sys/kern/kern_khelp.c

   1 /*-
   2  * Copyright (c) 2010,2013 Lawrence Stewart <lstewart@freebsd.org>
   3  * Copyright (c) 2010 The FreeBSD Foundation
   4  * All rights reserved.
   5  *
   6  * This software was developed by Lawrence Stewart while studying at the Centre
   7  * for Advanced Internet Architectures, Swinburne University of Technology,
   8  * made possible in part by grants from the FreeBSD Foundation and Cisco
   9  * University Research Program Fund at Community Foundation Silicon Valley.
  10  *
  11  * Portions of this software were developed at the Centre for Advanced
  12  * Internet Architectures, Swinburne University of Technology, Melbourne,
  13  * Australia by Lawrence Stewart under sponsorship from the FreeBSD Foundation.
  14  *
  15  * Redistribution and use in source and binary forms, with or without
  16  * modification, are permitted provided that the following conditions
  17  * are met:
  18  * 1. Redistributions of source code must retain the above copyright
  19  *    notice, this list of conditions and the following disclaimer.
  20  * 2. Redistributions in binary form must reproduce the above copyright
  21  *    notice, this list of conditions and the following disclaimer in the
  22  *    documentation and/or other materials provided with the distribution.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
  25  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  28  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  29  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  30  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  31  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  32  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  33  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  34  * SUCH DAMAGE.
  35  */
  36
  37 #include <sys/cdefs.h>
  38 __FBSDID("$FreeBSD$");
  39
  40 #include <sys/param.h>
  41 #include <sys/kernel.h>
  42 #include <sys/hhook.h>
  43 #include <sys/khelp.h>
  44 #include <sys/lock.h>
  45 #include <sys/malloc.h>
  46 #include <sys/module.h>
  47 #include <sys/module_khelp.h>
  48 #include <sys/osd.h>
  49 #include <sys/queue.h>
  50 #include <sys/refcount.h>
  51 #include <sys/rwlock.h>
  52 #include <sys/systm.h>
  53
  54 static struct rwlock khelp_list_lock;
  55 RW_SYSINIT(khelplistlock, &khelp_list_lock, "helper list lock");
  56
  57 static TAILQ_HEAD(helper_head, helper) helpers = TAILQ_HEAD_INITIALIZER(helpers);
  58
  59 /* Private function prototypes. */
  60 static inline void khelp_remove_osd(struct helper *h, struct osd *hosd);
  61 void khelp_new_hhook_registered(struct hhook_head *hhh, uint32_t flags);
  62
  63 #define KHELP_LIST_WLOCK() rw_wlock(&khelp_list_lock)
  64 #define KHELP_LIST_WUNLOCK() rw_wunlock(&khelp_list_lock)
  65 #define KHELP_LIST_RLOCK() rw_rlock(&khelp_list_lock)
  66 #define KHELP_LIST_RUNLOCK() rw_runlock(&khelp_list_lock)
  67 #define KHELP_LIST_LOCK_ASSERT() rw_assert(&khelp_list_lock, RA_LOCKED)
  68
  69 int
  70 khelp_register_helper(struct helper *h)
  71 {
  72         struct helper *tmph;
  73         int error, i, inserted;
  74
  75         error = inserted = 0;
  76         refcount_init(&h->h_refcount, 0);
  77         h->h_id = osd_register(OSD_KHELP, NULL, NULL);
  78
  79         /* It's only safe to add the hooks after osd_register(). */
  80         for (i = 0; i < h->h_nhooks && !error; i++) {
  81                 /* We don't require the module to assign hook_helper. */
  82                 h->h_hooks[i].hook_helper = h;
  83                 error = hhook_add_hook_lookup(&h->h_hooks[i], HHOOK_WAITOK);
  84                 if (error)
  85                         printf("%s: \"%s\" khelp module unable to "
  86                             "hook type %d id %d due to error %d\n", __func__,
  87                             h->h_name, h->h_hooks[i].hook_type,
  88                             h->h_hooks[i].hook_id, error);
  89         }
  90
  91         if (error) {
  92                 for (i--; i >= 0; i--)
  93                         hhook_remove_hook_lookup(&h->h_hooks[i]);
  94                 osd_deregister(OSD_KHELP, h->h_id);
  95         } else {
  96                 KHELP_LIST_WLOCK();
  97                 /*
  98                  * Keep list of helpers sorted in descending h_id order. Due to
  99                  * the way osd_set() works, a sorted list ensures
 100                  * khelp_init_osd() will operate with improved efficiency.
 101                  */
 102                 TAILQ_FOREACH(tmph, &helpers, h_next) {
 103                         if (tmph->h_id < h->h_id) {
 104                                 TAILQ_INSERT_BEFORE(tmph, h, h_next);
 105                                 inserted = 1;
 106                                 break;
 107                         }
 108                 }
 109
 110                 if (!inserted)
 111                         TAILQ_INSERT_TAIL(&helpers, h, h_next);
 112                 KHELP_LIST_WUNLOCK();
 113         }
 114
 115         return (error);
 116 }
 117
 118 int
 119 khelp_deregister_helper(struct helper *h)
 120 {
 121         struct helper *tmph;
 122         int error, i;
 123
 124         KHELP_LIST_WLOCK();
 125         if (h->h_refcount > 0)
 126                 error = EBUSY;
 127         else {
 128                 error = ENOENT;
 129                 TAILQ_FOREACH(tmph, &helpers, h_next) {
 130                         if (tmph == h) {
 131                                 TAILQ_REMOVE(&helpers, h, h_next);
 132                                 error = 0;
 133                                 break;
 134                         }
 135                 }
 136         }
 137         KHELP_LIST_WUNLOCK();
 138
 139         if (!error) {
 140                 for (i = 0; i < h->h_nhooks; i++)
 141                         hhook_remove_hook_lookup(&h->h_hooks[i]);
 142                 osd_deregister(OSD_KHELP, h->h_id);
 143         }
 144
 145         return (error);
 146 }
 147
 148 int
 149 khelp_init_osd(uint32_t classes, struct osd *hosd)
 150 {
 151         struct helper *h;
 152         void *hdata;
 153         int error;
 154
 155         KASSERT(hosd != NULL, ("struct osd not initialised!"));
 156
 157         error = 0;
 158
 159         KHELP_LIST_RLOCK();
 160         TAILQ_FOREACH(h, &helpers, h_next) {
 161                 /* If helper is correct class and needs to store OSD... */
 162                 if (h->h_classes & classes && h->h_flags & HELPER_NEEDS_OSD) {
 163                         hdata = uma_zalloc(h->h_zone, M_NOWAIT);
 164                         if (hdata == NULL) {
 165                                 error = ENOMEM;
 166                                 break;
 167                         }
 168                         osd_set(OSD_KHELP, hosd, h->h_id, hdata);
 169                         refcount_acquire(&h->h_refcount);
 170                 }
 171         }
 172
 173         if (error) {
 174                 /* Delete OSD that was assigned prior to the error. */
 175                 TAILQ_FOREACH(h, &helpers, h_next) {
 176                         if (h->h_classes & classes)
 177                                 khelp_remove_osd(h, hosd);
 178                 }
 179         }
 180         KHELP_LIST_RUNLOCK();
 181
 182         return (error);
 183 }
 184
 185 int
 186 khelp_destroy_osd(struct osd *hosd)
 187 {
 188         struct helper *h;
 189         int error;
 190
 191         KASSERT(hosd != NULL, ("struct osd not initialised!"));
 192
 193         error = 0;
 194
 195         KHELP_LIST_RLOCK();
 196         /*
 197          * Clean up all khelp related OSD.
 198          *
 199          * XXXLAS: Would be nice to use something like osd_exit() here but it
 200          * doesn't have the right semantics for this purpose.
 201          */
 202         TAILQ_FOREACH(h, &helpers, h_next)
 203                 khelp_remove_osd(h, hosd);
 204         KHELP_LIST_RUNLOCK();
 205
 206         return (error);
 207 }
 208
 209 static inline void
 210 khelp_remove_osd(struct helper *h, struct osd *hosd)
 211 {
 212         void *hdata;
 213
 214         if (h->h_flags & HELPER_NEEDS_OSD) {
 215                 /*
 216                  * If the current helper uses OSD and calling osd_get()
 217                  * on the helper's h_id returns non-NULL, the helper has
 218                  * OSD attached to 'hosd' which needs to be cleaned up.
 219                  */
 220                 hdata = osd_get(OSD_KHELP, hosd, h->h_id);
 221                 if (hdata != NULL) {
 222                         uma_zfree(h->h_zone, hdata);
 223                         osd_del(OSD_KHELP, hosd, h->h_id);
 224                         refcount_release(&h->h_refcount);
 225                 }
 226         }
 227 }
 228
 229 void *
 230 khelp_get_osd(struct osd *hosd, int32_t id)
 231 {
 232
 233         return (osd_get(OSD_KHELP, hosd, id));
 234 }
 235
 236 int32_t
 237 khelp_get_id(char *hname)
 238 {
 239         struct helper *h;
 240         int32_t id;
 241
 242         id = -1;
 243
 244         KHELP_LIST_RLOCK();
 245         TAILQ_FOREACH(h, &helpers, h_next) {
 246                 if (strncmp(h->h_name, hname, HELPER_NAME_MAXLEN) == 0) {
 247                         id = h->h_id;
 248                         break;
 249                 }
 250         }
 251         KHELP_LIST_RUNLOCK();
 252
 253         return (id);
 254 }
 255
 256 int
 257 khelp_add_hhook(struct hookinfo *hki, uint32_t flags)
 258 {
 259         int error;
 260
 261         /*
 262          * XXXLAS: Should probably include the functionality to update the
 263          * helper's h_hooks struct member.
 264          */
 265         error = hhook_add_hook_lookup(hki, flags);
 266
 267         return (error);
 268 }
 269
 270 int
 271 khelp_remove_hhook(struct hookinfo *hki)
 272 {
 273         int error;
 274
 275         /*
 276          * XXXLAS: Should probably include the functionality to update the
 277          * helper's h_hooks struct member.
 278          */
 279         error = hhook_remove_hook_lookup(hki);
 280
 281         return (error);
 282 }
 283
 284 /*
 285  * Private KPI between hhook and khelp that allows khelp modules to insert hook
 286  * functions into hhook points which register after the modules were loaded.
 287  */
 288 void
 289 khelp_new_hhook_registered(struct hhook_head *hhh, uint32_t flags)
 290 {
 291         struct helper *h;
 292         int error, i;
 293
 294         KHELP_LIST_RLOCK();
 295         TAILQ_FOREACH(h, &helpers, h_next) {
 296                 for (i = 0; i < h->h_nhooks; i++) {
 297                         if (hhh->hhh_type != h->h_hooks[i].hook_type ||
 298                             hhh->hhh_id != h->h_hooks[i].hook_id)
 299                                 continue;
 300                         error = hhook_add_hook(hhh, &h->h_hooks[i], flags);
 301                         if (error) {
 302                                 printf("%s: \"%s\" khelp module unable to "
 303                                     "hook type %d id %d due to error %d\n",
 304                                     __func__, h->h_name,
 305                                     h->h_hooks[i].hook_type,
 306                                     h->h_hooks[i].hook_id, error);
 307                                 error = 0;
 308                         }
 309                 }
 310         }
 311         KHELP_LIST_RUNLOCK();
 312 }
 313
 314 int
 315 khelp_modevent(module_t mod, int event_type, void *data)
 316 {
 317         struct khelp_modevent_data *kmd;
 318         int error;
 319
 320         kmd = (struct khelp_modevent_data *)data;
 321         error = 0;
 322
 323         switch(event_type) {
 324         case MOD_LOAD:
 325                 if (kmd->helper->h_flags & HELPER_NEEDS_OSD) {
 326                         if (kmd->uma_zsize <= 0) {
 327                                 printf("Use KHELP_DECLARE_MOD_UMA() instead!\n");
 328                                 error = EDOOFUS;
 329                                 break;
 330                         }
 331                         kmd->helper->h_zone = uma_zcreate(kmd->name,
 332                             kmd->uma_zsize, kmd->umactor, kmd->umadtor, NULL,
 333                             NULL, 0, 0);
 334                         if (kmd->helper->h_zone == NULL) {
 335                                 error = ENOMEM;
 336                                 break;
 337                         }
 338                 }
 339                 strlcpy(kmd->helper->h_name, kmd->name, HELPER_NAME_MAXLEN);
 340                 kmd->helper->h_hooks = kmd->hooks;
 341                 kmd->helper->h_nhooks = kmd->nhooks;
 342                 if (kmd->helper->mod_init != NULL)
 343                         error = kmd->helper->mod_init();
 344                 if (!error)
 345                         error = khelp_register_helper(kmd->helper);
 346                 break;
 347
 348         case MOD_QUIESCE:
 349         case MOD_SHUTDOWN:
 350         case MOD_UNLOAD:
 351                 error = khelp_deregister_helper(kmd->helper);
 352                 if (!error) {
 353                         if (kmd->helper->h_flags & HELPER_NEEDS_OSD)
 354                                 uma_zdestroy(kmd->helper->h_zone);
 355                         if (kmd->helper->mod_destroy != NULL)
 356                                 kmd->helper->mod_destroy();
 357                 } else if (error == ENOENT)
 358                         /* Do nothing and allow unload if helper not in list. */
 359                         error = 0;
 360                 else if (error == EBUSY)
 361                         printf("Khelp module \"%s\" can't unload until its "
 362                             "refcount drops from %d to 0.\n", kmd->name,
 363                             kmd->helper->h_refcount);
 364                 break;
 365
 366         default:
 367                 error = EINVAL;
 368                 break;
 369         }
 370
 371         return (error);
 372 }