blob: 595a952d4b17f069c60a457701d6e207f68e621b [file] [log] [blame]
Andy Grover7875e182009-02-24 15:30:26 +00001/*
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/highmem.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090034#include <linux/gfp.h>
Andy Grover7875e182009-02-24 15:30:26 +000035
36#include "rds.h"
37
38struct rds_page_remainder {
39 struct page *r_page;
40 unsigned long r_offset;
41};
42
Tejun Heob9bf3122009-06-24 15:13:47 +090043DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders);
Andy Grover7875e182009-02-24 15:30:26 +000044
45/*
46 * returns 0 on success or -errno on failure.
47 *
48 * We don't have to worry about flush_dcache_page() as this only works
49 * with private pages. If, say, we were to do directed receive to pinned
50 * user pages we'd have to worry more about cache coherence. (Though
51 * the flush_dcache_page() in get_user_pages() would probably be enough).
52 */
53int rds_page_copy_user(struct page *page, unsigned long offset,
54 void __user *ptr, unsigned long bytes,
55 int to_user)
56{
57 unsigned long ret;
58 void *addr;
59
60 if (to_user)
61 rds_stats_add(s_copy_to_user, bytes);
62 else
63 rds_stats_add(s_copy_from_user, bytes);
64
65 addr = kmap_atomic(page, KM_USER0);
66 if (to_user)
67 ret = __copy_to_user_inatomic(ptr, addr + offset, bytes);
68 else
69 ret = __copy_from_user_inatomic(addr + offset, ptr, bytes);
70 kunmap_atomic(addr, KM_USER0);
71
72 if (ret) {
73 addr = kmap(page);
74 if (to_user)
75 ret = copy_to_user(ptr, addr + offset, bytes);
76 else
77 ret = copy_from_user(addr + offset, ptr, bytes);
78 kunmap(page);
79 if (ret)
80 return -EFAULT;
81 }
82
83 return 0;
84}
Andy Grover616b7572009-08-21 12:28:32 +000085EXPORT_SYMBOL_GPL(rds_page_copy_user);
Andy Grover7875e182009-02-24 15:30:26 +000086
87/*
88 * Message allocation uses this to build up regions of a message.
89 *
90 * @bytes - the number of bytes needed.
91 * @gfp - the waiting behaviour of the allocation
92 *
93 * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to
94 * kmap the pages, etc.
95 *
96 * If @bytes is at least a full page then this just returns a page from
97 * alloc_page().
98 *
99 * If @bytes is a partial page then this stores the unused region of the
100 * page in a per-cpu structure. Future partial-page allocations may be
101 * satisfied from that cached region. This lets us waste less memory on
102 * small allocations with minimal complexity. It works because the transmit
103 * path passes read-only page regions down to devices. They hold a page
104 * reference until they are done with the region.
105 */
106int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
107 gfp_t gfp)
108{
109 struct rds_page_remainder *rem;
110 unsigned long flags;
111 struct page *page;
112 int ret;
113
114 gfp |= __GFP_HIGHMEM;
115
116 /* jump straight to allocation if we're trying for a huge page */
117 if (bytes >= PAGE_SIZE) {
118 page = alloc_page(gfp);
119 if (page == NULL) {
120 ret = -ENOMEM;
121 } else {
122 sg_set_page(scat, page, PAGE_SIZE, 0);
123 ret = 0;
124 }
125 goto out;
126 }
127
128 rem = &per_cpu(rds_page_remainders, get_cpu());
129 local_irq_save(flags);
130
131 while (1) {
132 /* avoid a tiny region getting stuck by tossing it */
133 if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) {
134 rds_stats_inc(s_page_remainder_miss);
135 __free_page(rem->r_page);
136 rem->r_page = NULL;
137 }
138
139 /* hand out a fragment from the cached page */
140 if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) {
141 sg_set_page(scat, rem->r_page, bytes, rem->r_offset);
142 get_page(sg_page(scat));
143
144 if (rem->r_offset != 0)
145 rds_stats_inc(s_page_remainder_hit);
146
147 rem->r_offset += bytes;
148 if (rem->r_offset == PAGE_SIZE) {
149 __free_page(rem->r_page);
150 rem->r_page = NULL;
151 }
152 ret = 0;
153 break;
154 }
155
156 /* alloc if there is nothing for us to use */
157 local_irq_restore(flags);
158 put_cpu();
159
160 page = alloc_page(gfp);
161
162 rem = &per_cpu(rds_page_remainders, get_cpu());
163 local_irq_save(flags);
164
165 if (page == NULL) {
166 ret = -ENOMEM;
167 break;
168 }
169
170 /* did someone race to fill the remainder before us? */
171 if (rem->r_page) {
172 __free_page(page);
173 continue;
174 }
175
176 /* otherwise install our page and loop around to alloc */
177 rem->r_page = page;
178 rem->r_offset = 0;
179 }
180
181 local_irq_restore(flags);
182 put_cpu();
183out:
184 rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
185 ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
186 ret ? 0 : scat->length);
187 return ret;
188}
189
190static int rds_page_remainder_cpu_notify(struct notifier_block *self,
191 unsigned long action, void *hcpu)
192{
193 struct rds_page_remainder *rem;
194 long cpu = (long)hcpu;
195
196 rem = &per_cpu(rds_page_remainders, cpu);
197
198 rdsdebug("cpu %ld action 0x%lx\n", cpu, action);
199
200 switch (action) {
201 case CPU_DEAD:
202 if (rem->r_page)
203 __free_page(rem->r_page);
204 rem->r_page = NULL;
205 break;
206 }
207
208 return 0;
209}
210
211static struct notifier_block rds_page_remainder_nb = {
212 .notifier_call = rds_page_remainder_cpu_notify,
213};
214
215void rds_page_exit(void)
216{
217 int i;
218
219 for_each_possible_cpu(i)
220 rds_page_remainder_cpu_notify(&rds_page_remainder_nb,
221 (unsigned long)CPU_DEAD,
222 (void *)(long)i);
223}