blob: 36790122dfd4c3cb869960ddb2141cd235973e16 [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>
34
35#include "rds.h"
36
37struct rds_page_remainder {
38 struct page *r_page;
39 unsigned long r_offset;
40};
41
Tejun Heob9bf3122009-06-24 15:13:47 +090042DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders);
Andy Grover7875e182009-02-24 15:30:26 +000043
44/*
45 * returns 0 on success or -errno on failure.
46 *
47 * We don't have to worry about flush_dcache_page() as this only works
48 * with private pages. If, say, we were to do directed receive to pinned
49 * user pages we'd have to worry more about cache coherence. (Though
50 * the flush_dcache_page() in get_user_pages() would probably be enough).
51 */
52int rds_page_copy_user(struct page *page, unsigned long offset,
53 void __user *ptr, unsigned long bytes,
54 int to_user)
55{
56 unsigned long ret;
57 void *addr;
58
59 if (to_user)
60 rds_stats_add(s_copy_to_user, bytes);
61 else
62 rds_stats_add(s_copy_from_user, bytes);
63
64 addr = kmap_atomic(page, KM_USER0);
65 if (to_user)
66 ret = __copy_to_user_inatomic(ptr, addr + offset, bytes);
67 else
68 ret = __copy_from_user_inatomic(addr + offset, ptr, bytes);
69 kunmap_atomic(addr, KM_USER0);
70
71 if (ret) {
72 addr = kmap(page);
73 if (to_user)
74 ret = copy_to_user(ptr, addr + offset, bytes);
75 else
76 ret = copy_from_user(addr + offset, ptr, bytes);
77 kunmap(page);
78 if (ret)
79 return -EFAULT;
80 }
81
82 return 0;
83}
Andy Grover616b7572009-08-21 12:28:32 +000084EXPORT_SYMBOL_GPL(rds_page_copy_user);
Andy Grover7875e182009-02-24 15:30:26 +000085
86/*
87 * Message allocation uses this to build up regions of a message.
88 *
89 * @bytes - the number of bytes needed.
90 * @gfp - the waiting behaviour of the allocation
91 *
92 * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to
93 * kmap the pages, etc.
94 *
95 * If @bytes is at least a full page then this just returns a page from
96 * alloc_page().
97 *
98 * If @bytes is a partial page then this stores the unused region of the
99 * page in a per-cpu structure. Future partial-page allocations may be
100 * satisfied from that cached region. This lets us waste less memory on
101 * small allocations with minimal complexity. It works because the transmit
102 * path passes read-only page regions down to devices. They hold a page
103 * reference until they are done with the region.
104 */
105int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
106 gfp_t gfp)
107{
108 struct rds_page_remainder *rem;
109 unsigned long flags;
110 struct page *page;
111 int ret;
112
113 gfp |= __GFP_HIGHMEM;
114
115 /* jump straight to allocation if we're trying for a huge page */
116 if (bytes >= PAGE_SIZE) {
117 page = alloc_page(gfp);
118 if (page == NULL) {
119 ret = -ENOMEM;
120 } else {
121 sg_set_page(scat, page, PAGE_SIZE, 0);
122 ret = 0;
123 }
124 goto out;
125 }
126
127 rem = &per_cpu(rds_page_remainders, get_cpu());
128 local_irq_save(flags);
129
130 while (1) {
131 /* avoid a tiny region getting stuck by tossing it */
132 if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) {
133 rds_stats_inc(s_page_remainder_miss);
134 __free_page(rem->r_page);
135 rem->r_page = NULL;
136 }
137
138 /* hand out a fragment from the cached page */
139 if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) {
140 sg_set_page(scat, rem->r_page, bytes, rem->r_offset);
141 get_page(sg_page(scat));
142
143 if (rem->r_offset != 0)
144 rds_stats_inc(s_page_remainder_hit);
145
146 rem->r_offset += bytes;
147 if (rem->r_offset == PAGE_SIZE) {
148 __free_page(rem->r_page);
149 rem->r_page = NULL;
150 }
151 ret = 0;
152 break;
153 }
154
155 /* alloc if there is nothing for us to use */
156 local_irq_restore(flags);
157 put_cpu();
158
159 page = alloc_page(gfp);
160
161 rem = &per_cpu(rds_page_remainders, get_cpu());
162 local_irq_save(flags);
163
164 if (page == NULL) {
165 ret = -ENOMEM;
166 break;
167 }
168
169 /* did someone race to fill the remainder before us? */
170 if (rem->r_page) {
171 __free_page(page);
172 continue;
173 }
174
175 /* otherwise install our page and loop around to alloc */
176 rem->r_page = page;
177 rem->r_offset = 0;
178 }
179
180 local_irq_restore(flags);
181 put_cpu();
182out:
183 rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
184 ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
185 ret ? 0 : scat->length);
186 return ret;
187}
188
189static int rds_page_remainder_cpu_notify(struct notifier_block *self,
190 unsigned long action, void *hcpu)
191{
192 struct rds_page_remainder *rem;
193 long cpu = (long)hcpu;
194
195 rem = &per_cpu(rds_page_remainders, cpu);
196
197 rdsdebug("cpu %ld action 0x%lx\n", cpu, action);
198
199 switch (action) {
200 case CPU_DEAD:
201 if (rem->r_page)
202 __free_page(rem->r_page);
203 rem->r_page = NULL;
204 break;
205 }
206
207 return 0;
208}
209
210static struct notifier_block rds_page_remainder_nb = {
211 .notifier_call = rds_page_remainder_cpu_notify,
212};
213
214void rds_page_exit(void)
215{
216 int i;
217
218 for_each_possible_cpu(i)
219 rds_page_remainder_cpu_notify(&rds_page_remainder_nb,
220 (unsigned long)CPU_DEAD,
221 (void *)(long)i);
222}