blob: c460743a89ad00c594fd8f606c083321e0ee8b39 [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
42DEFINE_PER_CPU(struct rds_page_remainder, rds_page_remainders) ____cacheline_aligned;
43
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}
84
85/*
86 * Message allocation uses this to build up regions of a message.
87 *
88 * @bytes - the number of bytes needed.
89 * @gfp - the waiting behaviour of the allocation
90 *
91 * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to
92 * kmap the pages, etc.
93 *
94 * If @bytes is at least a full page then this just returns a page from
95 * alloc_page().
96 *
97 * If @bytes is a partial page then this stores the unused region of the
98 * page in a per-cpu structure. Future partial-page allocations may be
99 * satisfied from that cached region. This lets us waste less memory on
100 * small allocations with minimal complexity. It works because the transmit
101 * path passes read-only page regions down to devices. They hold a page
102 * reference until they are done with the region.
103 */
104int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes,
105 gfp_t gfp)
106{
107 struct rds_page_remainder *rem;
108 unsigned long flags;
109 struct page *page;
110 int ret;
111
112 gfp |= __GFP_HIGHMEM;
113
114 /* jump straight to allocation if we're trying for a huge page */
115 if (bytes >= PAGE_SIZE) {
116 page = alloc_page(gfp);
117 if (page == NULL) {
118 ret = -ENOMEM;
119 } else {
120 sg_set_page(scat, page, PAGE_SIZE, 0);
121 ret = 0;
122 }
123 goto out;
124 }
125
126 rem = &per_cpu(rds_page_remainders, get_cpu());
127 local_irq_save(flags);
128
129 while (1) {
130 /* avoid a tiny region getting stuck by tossing it */
131 if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) {
132 rds_stats_inc(s_page_remainder_miss);
133 __free_page(rem->r_page);
134 rem->r_page = NULL;
135 }
136
137 /* hand out a fragment from the cached page */
138 if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) {
139 sg_set_page(scat, rem->r_page, bytes, rem->r_offset);
140 get_page(sg_page(scat));
141
142 if (rem->r_offset != 0)
143 rds_stats_inc(s_page_remainder_hit);
144
145 rem->r_offset += bytes;
146 if (rem->r_offset == PAGE_SIZE) {
147 __free_page(rem->r_page);
148 rem->r_page = NULL;
149 }
150 ret = 0;
151 break;
152 }
153
154 /* alloc if there is nothing for us to use */
155 local_irq_restore(flags);
156 put_cpu();
157
158 page = alloc_page(gfp);
159
160 rem = &per_cpu(rds_page_remainders, get_cpu());
161 local_irq_save(flags);
162
163 if (page == NULL) {
164 ret = -ENOMEM;
165 break;
166 }
167
168 /* did someone race to fill the remainder before us? */
169 if (rem->r_page) {
170 __free_page(page);
171 continue;
172 }
173
174 /* otherwise install our page and loop around to alloc */
175 rem->r_page = page;
176 rem->r_offset = 0;
177 }
178
179 local_irq_restore(flags);
180 put_cpu();
181out:
182 rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret,
183 ret ? NULL : sg_page(scat), ret ? 0 : scat->offset,
184 ret ? 0 : scat->length);
185 return ret;
186}
187
188static int rds_page_remainder_cpu_notify(struct notifier_block *self,
189 unsigned long action, void *hcpu)
190{
191 struct rds_page_remainder *rem;
192 long cpu = (long)hcpu;
193
194 rem = &per_cpu(rds_page_remainders, cpu);
195
196 rdsdebug("cpu %ld action 0x%lx\n", cpu, action);
197
198 switch (action) {
199 case CPU_DEAD:
200 if (rem->r_page)
201 __free_page(rem->r_page);
202 rem->r_page = NULL;
203 break;
204 }
205
206 return 0;
207}
208
209static struct notifier_block rds_page_remainder_nb = {
210 .notifier_call = rds_page_remainder_cpu_notify,
211};
212
213void rds_page_exit(void)
214{
215 int i;
216
217 for_each_possible_cpu(i)
218 rds_page_remainder_cpu_notify(&rds_page_remainder_nb,
219 (unsigned long)CPU_DEAD,
220 (void *)(long)i);
221}