spi: bcm-qspi: Fix use after free in bcm_qspi_probe() in error path
[sfrench/cifs-2.6.git] / net / rds / ib_rdma.c
1 /*
2  * Copyright (c) 2006 Oracle.  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/kernel.h>
34 #include <linux/slab.h>
35 #include <linux/rculist.h>
36 #include <linux/llist.h>
37
38 #include "rds_single_path.h"
39 #include "ib_mr.h"
40
41 struct workqueue_struct *rds_ib_mr_wq;
42
43 static DEFINE_PER_CPU(unsigned long, clean_list_grace);
44 #define CLEAN_LIST_BUSY_BIT 0
45
46 static struct rds_ib_device *rds_ib_get_device(__be32 ipaddr)
47 {
48         struct rds_ib_device *rds_ibdev;
49         struct rds_ib_ipaddr *i_ipaddr;
50
51         rcu_read_lock();
52         list_for_each_entry_rcu(rds_ibdev, &rds_ib_devices, list) {
53                 list_for_each_entry_rcu(i_ipaddr, &rds_ibdev->ipaddr_list, list) {
54                         if (i_ipaddr->ipaddr == ipaddr) {
55                                 refcount_inc(&rds_ibdev->refcount);
56                                 rcu_read_unlock();
57                                 return rds_ibdev;
58                         }
59                 }
60         }
61         rcu_read_unlock();
62
63         return NULL;
64 }
65
66 static int rds_ib_add_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
67 {
68         struct rds_ib_ipaddr *i_ipaddr;
69
70         i_ipaddr = kmalloc(sizeof *i_ipaddr, GFP_KERNEL);
71         if (!i_ipaddr)
72                 return -ENOMEM;
73
74         i_ipaddr->ipaddr = ipaddr;
75
76         spin_lock_irq(&rds_ibdev->spinlock);
77         list_add_tail_rcu(&i_ipaddr->list, &rds_ibdev->ipaddr_list);
78         spin_unlock_irq(&rds_ibdev->spinlock);
79
80         return 0;
81 }
82
83 static void rds_ib_remove_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
84 {
85         struct rds_ib_ipaddr *i_ipaddr;
86         struct rds_ib_ipaddr *to_free = NULL;
87
88
89         spin_lock_irq(&rds_ibdev->spinlock);
90         list_for_each_entry_rcu(i_ipaddr, &rds_ibdev->ipaddr_list, list) {
91                 if (i_ipaddr->ipaddr == ipaddr) {
92                         list_del_rcu(&i_ipaddr->list);
93                         to_free = i_ipaddr;
94                         break;
95                 }
96         }
97         spin_unlock_irq(&rds_ibdev->spinlock);
98
99         if (to_free)
100                 kfree_rcu(to_free, rcu);
101 }
102
103 int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
104 {
105         struct rds_ib_device *rds_ibdev_old;
106
107         rds_ibdev_old = rds_ib_get_device(ipaddr);
108         if (!rds_ibdev_old)
109                 return rds_ib_add_ipaddr(rds_ibdev, ipaddr);
110
111         if (rds_ibdev_old != rds_ibdev) {
112                 rds_ib_remove_ipaddr(rds_ibdev_old, ipaddr);
113                 rds_ib_dev_put(rds_ibdev_old);
114                 return rds_ib_add_ipaddr(rds_ibdev, ipaddr);
115         }
116         rds_ib_dev_put(rds_ibdev_old);
117
118         return 0;
119 }
120
121 void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
122 {
123         struct rds_ib_connection *ic = conn->c_transport_data;
124
125         /* conn was previously on the nodev_conns_list */
126         spin_lock_irq(&ib_nodev_conns_lock);
127         BUG_ON(list_empty(&ib_nodev_conns));
128         BUG_ON(list_empty(&ic->ib_node));
129         list_del(&ic->ib_node);
130
131         spin_lock(&rds_ibdev->spinlock);
132         list_add_tail(&ic->ib_node, &rds_ibdev->conn_list);
133         spin_unlock(&rds_ibdev->spinlock);
134         spin_unlock_irq(&ib_nodev_conns_lock);
135
136         ic->rds_ibdev = rds_ibdev;
137         refcount_inc(&rds_ibdev->refcount);
138 }
139
140 void rds_ib_remove_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
141 {
142         struct rds_ib_connection *ic = conn->c_transport_data;
143
144         /* place conn on nodev_conns_list */
145         spin_lock(&ib_nodev_conns_lock);
146
147         spin_lock_irq(&rds_ibdev->spinlock);
148         BUG_ON(list_empty(&ic->ib_node));
149         list_del(&ic->ib_node);
150         spin_unlock_irq(&rds_ibdev->spinlock);
151
152         list_add_tail(&ic->ib_node, &ib_nodev_conns);
153
154         spin_unlock(&ib_nodev_conns_lock);
155
156         ic->rds_ibdev = NULL;
157         rds_ib_dev_put(rds_ibdev);
158 }
159
160 void rds_ib_destroy_nodev_conns(void)
161 {
162         struct rds_ib_connection *ic, *_ic;
163         LIST_HEAD(tmp_list);
164
165         /* avoid calling conn_destroy with irqs off */
166         spin_lock_irq(&ib_nodev_conns_lock);
167         list_splice(&ib_nodev_conns, &tmp_list);
168         spin_unlock_irq(&ib_nodev_conns_lock);
169
170         list_for_each_entry_safe(ic, _ic, &tmp_list, ib_node)
171                 rds_conn_destroy(ic->conn);
172 }
173
174 void rds_ib_get_mr_info(struct rds_ib_device *rds_ibdev, struct rds_info_rdma_connection *iinfo)
175 {
176         struct rds_ib_mr_pool *pool_1m = rds_ibdev->mr_1m_pool;
177
178         iinfo->rdma_mr_max = pool_1m->max_items;
179         iinfo->rdma_mr_size = pool_1m->fmr_attr.max_pages;
180 }
181
182 struct rds_ib_mr *rds_ib_reuse_mr(struct rds_ib_mr_pool *pool)
183 {
184         struct rds_ib_mr *ibmr = NULL;
185         struct llist_node *ret;
186         unsigned long *flag;
187
188         preempt_disable();
189         flag = this_cpu_ptr(&clean_list_grace);
190         set_bit(CLEAN_LIST_BUSY_BIT, flag);
191         ret = llist_del_first(&pool->clean_list);
192         if (ret) {
193                 ibmr = llist_entry(ret, struct rds_ib_mr, llnode);
194                 if (pool->pool_type == RDS_IB_MR_8K_POOL)
195                         rds_ib_stats_inc(s_ib_rdma_mr_8k_reused);
196                 else
197                         rds_ib_stats_inc(s_ib_rdma_mr_1m_reused);
198         }
199
200         clear_bit(CLEAN_LIST_BUSY_BIT, flag);
201         preempt_enable();
202         return ibmr;
203 }
204
205 static inline void wait_clean_list_grace(void)
206 {
207         int cpu;
208         unsigned long *flag;
209
210         for_each_online_cpu(cpu) {
211                 flag = &per_cpu(clean_list_grace, cpu);
212                 while (test_bit(CLEAN_LIST_BUSY_BIT, flag))
213                         cpu_relax();
214         }
215 }
216
217 void rds_ib_sync_mr(void *trans_private, int direction)
218 {
219         struct rds_ib_mr *ibmr = trans_private;
220         struct rds_ib_device *rds_ibdev = ibmr->device;
221
222         switch (direction) {
223         case DMA_FROM_DEVICE:
224                 ib_dma_sync_sg_for_cpu(rds_ibdev->dev, ibmr->sg,
225                         ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
226                 break;
227         case DMA_TO_DEVICE:
228                 ib_dma_sync_sg_for_device(rds_ibdev->dev, ibmr->sg,
229                         ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
230                 break;
231         }
232 }
233
234 void __rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
235 {
236         struct rds_ib_device *rds_ibdev = ibmr->device;
237
238         if (ibmr->sg_dma_len) {
239                 ib_dma_unmap_sg(rds_ibdev->dev,
240                                 ibmr->sg, ibmr->sg_len,
241                                 DMA_BIDIRECTIONAL);
242                 ibmr->sg_dma_len = 0;
243         }
244
245         /* Release the s/g list */
246         if (ibmr->sg_len) {
247                 unsigned int i;
248
249                 for (i = 0; i < ibmr->sg_len; ++i) {
250                         struct page *page = sg_page(&ibmr->sg[i]);
251
252                         /* FIXME we need a way to tell a r/w MR
253                          * from a r/o MR */
254                         WARN_ON(!page->mapping && irqs_disabled());
255                         set_page_dirty(page);
256                         put_page(page);
257                 }
258                 kfree(ibmr->sg);
259
260                 ibmr->sg = NULL;
261                 ibmr->sg_len = 0;
262         }
263 }
264
265 void rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
266 {
267         unsigned int pinned = ibmr->sg_len;
268
269         __rds_ib_teardown_mr(ibmr);
270         if (pinned) {
271                 struct rds_ib_mr_pool *pool = ibmr->pool;
272
273                 atomic_sub(pinned, &pool->free_pinned);
274         }
275 }
276
277 static inline unsigned int rds_ib_flush_goal(struct rds_ib_mr_pool *pool, int free_all)
278 {
279         unsigned int item_count;
280
281         item_count = atomic_read(&pool->item_count);
282         if (free_all)
283                 return item_count;
284
285         return 0;
286 }
287
288 /*
289  * given an llist of mrs, put them all into the list_head for more processing
290  */
291 static unsigned int llist_append_to_list(struct llist_head *llist,
292                                          struct list_head *list)
293 {
294         struct rds_ib_mr *ibmr;
295         struct llist_node *node;
296         struct llist_node *next;
297         unsigned int count = 0;
298
299         node = llist_del_all(llist);
300         while (node) {
301                 next = node->next;
302                 ibmr = llist_entry(node, struct rds_ib_mr, llnode);
303                 list_add_tail(&ibmr->unmap_list, list);
304                 node = next;
305                 count++;
306         }
307         return count;
308 }
309
310 /*
311  * this takes a list head of mrs and turns it into linked llist nodes
312  * of clusters.  Each cluster has linked llist nodes of
313  * MR_CLUSTER_SIZE mrs that are ready for reuse.
314  */
315 static void list_to_llist_nodes(struct rds_ib_mr_pool *pool,
316                                 struct list_head *list,
317                                 struct llist_node **nodes_head,
318                                 struct llist_node **nodes_tail)
319 {
320         struct rds_ib_mr *ibmr;
321         struct llist_node *cur = NULL;
322         struct llist_node **next = nodes_head;
323
324         list_for_each_entry(ibmr, list, unmap_list) {
325                 cur = &ibmr->llnode;
326                 *next = cur;
327                 next = &cur->next;
328         }
329         *next = NULL;
330         *nodes_tail = cur;
331 }
332
333 /*
334  * Flush our pool of MRs.
335  * At a minimum, all currently unused MRs are unmapped.
336  * If the number of MRs allocated exceeds the limit, we also try
337  * to free as many MRs as needed to get back to this limit.
338  */
339 int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool,
340                          int free_all, struct rds_ib_mr **ibmr_ret)
341 {
342         struct rds_ib_mr *ibmr;
343         struct llist_node *clean_nodes;
344         struct llist_node *clean_tail;
345         LIST_HEAD(unmap_list);
346         unsigned long unpinned = 0;
347         unsigned int nfreed = 0, dirty_to_clean = 0, free_goal;
348
349         if (pool->pool_type == RDS_IB_MR_8K_POOL)
350                 rds_ib_stats_inc(s_ib_rdma_mr_8k_pool_flush);
351         else
352                 rds_ib_stats_inc(s_ib_rdma_mr_1m_pool_flush);
353
354         if (ibmr_ret) {
355                 DEFINE_WAIT(wait);
356                 while (!mutex_trylock(&pool->flush_lock)) {
357                         ibmr = rds_ib_reuse_mr(pool);
358                         if (ibmr) {
359                                 *ibmr_ret = ibmr;
360                                 finish_wait(&pool->flush_wait, &wait);
361                                 goto out_nolock;
362                         }
363
364                         prepare_to_wait(&pool->flush_wait, &wait,
365                                         TASK_UNINTERRUPTIBLE);
366                         if (llist_empty(&pool->clean_list))
367                                 schedule();
368
369                         ibmr = rds_ib_reuse_mr(pool);
370                         if (ibmr) {
371                                 *ibmr_ret = ibmr;
372                                 finish_wait(&pool->flush_wait, &wait);
373                                 goto out_nolock;
374                         }
375                 }
376                 finish_wait(&pool->flush_wait, &wait);
377         } else
378                 mutex_lock(&pool->flush_lock);
379
380         if (ibmr_ret) {
381                 ibmr = rds_ib_reuse_mr(pool);
382                 if (ibmr) {
383                         *ibmr_ret = ibmr;
384                         goto out;
385                 }
386         }
387
388         /* Get the list of all MRs to be dropped. Ordering matters -
389          * we want to put drop_list ahead of free_list.
390          */
391         dirty_to_clean = llist_append_to_list(&pool->drop_list, &unmap_list);
392         dirty_to_clean += llist_append_to_list(&pool->free_list, &unmap_list);
393         if (free_all)
394                 llist_append_to_list(&pool->clean_list, &unmap_list);
395
396         free_goal = rds_ib_flush_goal(pool, free_all);
397
398         if (list_empty(&unmap_list))
399                 goto out;
400
401         if (pool->use_fastreg)
402                 rds_ib_unreg_frmr(&unmap_list, &nfreed, &unpinned, free_goal);
403         else
404                 rds_ib_unreg_fmr(&unmap_list, &nfreed, &unpinned, free_goal);
405
406         if (!list_empty(&unmap_list)) {
407                 /* we have to make sure that none of the things we're about
408                  * to put on the clean list would race with other cpus trying
409                  * to pull items off.  The llist would explode if we managed to
410                  * remove something from the clean list and then add it back again
411                  * while another CPU was spinning on that same item in llist_del_first.
412                  *
413                  * This is pretty unlikely, but just in case  wait for an llist grace period
414                  * here before adding anything back into the clean list.
415                  */
416                 wait_clean_list_grace();
417
418                 list_to_llist_nodes(pool, &unmap_list, &clean_nodes, &clean_tail);
419                 if (ibmr_ret)
420                         *ibmr_ret = llist_entry(clean_nodes, struct rds_ib_mr, llnode);
421
422                 /* more than one entry in llist nodes */
423                 if (clean_nodes->next)
424                         llist_add_batch(clean_nodes->next, clean_tail, &pool->clean_list);
425
426         }
427
428         atomic_sub(unpinned, &pool->free_pinned);
429         atomic_sub(dirty_to_clean, &pool->dirty_count);
430         atomic_sub(nfreed, &pool->item_count);
431
432 out:
433         mutex_unlock(&pool->flush_lock);
434         if (waitqueue_active(&pool->flush_wait))
435                 wake_up(&pool->flush_wait);
436 out_nolock:
437         return 0;
438 }
439
440 struct rds_ib_mr *rds_ib_try_reuse_ibmr(struct rds_ib_mr_pool *pool)
441 {
442         struct rds_ib_mr *ibmr = NULL;
443         int iter = 0;
444
445         if (atomic_read(&pool->dirty_count) >= pool->max_items_soft / 10)
446                 queue_delayed_work(rds_ib_mr_wq, &pool->flush_worker, 10);
447
448         while (1) {
449                 ibmr = rds_ib_reuse_mr(pool);
450                 if (ibmr)
451                         return ibmr;
452
453                 if (atomic_inc_return(&pool->item_count) <= pool->max_items)
454                         break;
455
456                 atomic_dec(&pool->item_count);
457
458                 if (++iter > 2) {
459                         if (pool->pool_type == RDS_IB_MR_8K_POOL)
460                                 rds_ib_stats_inc(s_ib_rdma_mr_8k_pool_depleted);
461                         else
462                                 rds_ib_stats_inc(s_ib_rdma_mr_1m_pool_depleted);
463                         return ERR_PTR(-EAGAIN);
464                 }
465
466                 /* We do have some empty MRs. Flush them out. */
467                 if (pool->pool_type == RDS_IB_MR_8K_POOL)
468                         rds_ib_stats_inc(s_ib_rdma_mr_8k_pool_wait);
469                 else
470                         rds_ib_stats_inc(s_ib_rdma_mr_1m_pool_wait);
471
472                 rds_ib_flush_mr_pool(pool, 0, &ibmr);
473                 if (ibmr)
474                         return ibmr;
475         }
476
477         return ibmr;
478 }
479
480 static void rds_ib_mr_pool_flush_worker(struct work_struct *work)
481 {
482         struct rds_ib_mr_pool *pool = container_of(work, struct rds_ib_mr_pool, flush_worker.work);
483
484         rds_ib_flush_mr_pool(pool, 0, NULL);
485 }
486
487 void rds_ib_free_mr(void *trans_private, int invalidate)
488 {
489         struct rds_ib_mr *ibmr = trans_private;
490         struct rds_ib_mr_pool *pool = ibmr->pool;
491         struct rds_ib_device *rds_ibdev = ibmr->device;
492
493         rdsdebug("RDS/IB: free_mr nents %u\n", ibmr->sg_len);
494
495         /* Return it to the pool's free list */
496         if (rds_ibdev->use_fastreg)
497                 rds_ib_free_frmr_list(ibmr);
498         else
499                 rds_ib_free_fmr_list(ibmr);
500
501         atomic_add(ibmr->sg_len, &pool->free_pinned);
502         atomic_inc(&pool->dirty_count);
503
504         /* If we've pinned too many pages, request a flush */
505         if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned ||
506             atomic_read(&pool->dirty_count) >= pool->max_items / 5)
507                 queue_delayed_work(rds_ib_mr_wq, &pool->flush_worker, 10);
508
509         if (invalidate) {
510                 if (likely(!in_interrupt())) {
511                         rds_ib_flush_mr_pool(pool, 0, NULL);
512                 } else {
513                         /* We get here if the user created a MR marked
514                          * as use_once and invalidate at the same time.
515                          */
516                         queue_delayed_work(rds_ib_mr_wq,
517                                            &pool->flush_worker, 10);
518                 }
519         }
520
521         rds_ib_dev_put(rds_ibdev);
522 }
523
524 void rds_ib_flush_mrs(void)
525 {
526         struct rds_ib_device *rds_ibdev;
527
528         down_read(&rds_ib_devices_lock);
529         list_for_each_entry(rds_ibdev, &rds_ib_devices, list) {
530                 if (rds_ibdev->mr_8k_pool)
531                         rds_ib_flush_mr_pool(rds_ibdev->mr_8k_pool, 0, NULL);
532
533                 if (rds_ibdev->mr_1m_pool)
534                         rds_ib_flush_mr_pool(rds_ibdev->mr_1m_pool, 0, NULL);
535         }
536         up_read(&rds_ib_devices_lock);
537 }
538
539 void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents,
540                     struct rds_sock *rs, u32 *key_ret)
541 {
542         struct rds_ib_device *rds_ibdev;
543         struct rds_ib_mr *ibmr = NULL;
544         struct rds_ib_connection *ic = rs->rs_conn->c_transport_data;
545         int ret;
546
547         rds_ibdev = rds_ib_get_device(rs->rs_bound_addr);
548         if (!rds_ibdev) {
549                 ret = -ENODEV;
550                 goto out;
551         }
552
553         if (!rds_ibdev->mr_8k_pool || !rds_ibdev->mr_1m_pool) {
554                 ret = -ENODEV;
555                 goto out;
556         }
557
558         if (rds_ibdev->use_fastreg)
559                 ibmr = rds_ib_reg_frmr(rds_ibdev, ic, sg, nents, key_ret);
560         else
561                 ibmr = rds_ib_reg_fmr(rds_ibdev, sg, nents, key_ret);
562         if (ibmr)
563                 rds_ibdev = NULL;
564
565  out:
566         if (!ibmr)
567                 pr_warn("RDS/IB: rds_ib_get_mr failed (errno=%d)\n", ret);
568
569         if (rds_ibdev)
570                 rds_ib_dev_put(rds_ibdev);
571
572         return ibmr;
573 }
574
575 void rds_ib_destroy_mr_pool(struct rds_ib_mr_pool *pool)
576 {
577         cancel_delayed_work_sync(&pool->flush_worker);
578         rds_ib_flush_mr_pool(pool, 1, NULL);
579         WARN_ON(atomic_read(&pool->item_count));
580         WARN_ON(atomic_read(&pool->free_pinned));
581         kfree(pool);
582 }
583
584 struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *rds_ibdev,
585                                              int pool_type)
586 {
587         struct rds_ib_mr_pool *pool;
588
589         pool = kzalloc(sizeof(*pool), GFP_KERNEL);
590         if (!pool)
591                 return ERR_PTR(-ENOMEM);
592
593         pool->pool_type = pool_type;
594         init_llist_head(&pool->free_list);
595         init_llist_head(&pool->drop_list);
596         init_llist_head(&pool->clean_list);
597         mutex_init(&pool->flush_lock);
598         init_waitqueue_head(&pool->flush_wait);
599         INIT_DELAYED_WORK(&pool->flush_worker, rds_ib_mr_pool_flush_worker);
600
601         if (pool_type == RDS_IB_MR_1M_POOL) {
602                 /* +1 allows for unaligned MRs */
603                 pool->fmr_attr.max_pages = RDS_MR_1M_MSG_SIZE + 1;
604                 pool->max_items = RDS_MR_1M_POOL_SIZE;
605         } else {
606                 /* pool_type == RDS_IB_MR_8K_POOL */
607                 pool->fmr_attr.max_pages = RDS_MR_8K_MSG_SIZE + 1;
608                 pool->max_items = RDS_MR_8K_POOL_SIZE;
609         }
610
611         pool->max_free_pinned = pool->max_items * pool->fmr_attr.max_pages / 4;
612         pool->fmr_attr.max_maps = rds_ibdev->fmr_max_remaps;
613         pool->fmr_attr.page_shift = PAGE_SHIFT;
614         pool->max_items_soft = rds_ibdev->max_mrs * 3 / 4;
615         pool->use_fastreg = rds_ibdev->use_fastreg;
616
617         return pool;
618 }
619
620 int rds_ib_mr_init(void)
621 {
622         rds_ib_mr_wq = alloc_workqueue("rds_mr_flushd", WQ_MEM_RECLAIM, 0);
623         if (!rds_ib_mr_wq)
624                 return -ENOMEM;
625         return 0;
626 }
627
628 /* By the time this is called all the IB devices should have been torn down and
629  * had their pools freed.  As each pool is freed its work struct is waited on,
630  * so the pool flushing work queue should be idle by the time we get here.
631  */
632 void rds_ib_mr_exit(void)
633 {
634         destroy_workqueue(rds_ib_mr_wq);
635 }