifying flows, assigning work to CPUs, etc.  These are described in
   63  * netisr.h.
   64  */
   65 
   66 #include "opt_ddb.h"
   67 #include "opt_device_polling.h"
   68 
   69 #include <sys/param.h>
   70 #include <sys/bus.h>
   71 #include <sys/kernel.h>
   72 #include <sys/kthread.h>
   73 #include <sys/interrupt.h>
   74 #include <sys/lock.h>
   75 #include <sys/mbuf.h>
   76 #include <sys/mutex.h>
   77 #include <sys/pcpu.h>
   78 #include <sys/proc.h>
   79 #include <sys/rmlock.h>
   80 #include <sys/sched.h>
   81 #include <sys/smp.h>
   82 #include <sys/socket.h>
   83 #include <sys/sysctl.h>
   84 #include <sys/systm.h>
   85 
   86 #ifdef DDB
   87 #include <ddb/ddb.h>
   88 #endif
   89 
   90 #define _WANT_NETISR_INTERNAL   /* Enable definitions from netisr_internal.h */
   91 #include <net/if.h>
   92 #include <net/if_var.h>
   93 #include <net/netisr.h>
   94 #include <net/netisr_internal.h>
   95 #include <net/vnet.h>
   96 
   97 /*-
   98  * Synchronize use and modification of the registered netisr data structures;
   99  * acquire a read lock while modifying the set of registered protocols to
  100  * prevent partially registered or unregistered protocols from being run.
  101  *
  102  * The following data structures and fields are protected by this lock:
  103  *
  104  * - The netisr_proto array, including all fields of struct netisr_proto.
  105  * - The nws array, including all fields of struct netisr_worker.
  106  * - The nws_array array.
  107  *
  108  * Note: the NETISR_LOCKING define controls whether read locks are acquired
  109  * in packet processing paths requiring netisr registration stability.  This
  110  * is disabled by default as it can lead to measurable performance
  111  * degradation even with rmlocks (3%-6% for loopback ping-pong traffic), and
  112  * because netisr registration and unregistration is extremely rare at
  113  * runtime.  If it becomes more common, this decision should be revisited.
  114  *
  115  * XXXRW: rmlocks don't support assertions.
  116  */
  117 static struct rmlock    netisr_rmlock;
  118 #define NETISR_LOCK_INIT()      rm_init_flags(&netisr_rmlock, "netisr", \
  119                                     RM_NOWITNESS)
  120 #define NETISR_LOCK_ASSERT()
  121 #define NETISR_RLOCK(tracker)   rm_rlock(&netisr_rmlock, (tracker))
  122 #define NETISR_RUNLOCK(tracker) rm_runlock(&netisr_rmlock, (tracker))
  123 #define NETISR_WLOCK()          rm_wlock(&netisr_rmlock)
  124 #define NETISR_WUNLOCK()        rm_wunlock(&netisr_rmlock)
  125 /* #define      NETISR_LOCKING */
  126 
  127 SYSCTL_NODE(_net, OID_AUTO, isr, CTLFLAG_RW, 0, "netisr");
  128 
  129 /*-
  130  * Three global direct dispatch policies are supported:
  131  *
  132  * NETISR_DISPATCH_QUEUED: All work is deferred for a netisr, regardless of
  133  * context (may be overriden by protocols).
  134  *
  135  * NETISR_DISPATCH_HYBRID: If the executing context allows direct dispatch,
  136  * and we're running on the CPU the work would be performed on, then direct
  137  * dispatch it if it wouldn't violate ordering constraints on the workstream.
  138  *
  139  * NETISR_DISPATCH_DIRECT: If the executing context allows direct dispatch,
  140  * always direct dispatch.  (The default.)
  141  *
  142  * Notice that changing the global policy could lead to short periods of
  143  * misordered processing, but this is considered acceptable as compared to
  144  * the complexity of enforcing ordering during policy changes.  Protocols can
  145  * override the global policy (when they're not doing that, they select
  146  * NETISR_DISPATCH_DEFAULT).
  147  */
  148 #define NETISR_DISPATCH_POLICY_DEFAULT  NETISR_DISPATCH_DIRECT
  149 #define NETISR_DISPATCH_POLICY_MAXSTR   20 /* Used for temporary buffers. */
  150 static u_int    netisr_dispatch_policy = NETISR_DISPATCH_POLICY_DEFAULT;
  151 static int      sysctl_netisr_dispatch_policy(SYSCTL_HANDLER_ARGS);
  152 SYSCTL_PROC(_net_isr, OID_AUTO, dispatch, CTLTYPE_STRING | CTLFLAG_RW |
  153     CTLFLAG_TUN, 0, 0, sysctl_netisr_dispatch_policy, "A",
  154     "netisr dispatch policy");
  155 
  156 /*
  157  * These sysctls were used in previous versions to control and export
  158  * dispatch policy state.  Now, we provide read-only export via them so that
  159  * older netstat binaries work.  At some point they can be garbage collected.
  160  */
  161 static int      netisr_direct_force;
  162 SYSCTL_INT(_net_isr, OID_AUTO, direct_force, CTLFLAG_RD,
  163     &netisr_direct_force, 0, "compat: force direct dispatch");
  164 
  165 static int      netisr_direct;
  166 SYSCTL_INT(_net_isr, OID_AUTO, direct, CTLFLAG_RD, &netisr_direct, 0,
  167     "compat: enable direct dispatch");
  168 
  169 /*
  170  * Allow the administrator to limit the number of threads (CPUs) to use for
  171  * netisr.  We don't check netisr_maxthreads before creating the thread for
  172  * CPU 0, so in practice we ignore values <= 1.  This must be set at boot.
  173  * We will create at most one thread per CPU.
  174  */
  175 static int      netisr_maxthreads = -1;         /* Max number of threads. */
  176 TUNABLE_INT("net.isr.maxthreads", &netisr_maxthreads);
  177 SYSCTL_INT(_net_isr, OID_AUTO, maxthreads, CTLFLAG_RDTUN,
  178     &netisr_maxthreads, 0,
  179     "Use at most this many CPUs for netisr processing");
  180 
  181 static int      netisr_bindthreads = 0;         /* Bind threads to CPUs. */
  182 TUNABLE_INT("net.isr.bindthreads", &netisr_bindthreads);
  183 SYSCTL_INT(_net_isr, OID_AUTO, bindthreads, CTLFLAG_RDTUN,
  184     &netisr_bindthreads, 0, "Bind netisr threads to CPUs.");
  185 
  186 /*
  187  * Limit per-workstream mbuf queue limits s to at most net.isr.maxqlimit,
  188  * both for initial configuration and later modification using
  189  * netisr_setqlimit().
  190  */
  191 #define NETISR_DEFAULT_MAXQLIMIT        10240
  192 static u_int    netisr_maxqlimit = NETISR_DEFAULT_MAXQLIMIT;
  193 TUNABLE_INT("net.isr.maxqlimit", &netisr_maxqlimit);
  194 SYSCTL_UINT(_net_isr, OID_AUTO, maxqlimit, CTLFLAG_RDTUN,
  195     &netisr_maxqlimit, 0,
  196     "Maximum netisr per-protocol, per-CPU queue depth.");
  197 
  198 /*
  199  * The default per-workstream mbuf queue limit for protocols that don't
  200  * initialize the nh_qlimit field of their struct netisr_handler.  If this is
  201  * set above netisr_maxqlimit, we truncate it to the maximum during boot.
  202  */
  203 #define NETISR_DEFAULT_DEFAULTQLIMIT    256
  204 static u_int    netisr_defaultqlimit = NETISR_DEFAULT_DEFAULTQLIMIT;
  205 TUNABLE_INT("net.isr.defaultqlimit", &netisr_defaultqlimit);
  206 SYSCTL_UINT(_net_isr, OID_AUTO, defaultqlimit, CTLFLAG_RDTUN,
  207     &netisr_defaultqlimit, 0,
  208     "Default netisr per-protocol, per-CPU queue limit if not set by protocol");
  209 
  210 /*
  211  * Store and export the compile-time constant NETISR_MAXPROT limit on the
  212  * number of protocols that can register with netisr at a time.  This is
  213  * required for crashdump analysis, as it sizes netisr_proto[].
  214  */
  215 static u_int    netisr_maxprot = NETISR_MAXPROT;
  216 SYSCTL_UINT(_net_isr, OID_AUTO, maxprot, CTLFLAG_RD,
  217     &netisr_maxprot, 0,
  218     "Compile-time limit on the number of protocols supported by netisr.");
  219 
  220 /*
  221  * The netisr_proto array describes all registered protocols, indexed by
  222  * protocol number.  See netisr_internal.h for more details.
  223  */
  224 static struct netisr_proto      netisr_proto[NETISR_MAXPROT];
  225 
  226 /*
  227  * Per-CPU workstream data.  See netisr_internal.h for more details.
  228  */
  229 DPCPU_DEFINE(struct netisr_workstream, nws);
  230 
  231 /*
  232  * Map contiguous values between 0 and nws_count into CPU IDs appropriate for
  233  * accessing workstreams.  This allows constructions of the form
  234  * DPCPU_ID_GET(nws_array[arbitraryvalue % nws_count], nws).
  235  */
  236 static u_int                             nws_array[MAXCPU];
  237 
  238 /*
  239  * Number of registered workstreams.  Will be at most the number of running
  240  * CPUs once fully started.
  241  */
  242 static u_int                             nws_count;
  243 SYSCTL_UINT(_net_isr, OID_AUTO, numthreads, CTLFLAG_RD,
  244     &nws_count, 0, "Number of extant netisr threads.");
  245 
  246 /*
  247  * Synchronization for each workstream: a mutex protects all mutable fields
  248  * in each stream, including per-protocol state (mbuf queues).  The SWI is
  249  * woken up if asynchronous dispatch is required.
  250  */
  251 #define NWS_LOCK(s)             mtx_lock(&(s)->nws_mtx)
  252 #define NWS_LOCK_ASSERT(s)      mtx_assert(&(s)->nws_mtx, MA_OWNED)
  253 #define NWS_UNLOCK(s)           mtx_unlock(&(s)->nws_mtx)
  254 #define NWS_SIGNAL(s)           swi_sched((s)->nws_swi_cookie, 0)
  255 
  256 /*
  257  * Utility routines for protocols that implement their own mapping of flows
  258  * to CPUs.
  259  */
  260 u_int
  261 netisr_get_cpucount(void)
  262 {
  263 
  264         return (nws_count);
  265 }
  266 
  267 u_int
  268 netisr_get_cpuid(u_int cpunumber)
  269 {
  270 
  271         KASSERT(cpunumber < nws_count, ("%s: %u > %u", __func__, cpunumber,
  272             nws_count));
  273 
  274         return (nws_array[cpunumber]);
  275 }
  276 
  277 /*
  278  * The default implementation of flow -> CPU ID mapping.
  279  *
  280  * Non-static so that protocols can use it to map their own work to specific
  281  * CPUs in a manner consistent to netisr for affinity purposes.
  282  */
  283 u_int
  284 netisr_default_flow2cpu(u_int flowid)
  285 {
  286 
  287         return (nws_array[flowid % nws_count]);
  288 }
  289 
  290 /*
  291  * Dispatch tunable and sysctl configuration.
  292  */
  293 struct netisr_dispatch_table_entry {
  294         u_int            ndte_policy;
  295         const char      *ndte_policy_str;
  296 };
  297 static const struct netisr_dispatch_table_entry netisr_dispatch_table[] = {
  298         { NETISR_DISPATCH_DEFAULT, "default" },
  299         { NETISR_DISPATCH_DEFERRED, "deferred" },
  300         { NETISR_DISPATCH_HYBRID, "hybrid" },
  301         { NETISR_DISPATCH_DIRECT, "direct" },
  302 };
  303 static const u_int netisr_dispatch_table_len =
  304     (sizeof(netisr_dispatch_table) / sizeof(netisr_dispatch_table[0]));
  305 
  306 static void
  307 netisr_dispatch_policy_to_str(u_int dispatch_policy, char *buffer,
  308     u_int buflen)
  309 {
  310         const struct netisr_dispatch_table_entry *ndtep;
  311         const char *str;
  312         u_int i;
  313 
  314         str = "unknown";
  315         for (i = 0; i < netisr_dispatch_table_len; i++) {
  316                 ndtep = &netisr_dispatch_table[i];
  317                 if (ndtep->ndte_policy == dispatch_policy) {
  318                         str = ndtep->ndte_policy_str;
  319                         break;
  320                 }
  321         }
  322         snprintf(buffer, buflen, "%s", str);
  323 }
  324 
  325 static int
  326 netisr_dispatch_policy_from_str(const char *str, u_int *dispatch_policyp)
  327 {
  328         const struct netisr_dispatch_table_entry *ndtep;
  329         u_int i;
  330 
  331         for (i = 0; i < netisr_dispatch_table_len; i++) {
  332                 ndtep = &netisr_dispatch_table[i];
  333                 if (strcmp(ndtep->ndte_policy_str, str) == 0) {
  334                         *dispatch_policyp = ndtep->ndte_policy;
  335                         return (0);
  336                 }
  337         }
  338         return (EINVAL);
  339 }
  340 
  341 static void
  342 netisr_dispatch_policy_compat(void)
  343 {
  344 
  345         switch (netisr_dispatch_policy) {
  346         case NETISR_DISPATCH_DEFERRED:
  347                 netisr_direct_force = 0;
  348                 netisr_direct = 0;
  349                 break;
  350 
  351         case NETISR_DISPATCH_HYBRID:
  352                 netisr_direct_force = 0;
  353                 netisr_direct = 1;
  354                 break;
  355 
  356         case NETISR_DISPATCH_DIRECT:
  357                 netisr_direct_force = 1;
  358                 netisr_direct = 1;
  359                 break;
  360 
  361         default:
  362                 panic("%s: unknown policy %u", __func__,
  363                     netisr_dispatch_policy);
  364         }
  365 }
  366 
  367 static int
  368 sysctl_netisr_dispatch_policy(SYSCTL_HANDLER_ARGS)
  369 {
  370         char tmp[NETISR_DISPATCH_POLICY_MAXSTR];
  371         u_int dispatch_policy;
  372         int error;
  373 
  374         netisr_dispatch_policy_to_str(netisr_dispatch_policy, tmp,
  375             sizeof(tmp));
  376         error = sysctl_handle_string(oidp, tmp, sizeof(tmp), req);
  377         if (error == 0 && req->newptr != NULL) {
  378                 error = netisr_dispatch_policy_from_str(tmp,
  379                     &dispatch_policy);
  380                 if (error == 0 && dispatch_policy == NETISR_DISPATCH_DEFAULT)
  381                         error = EINVAL;
  382                 if (error == 0) {
  383                         netisr_dispatch_policy = dispatch_policy;
  384                         netisr_dispatch_policy_compat();
  385                 }
  386         }
  387         return (error);
  388 }
  389 
  390 /*
  391  * Register a new netisr handler, which requires initializing per-protocol
  392  * fields for each workstream.  All netisr work is briefly suspended while
  393  * the protocol is installed.
  394  */
  395 void
  396 netisr_register(const struct netisr_handler *nhp)
  397 {
  398         struct netisr_work *npwp;
  399         const char *name;
  400         u_int i, proto;
  401 
  402         proto = nhp->nh_proto;
  403         name = nhp->nh_name;
  404 
  405         /*
  406          * Test that the requested registration is valid.
  407          */
  408         KASSERT(nhp->nh_name != NULL,
  409             ("%s: nh_name NULL for %u", __func__, proto));
  410         KASSERT(nhp->nh_handler != NULL,
  411             ("%s: nh_handler NULL for %s", __func__, name));
  412         KASSERT(nhp->nh_policy == NETISR_POLICY_SOURCE ||
  413             nhp->nh_policy == NETISR_POLICY_FLOW ||
  414             nhp->nh_policy == NETISR_POLICY_CPU,
  415             ("%s: unsupported nh_policy %u for %s", __func__,
  416             nhp->nh_policy, name));
  417         KASSERT(nhp->nh_policy == NETISR_POLICY_FLOW ||
  418             nhp->nh_m2flow == NULL,
  419             ("%s: nh_policy != FLOW but m2flow defined for %s", __func__,
  420             name));
  421         KASSERT(nhp->nh_policy == NETISR_POLICY_CPU || nhp->nh_m2cpuid == NULL,
  422             ("%s: nh_policy != CPU but m2cpuid defined for %s", __func__,
  423             name));
  424         KASSERT(nhp->nh_policy != NETISR_POLICY_CPU || nhp->nh_m2cpuid != NULL,
  425             ("%s: nh_policy == CPU but m2cpuid not defined for %s", __func__,
  426             name));
  427         KASSERT(nhp->nh_dispatch == NETISR_DISPATCH_DEFAULT ||
  428             nhp->nh_dispatch == NETISR_DISPATCH_DEFERRED ||
  429             nhp->nh_dispatch == NETISR_DISPATCH_HYBRID ||
  430             nhp->nh_dispatch == NETISR_DISPATCH_DIRECT,
  431             ("%s: invalid nh_dispatch (%u)", __func__, nhp->nh_dispatch));
  432 
  433         KASSERT(proto < NETISR_MAXPROT,
  434             ("%s(%u, %s): protocol too big", __func__, proto, name));
  435 
  436         /*
  437          * Test that no existing registration exists for this protocol.
  438          */
  439         NETISR_WLOCK();
  440         KASSERT(netisr_proto[proto].np_name == NULL,
  441             ("%s(%u, %s): name present", __func__, proto, name));
  442         KASSERT(netisr_proto[proto].np_handler == NULL,
  443             ("%s(%u, %s): handler present", __func__, proto, name));
  444 
  445         netisr_proto[proto].np_name = name;
  446         netisr_proto[proto].np_handler = nhp->nh_handler;
  447         netisr_proto[proto].np_m2flow = nhp->nh_m2flow;
  448         netisr_proto[proto].np_m2cpuid = nhp->nh_m2cpuid;
  449         netisr_proto[proto].np_drainedcpu = nhp->nh_drainedcpu;
  450         if (nhp->nh_qlimit == 0)
  451                 netisr_proto[proto].np_qlimit = netisr_defaultqlimit;
  452         else if (nhp->nh_qlimit > netisr_maxqlimit) {
  453                 printf("%s: %s requested queue limit %u capped to "
  454                     "net.isr.maxqlimit %u\n", __func__, name, nhp->nh_qlimit,
  455                     netisr_maxqlimit);
  456                 netisr_proto[proto].np_qlimit = netisr_maxqlimit;
  457         } else
  458                 netisr_proto[proto].np_qlimit = nhp->nh_qlimit;
  459         netisr_proto[proto].np_policy = nhp->nh_policy;
  460         netisr_proto[proto].np_dispatch = nhp->nh_dispatch;
  461         CPU_FOREACH(i) {
  462                 npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
  463                 bzero(npwp, sizeof(*npwp));
  464                 npwp->nw_qlimit = netisr_proto[proto].np_qlimit;
  465         }
  466         NETISR_WUNLOCK();
  467 }
  468 
  469 /*
  470  * Clear drop counters across all workstreams for a protocol.
  471  */
  472 void
  473 netisr_clearqdrops(const struct netisr_handler *nhp)
  474 {
  475         struct netisr_work *npwp;
  476 #ifdef INVARIANTS
  477         const char *name;
  478 #endif
  479         u_int i, proto;
  480 
  481         proto = nhp->nh_proto;
  482 #ifdef INVARIANTS
  483         name = nhp->nh_name;
  484 #endif
  485         KASSERT(proto < NETISR_MAXPROT,
  486             ("%s(%u): protocol too big for %s", __func__, proto, name));
  487 
  488         NETISR_WLOCK();
  489         KASSERT(netisr_proto[proto].np_handler != NULL,
  490             ("%s(%u): protocol not registered for %s", __func__, proto,
  491             name));
  492 
  493         CPU_FOREACH(i) {
  494                 npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
  495                 npwp->nw_qdrops = 0;
  496         }
  497         NETISR_WUNLOCK();
  498 }
  499 
  500 /*
  501  * Query current drop counters across all workstreams for a protocol.
  502  */
  503 void
  504 netisr_getqdrops(const struct netisr_handler *nhp, u_int64_t *qdropp)
  505 {
  506         struct netisr_work *npwp;
  507         struct rm_priotracker tracker;
  508 #ifdef INVARIANTS
  509         const char *name;
  510 #endif
  511         u_int i, proto;
  512 
  513         *qdropp = 0;
  514         proto = nhp->nh_proto;
  515 #ifdef INVARIANTS
  516         name = nhp->nh_name;
  517 #endif
  518         KASSERT(proto < NETISR_MAXPROT,
  519             ("%s(%u): protocol too big for %s", __func__, proto, name));
  520 
  521         NETISR_RLOCK(&tracker);
  522         KASSERT(netisr_proto[proto].np_handler != NULL,
  523             ("%s(%u): protocol not registered for %s", __func__, proto,
  524             name));
  525 
  526         CPU_FOREACH(i) {
  527                 npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
  528                 *qdropp += npwp->nw_qdrops;
  529         }
  530         NETISR_RUNLOCK(&tracker);
  531 }
  532 
  533 /*
  534  * Query current per-workstream queue limit for a protocol.
  535  */
  536 void
  537 netisr_getqlimit(const struct netisr_handler *nhp, u_int *qlimitp)
  538 {
  539         struct rm_priotracker tracker;
  540 #ifdef INVARIANTS
  541         const char *name;
  542 #endif
  543         u_int proto;
  544 
  545         proto = nhp->nh_proto;
  546 #ifdef INVARIANTS
  547         name = nhp->nh_name;
  548 #endif
  549         KASSERT(proto < NETISR_MAXPROT,
  550             ("%s(%u): protocol too big for %s", __func__, proto, name));
  551 
  552         NETISR_RLOCK(&tracker);
  553         KASSERT(netisr_proto[proto].np_handler != NULL,
  554             ("%s(%u): protocol not registered for %s", __func__, proto,
  555             name));
  556         *qlimitp = netisr_proto[proto].np_qlimit;
  557         NETISR_RUNLOCK(&tracker);
  558 }
  559 
  560 /*
  561  * Update the queue limit across per-workstream queues for a protocol.  We
  562  * simply change the limits, and don't drain overflowed packets as they will
  563  * (hopefully) take care of themselves shortly.
  564  */
  565 int
  566 netisr_setqlimit(const struct netisr_handler *nhp, u_int qlimit)
  567 {
  568         struct netisr_work *npwp;
  569 #ifdef INVARIANTS
  570         const char *name;
  571 #endif
  572         u_int i, proto;
  573 
  574         if (qlimit > netisr_maxqlimit)
  575                 return (EINVAL);
  576 
  577         proto = nhp->nh_proto;
  578 #ifdef INVARIANTS
  579         name = nhp->nh_name;
  580 #endif
  581         KASSERT(proto < NETISR_MAXPROT,
  582             ("%s(%u): protocol too big for %s", __func__, proto, name));
  583 
  584         NETISR_WLOCK();
  585         KASSERT(netisr_proto[proto].np_handler != NULL,
  586             ("%s(%u): protocol not registered for %s", __func__, proto,
  587             name));
  588 
  589         netisr_proto[proto].np_qlimit = qlimit;
  590         CPU_FOREACH(i) {
  591                 npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
  592                 npwp->nw_qlimit = qlimit;
  593         }
  594         NETISR_WUNLOCK();
  595         return (0);
  596 }
  597 
  598 /*
  599  * Drain all packets currently held in a particular protocol work queue.
  600  */
  601 static void
  602 netisr_drain_proto(struct netisr_work *npwp)
  603 {
  604         struct mbuf *m;
  605 
  606         /*
  607          * We would assert the lock on the workstream but it's not passed in.
  608          */
  609         while ((m = npwp->nw_head) != NULL) {
  610                 npwp->nw_head = m->m_nextpkt;
  611                 m->m_nextpkt = NULL;
  612                 if (npwp->nw_head == NULL)
  613                         npwp->nw_tail = NULL;
  614                 npwp->nw_len--;
  615                 m_freem(m);
  616         }
  617         KASSERT(npwp->nw_tail == NULL, ("%s: tail", __func__));
  618         KASSERT(npwp->nw_len == 0, ("%s: len", __func__));
  619 }
  620 
  621 /*
  622  * Remove the registration of a network protocol, which requires clearing
  623  * per-protocol fields across all workstreams, including freeing all mbufs in
  624  * the queues at time of unregister.  All work in netisr is briefly suspended
  625  * while this takes place.
  626  */
  627 void
  628 netisr_unregister(const struct netisr_handler *nhp)
  629 {
  630         struct netisr_work *npwp;
  631 #ifdef INVARIANTS
  632         const char *name;
  633 #endif
  634         u_int i, proto;
  635 
  636         proto = nhp->nh_proto;
  637 #ifdef INVARIANTS
  638         name = nhp->nh_name;
  639 #endif
  640         KASSERT(proto < NETISR_MAXPROT,
  641             ("%s(%u): protocol too big for %s", __func__, proto, name));
  642 
  643         NETISR_WLOCK();
  644         KASSERT(netisr_proto[proto].np_handler != NULL,
  645             ("%s(%u): protocol not registered for %s", __func__, proto,
  646             name));
  647 
  648         netisr_proto[proto].np_name = NULL;
  649         netisr_proto[proto].np_handler = NULL;
  650         netisr_proto[proto].np_m2flow = NULL;
  651         netisr_proto[proto].np_m2cpuid = NULL;
  652         netisr_proto[proto].np_qlimit = 0;
  653         netisr_proto[proto].np_policy = 0;
  654         CPU_FOREACH(i) {
  655                 npwp = &(DPCPU_ID_PTR(i, nws))->nws_work[proto];
  656                 netisr_drain_proto(npwp);
  657                 bzero(npwp, sizeof(*npwp));
  658         }
  659         NETISR_WUNLOCK();
  660 }
  661 
  662 /*
  663  * Compose the global and per-protocol policies on dispatch, and return the
  664  * dispatch policy to use.
  665  */
  666 static u_int
  667 netisr_get_dispatch(struct netisr_proto *npp)
  668 {
  669 
  670         /*
  671          * Protocol-specific configuration overrides the global default.
  672          */
  673         if (npp->np_dispatch != NETISR_DISPATCH_DEFAULT)
  674                 return (npp->np_dispatch);
  675         return (netisr_dispatch_policy);
  676 }
  677 
  678 /*
  679  * Look up the workstream given a packet and source identifier.  Do this by
  680  * checking the protocol's policy, and optionally call out to the protocol
  681  * for assistance if required.
  682  */
  683 static struct mbuf *
  684 netisr_select_cpuid(struct netisr_proto *npp, u_int dispatch_policy,
  685     uintptr_t source, struct mbuf *m, u_int *cpuidp)
  686 {
  687         struct ifnet *ifp;
  688         u_int policy;
  689 
  690         NETISR_LOCK_ASSERT();
  691 
  692         /*
  693          * In the event we have only one worker, shortcut and deliver to it
  694          * without further ado.
  695          */
  696         if (nws_count == 1) {
  697                 *cpuidp = nws_array[0];
  698                 return (m);
  699         }
  700 
  701         /*
  702          * What happens next depends on the policy selected by the protocol.
  703          * If we want to support per-interface policies, we should do that
  704          * here first.
  705          */
  706         policy = npp->np_policy;
  707         if (policy == NETISR_POLICY_CPU) {
  708                 m = npp->np_m2cpuid(m, source, cpuidp);
  709                 if (m == NULL)
  710                         return (NULL);
  711 
  712                 /*
  713                  * It's possible for a protocol not to have a good idea about
  714                  * where to process a packet, in which case we fall back on
  715                  * the netisr code to decide.  In the hybrid case, return the
  716                  * current CPU ID, which will force an immediate direct
  717                  * dispatch.  In the queued case, fall back on the SOURCE
  718                  * policy.
  719                  */
  720                 if (*cpuidp != NETISR_CPUID_NONE)
  721                         return (m);
  722                 if (dispatch_policy == NETISR_DISPATCH_HYBRID) {
  723                         *cpuidp = curcpu;
  724                         return (m);
  725                 }
  726                 policy = NETISR_POLICY_SOURCE;
  727         }
  728 
  729         if (policy == NETISR_POLICY_FLOW) {
  730                 if (!(m->m_flags & M_FLOWID) && npp->np_m2flow != NULL) {
  731                         m = npp->np_m2flow(m, source);
  732                         if (m == NULL)
  733                                 return (NULL);
  734                 }
  735                 if (m->m_flags & M_FLOWID) {
  736                         *cpuidp =
  737                             netisr_default_flow2cpu(m->m_pkthdr.flowid);
  738                         return (m);
  739                 }
  740                 policy = NETISR_POLICY_SOURCE;
  741         }
  742 
  743         KASSERT(policy == NETISR_POLICY_SOURCE,
  744             ("%s: invalid policy %u for %s", __func__, npp->np_policy,
  745             npp->np_name));
  746 
  747         ifp = m->m_pkthdr.rcvif;
  748         if (ifp != NULL)
  749                 *cpuidp = nws_array[(ifp->if_index + source) % nws_count];
  750         else
  751                 *cpuidp = nws_array[source % nws_count];
  752         return (m);
  753 }
  754 
  755 /*
  756  * Process packets associated with a workstream and protocol.  For reasons of
  757  * fairness, we process up to one complete netisr queue at a time, moving the
  758  * queue to a stack-local queue for processing, but do not loop refreshing
  759  * from the global queue.  The caller is responsible for deciding whether to
  760  * loop, and for setting the NWS_RUNNING flag.  The passed workstream will be
  761  * locked on entry and relocked before return, but will be released while
  762  * processing.  The number of packets processed is returned.
  763  */
  764 static u_int
  765 netisr_process_workstream_proto(struct netisr_workstream *nwsp, u_int proto)
  766 {
  767         struct netisr_work local_npw, *npwp;
  768         u_int handled;
  769         struct mbuf *m;
  770 
  771         NETISR_LOCK_ASSERT();
  772         NWS_LOCK_ASSERT(nwsp);
  773 
  774         KASSERT(nwsp->nws_flags & NWS_RUNNING,
  775             ("%s(%u): not running", __func__, proto));
  776         KASSERT(proto >= 0 && proto < NETISR_MAXPROT,
  777             ("%s(%u): invalid proto\n", __func__, proto));
  778 
  779         npwp = &nwsp->nws_work[proto];
  780         if (npwp->nw_len == 0)
  781                 return (0);
  782 
  783         /*
  784          * Move the global work queue to a thread-local work queue.
  785          *
  786          * Notice that this means the effective maximum length of the queue
  787          * is actually twice that of the maximum queue length specified in
  788          * the protocol registration call.
  789          */
  790         handled = npwp->nw_len;
  791         local_npw = *npwp;
  792         npwp->nw_head = NULL;
  793         npwp->nw_tail = NULL;
  794         npwp->nw_len = 0;
  795         nwsp->nws_pendingbits &= ~(1 << proto);
  796         NWS_UNLOCK(nwsp);
  797         while ((m = local_npw.nw_head) != NULL) {
  798                 local_npw.nw_head = m->m_nextpkt;
  799                 m->m_nextpkt = NULL;
  800                 if (local_npw.nw_head == NULL)
  801                         local_npw.nw_tail = NULL;
  802                 local_npw.nw_len--;
  803                 VNET_ASSERT(m->m_pkthdr.rcvif != NULL,
  804                     ("%s:%d rcvif == NULL: m=%p", __func__, __LINE__, m));
  805                 CURVNET_SET(m->m_pkthdr.rcvif->if_vnet);
  806                 netisr_proto[proto].np_handler(m);
  807                 CURVNET_RESTORE();
  808         }
  809         KASSERT(local_npw.nw_len == 0,
  810             ("%s(%u): len %u", __func__, proto, local_npw.nw_len));
  811         if (netisr_proto[proto].np_drainedcpu)
  812                 netisr_proto[proto].np_drainedcpu(nwsp->nws_cpu);
  813         NWS_LOCK(nwsp);
  814         npwp->nw_handled += handled;
  815         return (handled);
  816 }
  817 
  818 /*
  819  * SWI handler for netisr -- processes packets in a set of workstreams that
  820  * it owns, woken up by calls to NWS_SIGNAL().  If this workstream is already
  821  * being direct dispatched, go back to sleep and wait for the dispatching
  822  * thread to wake us up again.
  823  */
  824 static void
  825 swi_net(void *arg)
  826 {
  827 #ifdef NETISR_LOCKING
  828         struct rm_priotracker tracker;
  829 #endif
  830         struct netisr_workstream *nwsp;
  831         u_int bits, prot;
  832 
  833         nwsp = arg;
  834 
  835 #ifdef DEVICE_POLLING
  836         KASSERT(nws_count == 1,
  837             ("%s: device_polling but nws_count != 1", __func__));
  838         netisr_poll();
  839 #endif
  840 #ifdef NETISR_LOCKING
  841         NETISR_RLOCK(&tracker);
  842 #endif
  843         NWS_LOCK(nwsp);
  844         KASSERT(!(nwsp->nws_flags & NWS_RUNNING), ("swi_net: running"));
  845         if (nwsp->nws_flags & NWS_DISPATCHING)
  846                 goto out;
  847         nwsp->nws_flags |= NWS_RUNNING;
  848         nwsp->nws_flags &= ~NWS_SCHEDULED;
  849         while ((bits = nwsp->nws_pendingbits) != 0) {
  850                 while ((prot = ffs(bits)) != 0) {
  851                         prot--;
  852                         bits &= ~(1 << prot);
  853                         (void)netisr_process_workstream_proto(nwsp, prot);
  854                 }
  855         }
  856         nwsp->nws_flags &= ~NWS_RUNNING;
  857 out:
  858         NWS_UNLOCK(nwsp);
  859 #ifdef NETISR_LOCKING
  860         NETISR_RUNLOCK(&tracker);
  861 #endif
  862 #ifdef DEVICE_POLLING
  863         netisr_pollmore();
  864 #endif
  865 }
  866 
  867 static int
  868 netisr_queue_workstream(struct netisr_workstream *nwsp, u_int proto,
  869     struct netisr_work *npwp, struct mbuf *m, int *dosignalp)
  870 {
  871 
  872         NWS_LOCK_ASSERT(nwsp);
  873 
  874         *dosignalp = 0;
  875         if (npwp->nw_len < npwp->nw_qlimit) {
  876                 m->m_nextpkt = NULL;
  877                 if (npwp->nw_head == NULL) {
  878                         npwp->nw_head = m;
  879                         npwp->nw_tail = m;
  880                 } else {
  881                         npwp->nw_tail->m_nextpkt = m;
  882                         npwp->nw_tail = m;
  883                 }
  884                 npwp->nw_len++;
  885                 if (npwp->nw_len > npwp->nw_watermark)
  886                         npwp->nw_watermark = npwp->nw_len;
  887 
  888                 /*
  889                  * We must set the bit regardless of NWS_RUNNING, so that
  890                  * swi_net() keeps calling netisr_process_workstream_proto().
  891                  */
  892                 nwsp->nws_pendingbits |= (1 << proto);
  893                 if (!(nwsp->nws_flags & 
  894                     (NWS_RUNNING | NWS_DISPATCHING | NWS_SCHEDULED))) {
  895                         nwsp->nws_flags |= NWS_SCHEDULED;
  896                         *dosignalp = 1; /* Defer until unlocked. */
  897                 }
  898                 npwp->nw_queued++;
  899                 return (0);
  900         } else {
  901                 m_freem(m);
  902                 npwp->nw_qdrops++;
  903                 return (ENOBUFS);
  904         }
  905 }
  906 
  907 static int
  908 netisr_queue_internal(u_int proto, struct mbuf *m, u_int cpuid)
  909 {
  910         struct netisr_workstream *nwsp;
  911         struct netisr_work *npwp;
  912         int dosignal, error;
  913 
  914 #ifdef NETISR_LOCKING
  915         NETISR_LOCK_ASSERT();
  916 #endif
  917         KASSERT(cpuid <= mp_maxid, ("%s: cpuid too big (%u, %u)", __func__,
  918             cpuid, mp_maxid));
  919         KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__, cpuid));
  920 
  921         dosignal = 0;
  922         error = 0;
  923         nwsp = DPCPU_ID_PTR(cpuid, nws);
  924         npwp = &nwsp->nws_work[proto];
  925         NWS_LOCK(nwsp);
  926         error = netisr_queue_workstream(nwsp, proto, npwp, m, &dosignal);
  927         NWS_UNLOCK(nwsp);
  928         if (dosignal)
  929                 NWS_SIGNAL(nwsp);
  930         return (error);
  931 }
  932 
  933 int
  934 netisr_queue_src(u_int proto, uintptr_t source, struct mbuf *m)
  935 {
  936 #ifdef NETISR_LOCKING
  937         struct rm_priotracker tracker;
  938 #endif
  939         u_int cpuid;
  940         int error;
  941 
  942         KASSERT(proto < NETISR_MAXPROT,
  943             ("%s: invalid proto %u", __func__, proto));
  944 
  945 #ifdef NETISR_LOCKING
  946         NETISR_RLOCK(&tracker);
  947 #endif
  948         KASSERT(netisr_proto[proto].np_handler != NULL,
  949             ("%s: invalid proto %u", __func__, proto));
  950 
  951         m = netisr_select_cpuid(&netisr_proto[proto], NETISR_DISPATCH_DEFERRED,
  952             source, m, &cpuid);
  953         if (m != NULL) {
  954                 KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__,
  955                     cpuid));
  956                 error = netisr_queue_internal(proto, m, cpuid);
  957         } else
  958                 error = ENOBUFS;
  959 #ifdef NETISR_LOCKING
  960         NETISR_RUNLOCK(&tracker);
  961 #endif
  962         return (error);
  963 }
  964 
  965 int
  966 netisr_queue(u_int proto, struct mbuf *m)
  967 {
  968 
  969         return (netisr_queue_src(proto, 0, m));
  970 }
  971 
  972 /*
  973  * Dispatch a packet for netisr processing; direct dispatch is permitted by
  974  * calling context.
  975  */
  976 int
  977 netisr_dispatch_src(u_int proto, uintptr_t source, struct mbuf *m)
  978 {
  979 #ifdef NETISR_LOCKING
  980         struct rm_priotracker tracker;
  981 #endif
  982         struct netisr_workstream *nwsp;
  983         struct netisr_proto *npp;
  984         struct netisr_work *npwp;
  985         int dosignal, error;
  986         u_int cpuid, dispatch_policy;
  987 
  988         KASSERT(proto < NETISR_MAXPROT,
  989             ("%s: invalid proto %u", __func__, proto));
  990 #ifdef NETISR_LOCKING
  991         NETISR_RLOCK(&tracker);
  992 #endif
  993         npp = &netisr_proto[proto];
  994         KASSERT(npp->np_handler != NULL, ("%s: invalid proto %u", __func__,
  995             proto));
  996 
  997         dispatch_policy = netisr_get_dispatch(npp);
  998         if (dispatch_policy == NETISR_DISPATCH_DEFERRED)
  999                 return (netisr_queue_src(proto, source, m));
 1000 
 1001         /*
 1002          * If direct dispatch is forced, then unconditionally dispatch
 1003          * without a formal CPU selection.  Borrow the current CPU's stats,
 1004          * even if there's no worker on it.  In this case we don't update
 1005          * nws_flags because all netisr processing will be source ordered due
 1006          * to always being forced to directly dispatch.
 1007          */
 1008         if (dispatch_policy == NETISR_DISPATCH_DIRECT) {
 1009                 nwsp = DPCPU_PTR(nws);
 1010                 npwp = &nwsp->nws_work[proto];
 1011                 npwp->nw_dispatched++;
 1012                 npwp->nw_handled++;
 1013                 netisr_proto[proto].np_handler(m);
 1014                 error = 0;
 1015                 goto out_unlock;
 1016         }
 1017 
 1018         KASSERT(dispatch_policy == NETISR_DISPATCH_HYBRID,
 1019             ("%s: unknown dispatch policy (%u)", __func__, dispatch_policy));
 1020 
 1021         /*
 1022          * Otherwise, we execute in a hybrid mode where we will try to direct
 1023          * dispatch if we're on the right CPU and the netisr worker isn't
 1024          * already running.
 1025          */
 1026         sched_pin();
 1027         m = netisr_select_cpuid(&netisr_proto[proto], NETISR_DISPATCH_HYBRID,
 1028             source, m, &cpuid);
 1029         if (m == NULL) {
 1030                 error = ENOBUFS;
 1031                 goto out_unpin;
 1032         }
 1033         KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__, cpuid));
 1034         if (cpuid != curcpu)
 1035                 goto queue_fallback;
 1036         nwsp = DPCPU_PTR(nws);
 1037         npwp = &nwsp->nws_work[proto];
 1038 
 1039         /*-
 1040          * We are willing to direct dispatch only if three conditions hold:
 1041          *
 1042          * (1) The netisr worker isn't already running,
 1043          * (2) Another thread isn't already directly dispatching, and
 1044          * (3) The netisr hasn't already been woken up.
 1045          */
 1046         NWS_LOCK(nwsp);
 1047         if (nwsp->nws_flags & (NWS_RUNNING | NWS_DISPATCHING | NWS_SCHEDULED)) {
 1048                 error = netisr_queue_workstream(nwsp, proto, npwp, m,
 1049                     &dosignal);
 1050                 NWS_UNLOCK(nwsp);
 1051                 if (dosignal)
 1052                         NWS_SIGNAL(nwsp);
 1053                 goto out_unpin;
 1054         }
 1055 
 1056         /*
 1057          * The current thread is now effectively the netisr worker, so set
 1058          * the dispatching flag to prevent concurrent processing of the
 1059          * stream from another thread (even the netisr worker), which could
 1060          * otherwise lead to effective misordering of the stream.
 1061          */
 1062         nwsp->nws_flags |= NWS_DISPATCHING;
 1063         NWS_UNLOCK(nwsp);
 1064         netisr_proto[proto].np_handler(m);
 1065         NWS_LOCK(nwsp);
 1066         nwsp->nws_flags &= ~NWS_DISPATCHING;
 1067         npwp->nw_handled++;
 1068         npwp->nw_hybrid_dispatched++;
 1069 
 1070         /*
 1071          * If other work was enqueued by another thread while we were direct
 1072          * dispatching, we need to signal the netisr worker to do that work.
 1073          * In the future, we might want to do some of that work in the
 1074          * current thread, rather than trigger further context switches.  If
 1075          * so, we'll want to establish a reasonable bound on the work done in
 1076          * the "borrowed" context.
 1077          */
 1078         if (nwsp->nws_pendingbits != 0) {
 1079                 nwsp->nws_flags |= NWS_SCHEDULED;
 1080                 dosignal = 1;
 1081         } else
 1082                 dosignal = 0;
 1083         NWS_UNLOCK(nwsp);
 1084         if (dosignal)
 1085                 NWS_SIGNAL(nwsp);
 1086         error = 0;
 1087         goto out_unpin;
 1088 
 1089 queue_fallback:
 1090         error = netisr_queue_internal(proto, m, cpuid);
 1091 out_unpin:
 1092         sched_unpin();
 1093 out_unlock:
 1094 #ifdef NETISR_LOCKING
 1095         NETISR_RUNLOCK(&tracker);
 1096 #endif
 1097         return (error);
 1098 }
 1099 
 1100 int
 1101 netisr_dispatch(u_int proto, struct mbuf *m)
 1102 {
 1103 
 1104         return (netisr_dispatch_src(proto, 0, m));
 1105 }
 1106 
 1107 #ifdef DEVICE_POLLING
 1108 /*
 1109  * Kernel polling borrows a netisr thread to run interface polling in; this
 1110  * function allows kernel polling to request that the netisr thread be
 1111  * scheduled even if no packets are pending for protocols.
 1112  */
 1113 void
 1114 netisr_sched_poll(void)
 1115 {
 1116         struct netisr_workstream *nwsp;
 1117 
 1118         nwsp = DPCPU_ID_PTR(nws_array[0], nws);
 1119         NWS_SIGNAL(nwsp);
 1120 }
 1121 #endif
 1122 
 1123 static void
 1124 netisr_start_swi(u_int cpuid, struct pcpu *pc)
 1125 {
 1126         char swiname[12];
 1127         struct netisr_workstream *nwsp;
 1128         int error;
 1129 
 1130         KASSERT(!CPU_ABSENT(cpuid), ("%s: CPU %u absent", __func__, cpuid));
 1131 
 1132         nwsp = DPCPU_ID_PTR(cpuid, nws);
 1133         mtx_init(&nwsp->nws_mtx, "netisr_mtx", NULL, MTX_DEF);
 1134         nwsp->nws_cpu = cpuid;
 1135         snprintf(swiname, sizeof(swiname), "netisr %u", cpuid);
 1136         error = swi_add(&nwsp->nws_intr_event, swiname, swi_net, nwsp,
 1137             SWI_NET, INTR_MPSAFE, &nwsp->nws_swi_cookie);
 1138         if (error)
 1139                 panic("%s: swi_add %d", __func__, error);
 1140         pc->pc_netisr = nwsp->nws_intr_event;
 1141         if (netisr_bindthreads) {
 1142                 error = intr_event_bind(nwsp->nws_intr_event, cpuid);
 1143                 if (error != 0)
 1144                         printf("%s: cpu %u: intr_event_bind: %d", __func__,
 1145                             cpuid, error);
 1146         }
 1147         NETISR_WLOCK();
 1148         nws_array[nws_count] = nwsp->nws_cpu;
 1149         nws_count++;
 1150         NETISR_WUNLOCK();
 1151 }
 1152 
 1153 /*
 1154  * Initialize the netisr subsystem.  We rely on BSS and static initialization
 1155  * of most fields in global data structures.
 1156  *
 1157  * Start a worker thread for the boot CPU so that we can support network
 1158  * traffic immediately in case the network stack is used before additional
 1159  * CPUs are started (for example, diskless boot).
 1160  */
 1161 static void
 1162 netisr_init(void *arg)
 1163 {
 1164         char tmp[NETISR_DISPATCH_POLICY_MAXSTR];
 1165         u_int dispatch_policy;
 1166         int error;
 1167 
 1168         KASSERT(curcpu == 0, ("%s: not on CPU 0", __func__));
 1169 
 1170         NETISR_LOCK_INIT();
 1171         if (netisr_maxthreads < 1)
 1172                 netisr_maxthreads = 1;
 1173         if (netisr_maxthreads > mp_ncpus) {
 1174                 printf("netisr_init: forcing maxthreads from %d to %d\n",
 1175                     netisr_maxthreads, mp_ncpus);
 1176                 netisr_maxthreads = mp_ncpus;
 1177         }
 1178         if (netisr_defaultqlimit > netisr_maxqlimit) {
 1179                 printf("netisr_init: forcing defaultqlimit from %d to %d\n",
 1180                     netisr_defaultqlimit, netisr_maxqlimit);
 1181                 netisr_defaultqlimit = netisr_maxqlimit;
 1182         }
 1183 #ifdef DEVICE_POLLING
 1184         /*
 1185          * The device polling code is not yet aware of how to deal with
 1186          * multiple netisr threads, so for the time being compiling in device
 1187          * polling disables parallel netisr workers.
 1188          */
 1189         if (netisr_maxthreads != 1 || netisr_bindthreads != 0) {
 1190                 printf("netisr_init: forcing maxthreads to 1 and "
 1191                     "bindthreads to 0 for device polling\n");
 1192                 netisr_maxthreads = 1;
 1193                 netisr_bindthreads = 0;
 1194         }
 1195 #endif
 1196 
 1197         if (TUNABLE_STR_FETCH("net.isr.dispatch", tmp, sizeof(tmp))) {
 1198                 error = netisr_dispatch_policy_from_str(tmp,
 1199                     &dispatch_policy);
 1200                 if (error == 0 && dispatch_policy == NETISR_DISPATCH_DEFAULT)
 1201                         error = EINVAL;
 1202                 if (error == 0) {
 1203                         netisr_dispatch_policy = dispatch_policy;
 1204                         netisr_dispatch_policy_compat();
 1205                 } else
 1206                         printf(
 1207                             "%s: invalid dispatch policy %s, using default\n",
 1208                             __func__, tmp);
 1209         }
 1210 
 1211         netisr_start_swi(curcpu, pcpu_find(curcpu));
 1212 }
 1213 SYSINIT(netisr_init, SI_SUB_SOFTINTR, SI_ORDER_FIRST, netisr_init, NULL);
 1214 
 1215 /*
 1216  * Start worker threads for additional CPUs.  No attempt to gracefully handle
 1217  * work reassignment, we don't yet support dynamic reconfiguration.
 1218  */
 1219 static void
 1220 netisr_start(void *arg)
 1221 {
 1222         struct pcpu *pc;
 1223 
 1224         STAILQ_FOREACH(pc, &cpuhead, pc_allcpu) {
 1225                 if (nws_count >= netisr_maxthreads)
 1226                         break;
 1227                 /* XXXRW: Is skipping absent CPUs still required here? */
 1228                 if (CPU_ABSENT(pc->pc_cpuid))
 1229                         continue;
 1230                 /* Worker will already be present for boot CPU. */
 1231                 if (pc->pc_netisr != NULL)
 1232                         continue;
 1233                 netisr_start_swi(pc->pc_cpuid, pc);
 1234         }
 1235 }
 1236 SYSINIT(netisr_start, SI_SUB_SMP, SI_ORDER_MIDDLE, netisr_start, NULL);
 1237 
 1238 /*
 1239  * Sysctl monitoring for netisr: query a list of registered protocols.
 1240  */
 1241 static int
 1242 sysctl_netisr_proto(SYSCTL_HANDLER_ARGS)
 1243 {
 1244         struct rm_priotracker tracker;
 1245         struct sysctl_netisr_proto *snpp, *snp_array;
 1246         struct netisr_proto *npp;
 1247         u_int counter, proto;
 1248         int error;
 1249 
 1250         if (req->newptr != NULL)
 1251                 return (EINVAL);
 1252         snp_array = malloc(sizeof(*snp_array) * NETISR_MAXPROT, M_TEMP,
 1253             M_ZERO | M_WAITOK);
 1254         counter = 0;
 1255         NETISR_RLOCK(&tracker);
 1256         for (proto = 0; proto < NETISR_MAXPROT; proto++) {
 1257                 npp = &netisr_proto[proto];
 1258                 if (npp->np_name == NULL)
 1259                         continue;
 1260                 snpp = &snp_array[counter];
 1261                 snpp->snp_version = sizeof(*snpp);
 1262                 strlcpy(snpp->snp_name, npp->np_name, NETISR_NAMEMAXLEN);
 1263                 snpp->snp_proto = proto;
 1264                 snpp->snp_qlimit = npp->np_qlimit;
 1265                 snpp->snp_policy = npp->np_policy;
 1266                 snpp->snp_dispatch = npp->np_dispatch;
 1267                 if (npp->np_m2flow != NULL)
 1268                         snpp->snp_flags |= NETISR_SNP_FLAGS_M2FLOW;
 1269                 if (npp->np_m2cpuid != NULL)
 1270                         snpp->snp_flags |= NETISR_SNP_FLAGS_M2CPUID;
 1271                 if (npp->np_drainedcpu != NULL)
 1272                         snpp->snp_flags |= NETISR_SNP_FLAGS_DRAINEDCPU;
 1273                 counter++;
 1274         }
 1275         NETISR_RUNLOCK(&tracker);
 1276         KASSERT(counter <= NETISR_MAXPROT,
 1277             ("sysctl_netisr_proto: counter too big (%d)", counter));
 1278         error = SYSCTL_OUT(req, snp_array, sizeof(*snp_array) * counter);
 1279         free(snp_array, M_TEMP);
 1280         return (error);
 1281 }
 1282 
 1283 SYSCTL_PROC(_net_isr, OID_AUTO, proto,
 1284     CTLFLAG_RD|CTLTYPE_STRUCT|CTLFLAG_MPSAFE, 0, 0, sysctl_netisr_proto,
 1285     "S,sysctl_netisr_proto",
 1286     "Return list of protocols registered with netisr");
 1287 
 1288 /*
 1289  * Sysctl monitoring for netisr: query a list of workstreams.
 1290  */
 1291 static int
 1292 sysctl_netisr_workstream(SYSCTL_HANDLER_ARGS)
 1293 {
 1294         struct rm_priotracker tracker;
 1295         struct sysctl_netisr_workstream *snwsp, *snws_array;
 1296         struct netisr_workstream *nwsp;
 1297         u_int counter, cpuid;
 1298         int error;
 1299 
 1300         if (req->newptr != NULL)
 1301                 return (EINVAL);
 1302         snws_array = malloc(sizeof(*snws_array) * MAXCPU, M_TEMP,
 1303             M_ZERO | M_WAITOK);
 1304         counter = 0;
 1305         NETISR_RLOCK(&tracker);
 1306         CPU_FOREACH(cpuid) {
 1307                 nwsp = DPCPU_ID_PTR(cpuid, nws);
 1308                 if (nwsp->nws_intr_event == NULL)
 1309                         continue;
 1310                 NWS_LOCK(nwsp);
 1311                 snwsp = &snws_array[counter];
 1312                 snwsp->snws_version = sizeof(*snwsp);
 1313 
 1314                 /*
 1315                  * For now, we equate workstream IDs and CPU IDs in the
 1316                  * kernel, but expose them independently to userspace in case
 1317                  * that assumption changes in the future.
 1318                  */
 1319                 snwsp->snws_wsid = cpuid;
 1320                 snwsp->snws_cpu = cpuid;
 1321                 if (nwsp->nws_intr_event != NULL)
 1322                         snwsp->snws_flags |= NETISR_SNWS_FLAGS_INTR;
 1323                 NWS_UNLOCK(nwsp);
 1324                 counter++;
 1325         }
 1326         NETISR_RUNLOCK(&tracker);
 1327         KASSERT(counter <= MAXCPU,
 1328             ("sysctl_netisr_workstream: counter too big (%d)", counter));
 1329         error = SYSCTL_OUT(req, snws_array, sizeof(*snws_array) * counter);
 1330         free(snws_array, M_TEMP);
 1331         return (error);
 1332 }
 1333 
 1334 SYSCTL_PROC(_net_isr, OID_AUTO, workstream,
 1335     CTLFLAG_RD|CTLTYPE_STRUCT|CTLFLAG_MPSAFE, 0, 0, sysctl_netisr_workstream,
 1336     "S,sysctl_netisr_workstream",
 1337     "Return list of workstreams implemented by netisr");
 1338 
 1339 /*
 1340  * Sysctl monitoring for netisr: query per-protocol data across all
 1341  * workstreams.
 1342  */
 1343 static int
 1344 sysctl_netisr_work(SYSCTL_HANDLER_ARGS)
 1345 {
 1346         struct rm_priotracker tracker;
 1347         struct sysctl_netisr_work *snwp, *snw_array;
 1348         struct netisr_workstream *nwsp;
 1349         struct netisr_proto *npp;
 1350         struct netisr_work *nwp;
 1351         u_int counter, cpuid, proto;
 1352         int error;
 1353 
 1354         if (req->newptr != NULL)
 1355                 return (EINVAL);
 1356         snw_array = malloc(sizeof(*snw_array) * MAXCPU * NETISR_MAXPROT,
 1357             M_TEMP, M_ZERO | M_WAITOK);
 1358         counter = 0;
 1359         NETISR_RLOCK(&tracker);
 1360         CPU_FOREACH(cpuid) {
 1361                 nwsp = DPCPU_ID_PTR(cpuid, nws);
 1362                 if (nwsp->nws_intr_event == NULL)
 1363                         continue;
 1364                 NWS_LOCK(nwsp);
 1365                 for (proto = 0; proto < NETISR_MAXPROT; proto++) {
 1366                         npp = &netisr_proto[proto];
 1367                         if (npp->np_name == NULL)
 1368                                 continue;
 1369                         nwp = &nwsp->nws_work[proto];
 1370                         snwp = &snw_array[counter];
 1371                         snwp->snw_version = sizeof(*snwp);
 1372                         snwp->snw_wsid = cpuid;         /* See comment above. */
 1373                         snwp->snw_proto = proto;
 1374                         snwp->snw_len = nwp->nw_len;
 1375                         snwp->snw_watermark = nwp->nw_watermark;
 1376                         snwp->snw_dispatched = nwp->nw_dispatched;
 1377                         snwp->snw_hybrid_dispatched =
 1378                             nwp->nw_hybrid_dispatched;
 1379                         snwp->snw_qdrops = nwp->nw_qdrops;
 1380                         snwp->snw_queued = nwp->nw_queued;
 1381                         snwp->snw_handled = nwp->nw_handled;
 1382                         counter++;
 1383                 }
 1384                 NWS_UNLOCK(nwsp);
 1385         }
 1386         KASSERT(counter <= MAXCPU * NETISR_MAXPROT,
 1387             ("sysctl_netisr_work: counter too big (%d)", counter));
 1388         NETISR_RUNLOCK(&tracker);
 1389         error = SYSCTL_OUT(req, snw_array, sizeof(*snw_array) * counter);
 1390         free(snw_array, M_TEMP);
 1391         return (error);
 1392 }
 1393 
 1394 SYSCTL_PROC(_net_isr, OID_AUTO, work,
 1395     CTLFLAG_RD|CTLTYPE_STRUCT|CTLFLAG_MPSAFE, 0, 0, sysctl_netisr_work,
 1396     "S,sysctl_netisr_work",
 1397     "Return list of per-workstream, per-protocol work in netisr");
 1398 
 1399 #ifdef DDB
 1400 DB_SHOW_COMMAND(netisr, db_show_netisr)
 1401 {
 1402         struct netisr_workstream *nwsp;
 1403         struct netisr_work *nwp;
 1404         int first, proto;
 1405         u_int cpuid;
 1406 
 1407         db_printf("%3s %6s %5s %5s %5s %8s %8s %8s %8s\n", "CPU", "Proto",
 1408             "Len", "WMark", "Max", "Disp", "HDisp", "Drop", "Queue");
 1409         CPU_FOREACH(cpuid) {
 1410                 nwsp = DPCPU_ID_PTR(cpuid, nws);
 1411                 if (nwsp->nws_intr_event == NULL)
 1412                         continue;
 1413                 first = 1;
 1414                 for (proto = 0; proto < NETISR_MAXPROT; proto++) {
 1415                         if (netisr_proto[proto].np_handler == NULL)
 1416                                 continue;
 1417                         nwp = &nwsp->nws_work[proto];
 1418                         if (first) {
 1419                                 db_printf("%3d ", cpuid);
 1420                                 first = 0;
 1421                         } else
 1422                                 db_printf("%3s ", "");
 1423                         db_printf(
 1424                             "%6s %5d %5d %5d %8ju %8ju %8ju %8ju\n",
 1425                             netisr_proto[proto].np_name, nwp->nw_len,
 1426                             nwp->nw_watermark, nwp->nw_qlimit,
 1427                             nwp->nw_dispatched, nwp->nw_hybrid_dispatched,
 1428                             nwp->nw_qdrops, nwp->nw_queued);
 1429                 }
 1430         }
 1431 }
 1432 #endif

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