Merge branch 'core/softlockup-for-linus' of git://git.kernel.org/pub/scm/linux/kernel...
[linux-2.6] / drivers / infiniband / hw / ipath / ipath_verbs_mcast.c
1 /*
2  * Copyright (c) 2006, 2007 QLogic Corporation. All rights reserved.
3  * Copyright (c) 2005, 2006 PathScale, Inc. All rights reserved.
4  *
5  * This software is available to you under a choice of one of two
6  * licenses.  You may choose to be licensed under the terms of the GNU
7  * General Public License (GPL) Version 2, available from the file
8  * COPYING in the main directory of this source tree, or the
9  * OpenIB.org BSD license below:
10  *
11  *     Redistribution and use in source and binary forms, with or
12  *     without modification, are permitted provided that the following
13  *     conditions are met:
14  *
15  *      - Redistributions of source code must retain the above
16  *        copyright notice, this list of conditions and the following
17  *        disclaimer.
18  *
19  *      - Redistributions in binary form must reproduce the above
20  *        copyright notice, this list of conditions and the following
21  *        disclaimer in the documentation and/or other materials
22  *        provided with the distribution.
23  *
24  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
28  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
29  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
30  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
31  * SOFTWARE.
32  */
33
34 #include <linux/rculist.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         mcast->n_attached = 0;
96
97 bail:
98         return mcast;
99 }
100
101 static void ipath_mcast_free(struct ipath_mcast *mcast)
102 {
103         struct ipath_mcast_qp *p, *tmp;
104
105         list_for_each_entry_safe(p, tmp, &mcast->qp_list, list)
106                 ipath_mcast_qp_free(p);
107
108         kfree(mcast);
109 }
110
111 /**
112  * ipath_mcast_find - search the global table for the given multicast GID
113  * @mgid: the multicast GID to search for
114  *
115  * Returns NULL if not found.
116  *
117  * The caller is responsible for decrementing the reference count if found.
118  */
119 struct ipath_mcast *ipath_mcast_find(union ib_gid *mgid)
120 {
121         struct rb_node *n;
122         unsigned long flags;
123         struct ipath_mcast *mcast;
124
125         spin_lock_irqsave(&mcast_lock, flags);
126         n = mcast_tree.rb_node;
127         while (n) {
128                 int ret;
129
130                 mcast = rb_entry(n, struct ipath_mcast, rb_node);
131
132                 ret = memcmp(mgid->raw, mcast->mgid.raw,
133                              sizeof(union ib_gid));
134                 if (ret < 0)
135                         n = n->rb_left;
136                 else if (ret > 0)
137                         n = n->rb_right;
138                 else {
139                         atomic_inc(&mcast->refcount);
140                         spin_unlock_irqrestore(&mcast_lock, flags);
141                         goto bail;
142                 }
143         }
144         spin_unlock_irqrestore(&mcast_lock, flags);
145
146         mcast = NULL;
147
148 bail:
149         return mcast;
150 }
151
152 /**
153  * ipath_mcast_add - insert mcast GID into table and attach QP struct
154  * @mcast: the mcast GID table
155  * @mqp: the QP to attach
156  *
157  * Return zero if both were added.  Return EEXIST if the GID was already in
158  * the table but the QP was added.  Return ESRCH if the QP was already
159  * attached and neither structure was added.
160  */
161 static int ipath_mcast_add(struct ipath_ibdev *dev,
162                            struct ipath_mcast *mcast,
163                            struct ipath_mcast_qp *mqp)
164 {
165         struct rb_node **n = &mcast_tree.rb_node;
166         struct rb_node *pn = NULL;
167         int ret;
168
169         spin_lock_irq(&mcast_lock);
170
171         while (*n) {
172                 struct ipath_mcast *tmcast;
173                 struct ipath_mcast_qp *p;
174
175                 pn = *n;
176                 tmcast = rb_entry(pn, struct ipath_mcast, rb_node);
177
178                 ret = memcmp(mcast->mgid.raw, tmcast->mgid.raw,
179                              sizeof(union ib_gid));
180                 if (ret < 0) {
181                         n = &pn->rb_left;
182                         continue;
183                 }
184                 if (ret > 0) {
185                         n = &pn->rb_right;
186                         continue;
187                 }
188
189                 /* Search the QP list to see if this is already there. */
190                 list_for_each_entry_rcu(p, &tmcast->qp_list, list) {
191                         if (p->qp == mqp->qp) {
192                                 ret = ESRCH;
193                                 goto bail;
194                         }
195                 }
196                 if (tmcast->n_attached == ib_ipath_max_mcast_qp_attached) {
197                         ret = ENOMEM;
198                         goto bail;
199                 }
200
201                 tmcast->n_attached++;
202
203                 list_add_tail_rcu(&mqp->list, &tmcast->qp_list);
204                 ret = EEXIST;
205                 goto bail;
206         }
207
208         spin_lock(&dev->n_mcast_grps_lock);
209         if (dev->n_mcast_grps_allocated == ib_ipath_max_mcast_grps) {
210                 spin_unlock(&dev->n_mcast_grps_lock);
211                 ret = ENOMEM;
212                 goto bail;
213         }
214
215         dev->n_mcast_grps_allocated++;
216         spin_unlock(&dev->n_mcast_grps_lock);
217
218         mcast->n_attached++;
219
220         list_add_tail_rcu(&mqp->list, &mcast->qp_list);
221
222         atomic_inc(&mcast->refcount);
223         rb_link_node(&mcast->rb_node, pn, n);
224         rb_insert_color(&mcast->rb_node, &mcast_tree);
225
226         ret = 0;
227
228 bail:
229         spin_unlock_irq(&mcast_lock);
230
231         return ret;
232 }
233
234 int ipath_multicast_attach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
235 {
236         struct ipath_qp *qp = to_iqp(ibqp);
237         struct ipath_ibdev *dev = to_idev(ibqp->device);
238         struct ipath_mcast *mcast;
239         struct ipath_mcast_qp *mqp;
240         int ret;
241
242         /*
243          * Allocate data structures since its better to do this outside of
244          * spin locks and it will most likely be needed.
245          */
246         mcast = ipath_mcast_alloc(gid);
247         if (mcast == NULL) {
248                 ret = -ENOMEM;
249                 goto bail;
250         }
251         mqp = ipath_mcast_qp_alloc(qp);
252         if (mqp == NULL) {
253                 ipath_mcast_free(mcast);
254                 ret = -ENOMEM;
255                 goto bail;
256         }
257         switch (ipath_mcast_add(dev, mcast, mqp)) {
258         case ESRCH:
259                 /* Neither was used: can't attach the same QP twice. */
260                 ipath_mcast_qp_free(mqp);
261                 ipath_mcast_free(mcast);
262                 ret = -EINVAL;
263                 goto bail;
264         case EEXIST:            /* The mcast wasn't used */
265                 ipath_mcast_free(mcast);
266                 break;
267         case ENOMEM:
268                 /* Exceeded the maximum number of mcast groups. */
269                 ipath_mcast_qp_free(mqp);
270                 ipath_mcast_free(mcast);
271                 ret = -ENOMEM;
272                 goto bail;
273         default:
274                 break;
275         }
276
277         ret = 0;
278
279 bail:
280         return ret;
281 }
282
283 int ipath_multicast_detach(struct ib_qp *ibqp, union ib_gid *gid, u16 lid)
284 {
285         struct ipath_qp *qp = to_iqp(ibqp);
286         struct ipath_ibdev *dev = to_idev(ibqp->device);
287         struct ipath_mcast *mcast = NULL;
288         struct ipath_mcast_qp *p, *tmp;
289         struct rb_node *n;
290         int last = 0;
291         int ret;
292
293         spin_lock_irq(&mcast_lock);
294
295         /* Find the GID in the mcast table. */
296         n = mcast_tree.rb_node;
297         while (1) {
298                 if (n == NULL) {
299                         spin_unlock_irq(&mcast_lock);
300                         ret = -EINVAL;
301                         goto bail;
302                 }
303
304                 mcast = rb_entry(n, struct ipath_mcast, rb_node);
305                 ret = memcmp(gid->raw, mcast->mgid.raw,
306                              sizeof(union ib_gid));
307                 if (ret < 0)
308                         n = n->rb_left;
309                 else if (ret > 0)
310                         n = n->rb_right;
311                 else
312                         break;
313         }
314
315         /* Search the QP list. */
316         list_for_each_entry_safe(p, tmp, &mcast->qp_list, list) {
317                 if (p->qp != qp)
318                         continue;
319                 /*
320                  * We found it, so remove it, but don't poison the forward
321                  * link until we are sure there are no list walkers.
322                  */
323                 list_del_rcu(&p->list);
324                 mcast->n_attached--;
325
326                 /* If this was the last attached QP, remove the GID too. */
327                 if (list_empty(&mcast->qp_list)) {
328                         rb_erase(&mcast->rb_node, &mcast_tree);
329                         last = 1;
330                 }
331                 break;
332         }
333
334         spin_unlock_irq(&mcast_lock);
335
336         if (p) {
337                 /*
338                  * Wait for any list walkers to finish before freeing the
339                  * list element.
340                  */
341                 wait_event(mcast->wait, atomic_read(&mcast->refcount) <= 1);
342                 ipath_mcast_qp_free(p);
343         }
344         if (last) {
345                 atomic_dec(&mcast->refcount);
346                 wait_event(mcast->wait, !atomic_read(&mcast->refcount));
347                 ipath_mcast_free(mcast);
348                 spin_lock_irq(&dev->n_mcast_grps_lock);
349                 dev->n_mcast_grps_allocated--;
350                 spin_unlock_irq(&dev->n_mcast_grps_lock);
351         }
352
353         ret = 0;
354
355 bail:
356         return ret;
357 }
358
359 int ipath_mcast_tree_empty(void)
360 {
361         return mcast_tree.rb_node == NULL;
362 }