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 #include <linux/gfp.h> 35 36 #include "rds.h" 37 38 struct rds_page_remainder { 39 struct page *r_page; 40 unsigned long r_offset; 41 }; 42 43 DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders); 44 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 */ 53 int 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 } 85 EXPORT_SYMBOL_GPL(rds_page_copy_user); 86 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 */ 106 int 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(); 183 out: 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 } 189 190 static 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 } 210 211 static struct notifier_block rds_page_remainder_nb = { 212 .notifier_call = rds_page_remainder_cpu_notify, 213 }; 214 215 void 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 } 224