drivers/infiniband/hw/ipath/ipath_verbs_mcast.c

   1 /*
   2  * Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
   3  *
   4  * This software is available to you under a choice of one of two
   5  * licenses.  You may choose to be licensed under the terms of the GNU
   6  * General Public License (GPL) Version 2, available from the file
   7  * COPYING in the main directory of this source tree, or the
   8  * OpenIB.org BSD license below:
   9  *
  10  *     Redistribution and use in source and binary forms, with or
  11  *     without modification, are permitted provided that the following
  12  *     conditions are met:
  13  *
  14  *      - Redistributions of source code must retain the above
  15  *        copyright notice, this list of conditions and the following
  16  *        disclaimer.
  17  *
  18  *      - Redistributions in binary form must reproduce the above
  19  *        copyright notice, this list of conditions and the following
  20  *        disclaimer in the documentation and/or other materials
  21  *        provided with the distribution.
  22  *
  23  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30  * SOFTWARE.
  31  */
  32
  33 #include <linux/list.h>
  34 #include <linux/rcupdate.h>
  35
  36 #include "ipath_verbs.h"
  37
  38 /*
  39  * Global table of GID to attached QPs.
  40  * The table is global to all ipath devices since a send from one QP/device
  41  * needs to be locally routed to any locally attached QPs on the same
  42  * or different device.
  43  */
  44 static struct rb_root mcast_tree;
  45 static DEFINE_SPINLOCK(mcast_lock);
  46
  47 /**
  48  * ipath_mcast_qp_alloc - alloc a struct to link a QP to mcast GID struct
  49  * @qp: the QP to link
  50  */
  51 static struct ipath_mcast_qp *ipath_mcast_qp_alloc(struct ipath_qp *qp)
  52 {
  53         struct ipath_mcast_qp *mqp;
  54
  55         mqp = kmalloc(sizeof *mqp, GFP_KERNEL);
  56         if (!mqp)
  57                 goto bail;
  58
  59         mqp->qp = qp;
  60         atomic_inc(&qp->refcount);
  61
  62 bail:
  63         return mqp;
  64 }
  65
  66 static void ipath_mcast_qp_free(struct ipath_mcast_qp *mqp)
  67 {
  68         struct ipath_qp *qp = mqp->qp;
  69
  70         /* Notify ipath_destroy_qp() if it is waiting. */
  71         if (atomic_dec_and_test(&qp->refcount))
  72                 wake_up(&qp->wait);
  73
  74         kfree(mqp);
  75 }
  76
  77 /**
  78  * ipath_mcast_alloc - allocate the multicast GID structure
  79  * @mgid: the multicast GID
  80  *
  81  * A list of QPs will be attached to this structure.
  82  */
  83 static struct ipath_mcast *ipath_mcast_alloc(union ib_gid *mgid)
  84 {
  85         struct ipath_mcast *mcast;
  86
  87         mcast = kmalloc(sizeof *mcast, GFP_KERNEL);
  88         if (!mcast)
  89                 goto bail;
  90
  91         mcast->mgid = *mgid;
  92         INIT_LIST_HEAD(&mcast->qp_list);
  93         init_waitqueue_head(&mcast->wait);
  94         atomic_set(&mcast->refcount, 0);
  95
  96 bail:
  97         return mcast;
  98 }
  99
 100 static void ipath_mcast_free(struct ipath_mcast *mcast)
 101 {
 102         struct ipath_mcast_qp *p, *tmp;
 103
 104         list_for_each_entry_safe(p, tmp, &mcast->qp_list, list)
 105                 ipath_mcast_qp_free(p);
 106
 107         kfree(mcast);
 108 }
 109
 110 /**
 111  * ipath_mcast_find - search the global table for the given multicast GID
 112  * @mgid: the multicast GID to search for
 113  *
 114  * Returns NULL if not found.
 115  *
 116  * The caller is responsible for decrementing the reference count if found.
 117  */
 118 struct ipath_mcast *ipath_mcast_find(union ib_gid *mgid)
 119 {
 120         struct rb_node *n;
 121         unsigned long flags;
 122         struct ipath_mcast *mcast;
 123
 124         spin_lock_irqsave(&mcast_lock, flags);
 125         n = mcast_tree.rb_node;
 126         while (n) {
 127                 int ret;
 128
 129                 mcast = rb_entry(n, struct ipath_mcast, rb_node);
 130
 131                 ret = memcmp(mgid->raw, mcast->mgid.raw,
 132                              sizeof(union ib_gid));
 133                 if (ret < 0)
 134                         n = n->rb_left;
 135                 else if (ret > 0)
 136                         n = n->rb_right;
 137                 else {
 138                         atomic_inc(&mcast->refcount);
 139                         spin_unlock_irqrestore(&mcast_lock, flags);
 140                         goto bail;
 141                 }
 142         }
 143         spin_unlock_irqrestore(&mcast_lock, flags);
 144
 145         mcast = NULL;
 146
 147 bail:
 148         return mcast;
 149 }
 150
 151 /**
 152  * ipath_mcast_add - insert mcast GID into table and attach QP struct
 153  * @mcast: the mcast GID table
 154  * @mqp: the QP to attach
 155  *
 156  * Return zero if both were added.  Return EEXIST if the GID was already in
 157  * the table but the QP was added.  Return ESRCH if the QP was already
 158  * attached and neither structure was added.
 159  */
 160 static int ipath_mcast_add(struct ipath_mcast *mcast,
 161                            struct ipath_mcast_qp *mqp)
 162 {
 163         struct rb_node **n = &mcast_tree.rb_node;
 164         struct rb_node *pn = NULL;
 165         unsigned long flags;
 166         int ret;
 167
 168         spin_lock_irqsave(&mcast_lock, flags);
 169
 170         while (*n) {
 171                 struct ipath_mcast *tmcast;
 172                 struct ipath_mcast_qp *p;
 173
 174                 pn = *n;
 175                 tmcast = rb_entry(pn, struct ipath_mcast, rb_node);
 176
 177                 ret = memcmp(mcast->mgid.raw, tmcast->mgid.raw,
 178                              sizeof(union ib_gid));
 179                 if (ret < 0) {
 180                         n = &pn->rb_left;
 181                         continue;
 182                 }
 183                 if (ret > 0) {
 184                         n = &pn->rb_right;
 185                         continue;
 186                 }
 187
 188                 /* Search the QP list to see if this is already there. */
 189                 list_for_each_entry_rcu(p, &tmcast->qp_list, list) {
 190                         if (p->qp == mqp->qp) {
 191                                 spin_unlock_irqrestore(&mcast_lock, flags);
 192                                 ret = ESRCH;
 193                                 goto bail;
 194                         }
 195                 }
 196                 list_add_tail_rcu(&mqp->list, &tmcast->qp_list);
 197                 spin_unlock_irqrestore(&mcast_lock, flags);
 198                 ret = EEXIST;
 199                 goto bail;
 200         }
 201
 202         list_add_tail_rcu(&mqp->list, &mcast->qp_list);
 203
 204         atomic_inc(&mcast->refcount);
 205         rb_link_node(&mcast->rb_node, pn, n);
 206         rb_insert_color(&mcast->rb_node, &mcast_tree);
 207
 208         spin_unlock_irqrestore(&mcast_lock, flags);
 209
 210         ret = 0;
 211
 212 bail:
 213         return ret;
 214 }
 215
 216 int ipath_multicast_attach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
 217 {
 218         struct ipath_qp *qp = to_iqp(ibqp);
 219         struct ipath_mcast *mcast;
 220         struct ipath_mcast_qp *mqp;
 221         int ret;
 222
 223         /*
 224          * Allocate data structures since its better to do this outside of
 225          * spin locks and it will most likely be needed.
 226          */
 227         mcast = ipath_mcast_alloc(gid);
 228         if (mcast == NULL) {
 229                 ret = -ENOMEM;
 230                 goto bail;
 231         }
 232         mqp = ipath_mcast_qp_alloc(qp);
 233         if (mqp == NULL) {
 234                 ipath_mcast_free(mcast);
 235                 ret = -ENOMEM;
 236                 goto bail;
 237         }
 238         switch (ipath_mcast_add(mcast, mqp)) {
 239         case ESRCH:
 240                 /* Neither was used: can't attach the same QP twice. */
 241                 ipath_mcast_qp_free(mqp);
 242                 ipath_mcast_free(mcast);
 243                 ret = -EINVAL;
 244                 goto bail;
 245         case EEXIST:            /* The mcast wasn't used */
 246                 ipath_mcast_free(mcast);
 247                 break;
 248         default:
 249                 break;
 250         }
 251
 252         ret = 0;
 253
 254 bail:
 255         return ret;
 256 }
 257
 258 int ipath_multicast_detach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
 259 {
 260         struct ipath_qp *qp = to_iqp(ibqp);
 261         struct ipath_mcast *mcast = NULL;
 262         struct ipath_mcast_qp *p, *tmp;
 263         struct rb_node *n;
 264         unsigned long flags;
 265         int last = 0;
 266         int ret;
 267
 268         spin_lock_irqsave(&mcast_lock, flags);
 269
 270         /* Find the GID in the mcast table. */
 271         n = mcast_tree.rb_node;
 272         while (1) {
 273                 if (n == NULL) {
 274                         spin_unlock_irqrestore(&mcast_lock, flags);
 275                         ret = 0;
 276                         goto bail;
 277                 }
 278
 279                 mcast = rb_entry(n, struct ipath_mcast, rb_node);
 280                 ret = memcmp(gid->raw, mcast->mgid.raw,
 281                              sizeof(union ib_gid));
 282                 if (ret < 0)
 283                         n = n->rb_left;
 284                 else if (ret > 0)
 285                         n = n->rb_right;
 286                 else
 287                         break;
 288         }
 289
 290         /* Search the QP list. */
 291         list_for_each_entry_safe(p, tmp, &mcast->qp_list, list) {
 292                 if (p->qp != qp)
 293                         continue;
 294                 /*
 295                  * We found it, so remove it, but don't poison the forward
 296                  * link until we are sure there are no list walkers.
 297                  */
 298                 list_del_rcu(&p->list);
 299
 300                 /* If this was the last attached QP, remove the GID too. */
 301                 if (list_empty(&mcast->qp_list)) {
 302                         rb_erase(&mcast->rb_node, &mcast_tree);
 303                         last = 1;
 304                 }
 305                 break;
 306         }
 307
 308         spin_unlock_irqrestore(&mcast_lock, flags);
 309
 310         if (p) {
 311                 /*
 312                  * Wait for any list walkers to finish before freeing the
 313                  * list element.
 314                  */
 315                 wait_event(mcast->wait, atomic_read(&mcast->refcount) <= 1);
 316                 ipath_mcast_qp_free(p);
 317         }
 318         if (last) {
 319                 atomic_dec(&mcast->refcount);
 320                 wait_event(mcast->wait, !atomic_read(&mcast->refcount));
 321                 ipath_mcast_free(mcast);
 322         }
 323
 324         ret = 0;
 325
 326 bail:
 327         return ret;
 328 }
 329
 330 int ipath_mcast_tree_empty(void)
 331 {
 332         return mcast_tree.rb_node == NULL;
 333 }