RDS: Fix BUG_ONs to not fire when in a tasklet
[linux-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
36 #include "rds.h"
37 #include "rdma.h"
38 #include "ib.h"
39
40
41 /*
42  * This is stored as mr->r_trans_private.
43  */
44 struct rds_ib_mr {
45         struct rds_ib_device    *device;
46         struct rds_ib_mr_pool   *pool;
47         struct ib_fmr           *fmr;
48         struct list_head        list;
49         unsigned int            remap_count;
50
51         struct scatterlist      *sg;
52         unsigned int            sg_len;
53         u64                     *dma;
54         int                     sg_dma_len;
55 };
56
57 /*
58  * Our own little FMR pool
59  */
60 struct rds_ib_mr_pool {
61         struct mutex            flush_lock;             /* serialize fmr invalidate */
62         struct work_struct      flush_worker;           /* flush worker */
63
64         spinlock_t              list_lock;              /* protect variables below */
65         atomic_t                item_count;             /* total # of MRs */
66         atomic_t                dirty_count;            /* # dirty of MRs */
67         struct list_head        drop_list;              /* MRs that have reached their max_maps limit */
68         struct list_head        free_list;              /* unused MRs */
69         struct list_head        clean_list;             /* unused & unamapped MRs */
70         atomic_t                free_pinned;            /* memory pinned by free MRs */
71         unsigned long           max_items;
72         unsigned long           max_items_soft;
73         unsigned long           max_free_pinned;
74         struct ib_fmr_attr      fmr_attr;
75 };
76
77 static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all);
78 static void rds_ib_teardown_mr(struct rds_ib_mr *ibmr);
79 static void rds_ib_mr_pool_flush_worker(struct work_struct *work);
80
81 static struct rds_ib_device *rds_ib_get_device(__be32 ipaddr)
82 {
83         struct rds_ib_device *rds_ibdev;
84         struct rds_ib_ipaddr *i_ipaddr;
85
86         list_for_each_entry(rds_ibdev, &rds_ib_devices, list) {
87                 spin_lock_irq(&rds_ibdev->spinlock);
88                 list_for_each_entry(i_ipaddr, &rds_ibdev->ipaddr_list, list) {
89                         if (i_ipaddr->ipaddr == ipaddr) {
90                                 spin_unlock_irq(&rds_ibdev->spinlock);
91                                 return rds_ibdev;
92                         }
93                 }
94                 spin_unlock_irq(&rds_ibdev->spinlock);
95         }
96
97         return NULL;
98 }
99
100 static int rds_ib_add_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
101 {
102         struct rds_ib_ipaddr *i_ipaddr;
103
104         i_ipaddr = kmalloc(sizeof *i_ipaddr, GFP_KERNEL);
105         if (!i_ipaddr)
106                 return -ENOMEM;
107
108         i_ipaddr->ipaddr = ipaddr;
109
110         spin_lock_irq(&rds_ibdev->spinlock);
111         list_add_tail(&i_ipaddr->list, &rds_ibdev->ipaddr_list);
112         spin_unlock_irq(&rds_ibdev->spinlock);
113
114         return 0;
115 }
116
117 static void rds_ib_remove_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
118 {
119         struct rds_ib_ipaddr *i_ipaddr, *next;
120
121         spin_lock_irq(&rds_ibdev->spinlock);
122         list_for_each_entry_safe(i_ipaddr, next, &rds_ibdev->ipaddr_list, list) {
123                 if (i_ipaddr->ipaddr == ipaddr) {
124                         list_del(&i_ipaddr->list);
125                         kfree(i_ipaddr);
126                         break;
127                 }
128         }
129         spin_unlock_irq(&rds_ibdev->spinlock);
130 }
131
132 int rds_ib_update_ipaddr(struct rds_ib_device *rds_ibdev, __be32 ipaddr)
133 {
134         struct rds_ib_device *rds_ibdev_old;
135
136         rds_ibdev_old = rds_ib_get_device(ipaddr);
137         if (rds_ibdev_old)
138                 rds_ib_remove_ipaddr(rds_ibdev_old, ipaddr);
139
140         return rds_ib_add_ipaddr(rds_ibdev, ipaddr);
141 }
142
143 void rds_ib_add_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
144 {
145         struct rds_ib_connection *ic = conn->c_transport_data;
146
147         /* conn was previously on the nodev_conns_list */
148         spin_lock_irq(&ib_nodev_conns_lock);
149         BUG_ON(list_empty(&ib_nodev_conns));
150         BUG_ON(list_empty(&ic->ib_node));
151         list_del(&ic->ib_node);
152
153         spin_lock_irq(&rds_ibdev->spinlock);
154         list_add_tail(&ic->ib_node, &rds_ibdev->conn_list);
155         spin_unlock_irq(&rds_ibdev->spinlock);
156         spin_unlock_irq(&ib_nodev_conns_lock);
157
158         ic->rds_ibdev = rds_ibdev;
159 }
160
161 void rds_ib_remove_conn(struct rds_ib_device *rds_ibdev, struct rds_connection *conn)
162 {
163         struct rds_ib_connection *ic = conn->c_transport_data;
164
165         /* place conn on nodev_conns_list */
166         spin_lock(&ib_nodev_conns_lock);
167
168         spin_lock_irq(&rds_ibdev->spinlock);
169         BUG_ON(list_empty(&ic->ib_node));
170         list_del(&ic->ib_node);
171         spin_unlock_irq(&rds_ibdev->spinlock);
172
173         list_add_tail(&ic->ib_node, &ib_nodev_conns);
174
175         spin_unlock(&ib_nodev_conns_lock);
176
177         ic->rds_ibdev = NULL;
178 }
179
180 void __rds_ib_destroy_conns(struct list_head *list, spinlock_t *list_lock)
181 {
182         struct rds_ib_connection *ic, *_ic;
183         LIST_HEAD(tmp_list);
184
185         /* avoid calling conn_destroy with irqs off */
186         spin_lock_irq(list_lock);
187         list_splice(list, &tmp_list);
188         INIT_LIST_HEAD(list);
189         spin_unlock_irq(list_lock);
190
191         list_for_each_entry_safe(ic, _ic, &tmp_list, ib_node)
192                 rds_conn_destroy(ic->conn);
193 }
194
195 struct rds_ib_mr_pool *rds_ib_create_mr_pool(struct rds_ib_device *rds_ibdev)
196 {
197         struct rds_ib_mr_pool *pool;
198
199         pool = kzalloc(sizeof(*pool), GFP_KERNEL);
200         if (!pool)
201                 return ERR_PTR(-ENOMEM);
202
203         INIT_LIST_HEAD(&pool->free_list);
204         INIT_LIST_HEAD(&pool->drop_list);
205         INIT_LIST_HEAD(&pool->clean_list);
206         mutex_init(&pool->flush_lock);
207         spin_lock_init(&pool->list_lock);
208         INIT_WORK(&pool->flush_worker, rds_ib_mr_pool_flush_worker);
209
210         pool->fmr_attr.max_pages = fmr_message_size;
211         pool->fmr_attr.max_maps = rds_ibdev->fmr_max_remaps;
212         pool->fmr_attr.page_shift = PAGE_SHIFT;
213         pool->max_free_pinned = rds_ibdev->max_fmrs * fmr_message_size / 4;
214
215         /* We never allow more than max_items MRs to be allocated.
216          * When we exceed more than max_items_soft, we start freeing
217          * items more aggressively.
218          * Make sure that max_items > max_items_soft > max_items / 2
219          */
220         pool->max_items_soft = rds_ibdev->max_fmrs * 3 / 4;
221         pool->max_items = rds_ibdev->max_fmrs;
222
223         return pool;
224 }
225
226 void rds_ib_get_mr_info(struct rds_ib_device *rds_ibdev, struct rds_info_rdma_connection *iinfo)
227 {
228         struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
229
230         iinfo->rdma_mr_max = pool->max_items;
231         iinfo->rdma_mr_size = pool->fmr_attr.max_pages;
232 }
233
234 void rds_ib_destroy_mr_pool(struct rds_ib_mr_pool *pool)
235 {
236         flush_workqueue(rds_wq);
237         rds_ib_flush_mr_pool(pool, 1);
238         WARN_ON(atomic_read(&pool->item_count));
239         WARN_ON(atomic_read(&pool->free_pinned));
240         kfree(pool);
241 }
242
243 static inline struct rds_ib_mr *rds_ib_reuse_fmr(struct rds_ib_mr_pool *pool)
244 {
245         struct rds_ib_mr *ibmr = NULL;
246         unsigned long flags;
247
248         spin_lock_irqsave(&pool->list_lock, flags);
249         if (!list_empty(&pool->clean_list)) {
250                 ibmr = list_entry(pool->clean_list.next, struct rds_ib_mr, list);
251                 list_del_init(&ibmr->list);
252         }
253         spin_unlock_irqrestore(&pool->list_lock, flags);
254
255         return ibmr;
256 }
257
258 static struct rds_ib_mr *rds_ib_alloc_fmr(struct rds_ib_device *rds_ibdev)
259 {
260         struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
261         struct rds_ib_mr *ibmr = NULL;
262         int err = 0, iter = 0;
263
264         while (1) {
265                 ibmr = rds_ib_reuse_fmr(pool);
266                 if (ibmr)
267                         return ibmr;
268
269                 /* No clean MRs - now we have the choice of either
270                  * allocating a fresh MR up to the limit imposed by the
271                  * driver, or flush any dirty unused MRs.
272                  * We try to avoid stalling in the send path if possible,
273                  * so we allocate as long as we're allowed to.
274                  *
275                  * We're fussy with enforcing the FMR limit, though. If the driver
276                  * tells us we can't use more than N fmrs, we shouldn't start
277                  * arguing with it */
278                 if (atomic_inc_return(&pool->item_count) <= pool->max_items)
279                         break;
280
281                 atomic_dec(&pool->item_count);
282
283                 if (++iter > 2) {
284                         rds_ib_stats_inc(s_ib_rdma_mr_pool_depleted);
285                         return ERR_PTR(-EAGAIN);
286                 }
287
288                 /* We do have some empty MRs. Flush them out. */
289                 rds_ib_stats_inc(s_ib_rdma_mr_pool_wait);
290                 rds_ib_flush_mr_pool(pool, 0);
291         }
292
293         ibmr = kzalloc(sizeof(*ibmr), GFP_KERNEL);
294         if (!ibmr) {
295                 err = -ENOMEM;
296                 goto out_no_cigar;
297         }
298
299         ibmr->fmr = ib_alloc_fmr(rds_ibdev->pd,
300                         (IB_ACCESS_LOCAL_WRITE |
301                          IB_ACCESS_REMOTE_READ |
302                          IB_ACCESS_REMOTE_WRITE),
303                         &pool->fmr_attr);
304         if (IS_ERR(ibmr->fmr)) {
305                 err = PTR_ERR(ibmr->fmr);
306                 ibmr->fmr = NULL;
307                 printk(KERN_WARNING "RDS/IB: ib_alloc_fmr failed (err=%d)\n", err);
308                 goto out_no_cigar;
309         }
310
311         rds_ib_stats_inc(s_ib_rdma_mr_alloc);
312         return ibmr;
313
314 out_no_cigar:
315         if (ibmr) {
316                 if (ibmr->fmr)
317                         ib_dealloc_fmr(ibmr->fmr);
318                 kfree(ibmr);
319         }
320         atomic_dec(&pool->item_count);
321         return ERR_PTR(err);
322 }
323
324 static int rds_ib_map_fmr(struct rds_ib_device *rds_ibdev, struct rds_ib_mr *ibmr,
325                struct scatterlist *sg, unsigned int nents)
326 {
327         struct ib_device *dev = rds_ibdev->dev;
328         struct scatterlist *scat = sg;
329         u64 io_addr = 0;
330         u64 *dma_pages;
331         u32 len;
332         int page_cnt, sg_dma_len;
333         int i, j;
334         int ret;
335
336         sg_dma_len = ib_dma_map_sg(dev, sg, nents,
337                                  DMA_BIDIRECTIONAL);
338         if (unlikely(!sg_dma_len)) {
339                 printk(KERN_WARNING "RDS/IB: dma_map_sg failed!\n");
340                 return -EBUSY;
341         }
342
343         len = 0;
344         page_cnt = 0;
345
346         for (i = 0; i < sg_dma_len; ++i) {
347                 unsigned int dma_len = ib_sg_dma_len(dev, &scat[i]);
348                 u64 dma_addr = ib_sg_dma_address(dev, &scat[i]);
349
350                 if (dma_addr & ~PAGE_MASK) {
351                         if (i > 0)
352                                 return -EINVAL;
353                         else
354                                 ++page_cnt;
355                 }
356                 if ((dma_addr + dma_len) & ~PAGE_MASK) {
357                         if (i < sg_dma_len - 1)
358                                 return -EINVAL;
359                         else
360                                 ++page_cnt;
361                 }
362
363                 len += dma_len;
364         }
365
366         page_cnt += len >> PAGE_SHIFT;
367         if (page_cnt > fmr_message_size)
368                 return -EINVAL;
369
370         dma_pages = kmalloc(sizeof(u64) * page_cnt, GFP_ATOMIC);
371         if (!dma_pages)
372                 return -ENOMEM;
373
374         page_cnt = 0;
375         for (i = 0; i < sg_dma_len; ++i) {
376                 unsigned int dma_len = ib_sg_dma_len(dev, &scat[i]);
377                 u64 dma_addr = ib_sg_dma_address(dev, &scat[i]);
378
379                 for (j = 0; j < dma_len; j += PAGE_SIZE)
380                         dma_pages[page_cnt++] =
381                                 (dma_addr & PAGE_MASK) + j;
382         }
383
384         ret = ib_map_phys_fmr(ibmr->fmr,
385                                    dma_pages, page_cnt, io_addr);
386         if (ret)
387                 goto out;
388
389         /* Success - we successfully remapped the MR, so we can
390          * safely tear down the old mapping. */
391         rds_ib_teardown_mr(ibmr);
392
393         ibmr->sg = scat;
394         ibmr->sg_len = nents;
395         ibmr->sg_dma_len = sg_dma_len;
396         ibmr->remap_count++;
397
398         rds_ib_stats_inc(s_ib_rdma_mr_used);
399         ret = 0;
400
401 out:
402         kfree(dma_pages);
403
404         return ret;
405 }
406
407 void rds_ib_sync_mr(void *trans_private, int direction)
408 {
409         struct rds_ib_mr *ibmr = trans_private;
410         struct rds_ib_device *rds_ibdev = ibmr->device;
411
412         switch (direction) {
413         case DMA_FROM_DEVICE:
414                 ib_dma_sync_sg_for_cpu(rds_ibdev->dev, ibmr->sg,
415                         ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
416                 break;
417         case DMA_TO_DEVICE:
418                 ib_dma_sync_sg_for_device(rds_ibdev->dev, ibmr->sg,
419                         ibmr->sg_dma_len, DMA_BIDIRECTIONAL);
420                 break;
421         }
422 }
423
424 static void __rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
425 {
426         struct rds_ib_device *rds_ibdev = ibmr->device;
427
428         if (ibmr->sg_dma_len) {
429                 ib_dma_unmap_sg(rds_ibdev->dev,
430                                 ibmr->sg, ibmr->sg_len,
431                                 DMA_BIDIRECTIONAL);
432                 ibmr->sg_dma_len = 0;
433         }
434
435         /* Release the s/g list */
436         if (ibmr->sg_len) {
437                 unsigned int i;
438
439                 for (i = 0; i < ibmr->sg_len; ++i) {
440                         struct page *page = sg_page(&ibmr->sg[i]);
441
442                         /* FIXME we need a way to tell a r/w MR
443                          * from a r/o MR */
444                         BUG_ON(irqs_disabled());
445                         set_page_dirty(page);
446                         put_page(page);
447                 }
448                 kfree(ibmr->sg);
449
450                 ibmr->sg = NULL;
451                 ibmr->sg_len = 0;
452         }
453 }
454
455 static void rds_ib_teardown_mr(struct rds_ib_mr *ibmr)
456 {
457         unsigned int pinned = ibmr->sg_len;
458
459         __rds_ib_teardown_mr(ibmr);
460         if (pinned) {
461                 struct rds_ib_device *rds_ibdev = ibmr->device;
462                 struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
463
464                 atomic_sub(pinned, &pool->free_pinned);
465         }
466 }
467
468 static inline unsigned int rds_ib_flush_goal(struct rds_ib_mr_pool *pool, int free_all)
469 {
470         unsigned int item_count;
471
472         item_count = atomic_read(&pool->item_count);
473         if (free_all)
474                 return item_count;
475
476         return 0;
477 }
478
479 /*
480  * Flush our pool of MRs.
481  * At a minimum, all currently unused MRs are unmapped.
482  * If the number of MRs allocated exceeds the limit, we also try
483  * to free as many MRs as needed to get back to this limit.
484  */
485 static int rds_ib_flush_mr_pool(struct rds_ib_mr_pool *pool, int free_all)
486 {
487         struct rds_ib_mr *ibmr, *next;
488         LIST_HEAD(unmap_list);
489         LIST_HEAD(fmr_list);
490         unsigned long unpinned = 0;
491         unsigned long flags;
492         unsigned int nfreed = 0, ncleaned = 0, free_goal;
493         int ret = 0;
494
495         rds_ib_stats_inc(s_ib_rdma_mr_pool_flush);
496
497         mutex_lock(&pool->flush_lock);
498
499         spin_lock_irqsave(&pool->list_lock, flags);
500         /* Get the list of all MRs to be dropped. Ordering matters -
501          * we want to put drop_list ahead of free_list. */
502         list_splice_init(&pool->free_list, &unmap_list);
503         list_splice_init(&pool->drop_list, &unmap_list);
504         if (free_all)
505                 list_splice_init(&pool->clean_list, &unmap_list);
506         spin_unlock_irqrestore(&pool->list_lock, flags);
507
508         free_goal = rds_ib_flush_goal(pool, free_all);
509
510         if (list_empty(&unmap_list))
511                 goto out;
512
513         /* String all ib_mr's onto one list and hand them to ib_unmap_fmr */
514         list_for_each_entry(ibmr, &unmap_list, list)
515                 list_add(&ibmr->fmr->list, &fmr_list);
516         ret = ib_unmap_fmr(&fmr_list);
517         if (ret)
518                 printk(KERN_WARNING "RDS/IB: ib_unmap_fmr failed (err=%d)\n", ret);
519
520         /* Now we can destroy the DMA mapping and unpin any pages */
521         list_for_each_entry_safe(ibmr, next, &unmap_list, list) {
522                 unpinned += ibmr->sg_len;
523                 __rds_ib_teardown_mr(ibmr);
524                 if (nfreed < free_goal || ibmr->remap_count >= pool->fmr_attr.max_maps) {
525                         rds_ib_stats_inc(s_ib_rdma_mr_free);
526                         list_del(&ibmr->list);
527                         ib_dealloc_fmr(ibmr->fmr);
528                         kfree(ibmr);
529                         nfreed++;
530                 }
531                 ncleaned++;
532         }
533
534         spin_lock_irqsave(&pool->list_lock, flags);
535         list_splice(&unmap_list, &pool->clean_list);
536         spin_unlock_irqrestore(&pool->list_lock, flags);
537
538         atomic_sub(unpinned, &pool->free_pinned);
539         atomic_sub(ncleaned, &pool->dirty_count);
540         atomic_sub(nfreed, &pool->item_count);
541
542 out:
543         mutex_unlock(&pool->flush_lock);
544         return ret;
545 }
546
547 static void rds_ib_mr_pool_flush_worker(struct work_struct *work)
548 {
549         struct rds_ib_mr_pool *pool = container_of(work, struct rds_ib_mr_pool, flush_worker);
550
551         rds_ib_flush_mr_pool(pool, 0);
552 }
553
554 void rds_ib_free_mr(void *trans_private, int invalidate)
555 {
556         struct rds_ib_mr *ibmr = trans_private;
557         struct rds_ib_device *rds_ibdev = ibmr->device;
558         struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
559         unsigned long flags;
560
561         rdsdebug("RDS/IB: free_mr nents %u\n", ibmr->sg_len);
562
563         /* Return it to the pool's free list */
564         spin_lock_irqsave(&pool->list_lock, flags);
565         if (ibmr->remap_count >= pool->fmr_attr.max_maps)
566                 list_add(&ibmr->list, &pool->drop_list);
567         else
568                 list_add(&ibmr->list, &pool->free_list);
569
570         atomic_add(ibmr->sg_len, &pool->free_pinned);
571         atomic_inc(&pool->dirty_count);
572         spin_unlock_irqrestore(&pool->list_lock, flags);
573
574         /* If we've pinned too many pages, request a flush */
575         if (atomic_read(&pool->free_pinned) >= pool->max_free_pinned ||
576             atomic_read(&pool->dirty_count) >= pool->max_items / 10)
577                 queue_work(rds_wq, &pool->flush_worker);
578
579         if (invalidate) {
580                 if (likely(!in_interrupt())) {
581                         rds_ib_flush_mr_pool(pool, 0);
582                 } else {
583                         /* We get here if the user created a MR marked
584                          * as use_once and invalidate at the same time. */
585                         queue_work(rds_wq, &pool->flush_worker);
586                 }
587         }
588 }
589
590 void rds_ib_flush_mrs(void)
591 {
592         struct rds_ib_device *rds_ibdev;
593
594         list_for_each_entry(rds_ibdev, &rds_ib_devices, list) {
595                 struct rds_ib_mr_pool *pool = rds_ibdev->mr_pool;
596
597                 if (pool)
598                         rds_ib_flush_mr_pool(pool, 0);
599         }
600 }
601
602 void *rds_ib_get_mr(struct scatterlist *sg, unsigned long nents,
603                     struct rds_sock *rs, u32 *key_ret)
604 {
605         struct rds_ib_device *rds_ibdev;
606         struct rds_ib_mr *ibmr = NULL;
607         int ret;
608
609         rds_ibdev = rds_ib_get_device(rs->rs_bound_addr);
610         if (!rds_ibdev) {
611                 ret = -ENODEV;
612                 goto out;
613         }
614
615         if (!rds_ibdev->mr_pool) {
616                 ret = -ENODEV;
617                 goto out;
618         }
619
620         ibmr = rds_ib_alloc_fmr(rds_ibdev);
621         if (IS_ERR(ibmr))
622                 return ibmr;
623
624         ret = rds_ib_map_fmr(rds_ibdev, ibmr, sg, nents);
625         if (ret == 0)
626                 *key_ret = ibmr->fmr->rkey;
627         else
628                 printk(KERN_WARNING "RDS/IB: map_fmr failed (errno=%d)\n", ret);
629
630         ibmr->device = rds_ibdev;
631
632  out:
633         if (ret) {
634                 if (ibmr)
635                         rds_ib_free_mr(ibmr, 0);
636                 ibmr = ERR_PTR(ret);
637         }
638         return ibmr;
639 }