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/highmem.h> 34 35 #include "rds.h" 36 37 struct rds_page_remainder { 38 struct page *r_page; 39 unsigned long r_offset; 40 }; 41 42 DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders); 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 */ 52 int 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 EXPORT_SYMBOL_GPL(rds_page_copy_user); 85 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 */ 105 int 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(); 182 out: 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 } 188 189 static 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 } 209 210 static struct notifier_block rds_page_remainder_nb = { 211 .notifier_call = rds_page_remainder_cpu_notify, 212 }; 213 214 void 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 } 223