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 #include <linux/cpu.h> 36 #include <linux/export.h> 37 38 #include "rds.h" 39 40 struct rds_page_remainder { 41 struct page *r_page; 42 unsigned long r_offset; 43 }; 44 45 static DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, 46 rds_page_remainders); 47 48 /* 49 * returns 0 on success or -errno on failure. 50 * 51 * We don't have to worry about flush_dcache_page() as this only works 52 * with private pages. If, say, we were to do directed receive to pinned 53 * user pages we'd have to worry more about cache coherence. (Though 54 * the flush_dcache_page() in get_user_pages() would probably be enough). 55 */ 56 int rds_page_copy_user(struct page *page, unsigned long offset, 57 void __user *ptr, unsigned long bytes, 58 int to_user) 59 { 60 unsigned long ret; 61 void *addr; 62 63 addr = kmap(page); 64 if (to_user) { 65 rds_stats_add(s_copy_to_user, bytes); 66 ret = copy_to_user(ptr, addr + offset, bytes); 67 } else { 68 rds_stats_add(s_copy_from_user, bytes); 69 ret = copy_from_user(addr + offset, ptr, bytes); 70 } 71 kunmap(page); 72 73 return ret ? -EFAULT : 0; 74 } 75 EXPORT_SYMBOL_GPL(rds_page_copy_user); 76 77 /* 78 * Message allocation uses this to build up regions of a message. 79 * 80 * @bytes - the number of bytes needed. 81 * @gfp - the waiting behaviour of the allocation 82 * 83 * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to 84 * kmap the pages, etc. 85 * 86 * If @bytes is at least a full page then this just returns a page from 87 * alloc_page(). 88 * 89 * If @bytes is a partial page then this stores the unused region of the 90 * page in a per-cpu structure. Future partial-page allocations may be 91 * satisfied from that cached region. This lets us waste less memory on 92 * small allocations with minimal complexity. It works because the transmit 93 * path passes read-only page regions down to devices. They hold a page 94 * reference until they are done with the region. 95 */ 96 int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes, 97 gfp_t gfp) 98 { 99 struct rds_page_remainder *rem; 100 unsigned long flags; 101 struct page *page; 102 int ret; 103 104 gfp |= __GFP_HIGHMEM; 105 106 /* jump straight to allocation if we're trying for a huge page */ 107 if (bytes >= PAGE_SIZE) { 108 page = alloc_page(gfp); 109 if (!page) { 110 ret = -ENOMEM; 111 } else { 112 sg_set_page(scat, page, PAGE_SIZE, 0); 113 ret = 0; 114 } 115 goto out; 116 } 117 118 rem = &per_cpu(rds_page_remainders, get_cpu()); 119 local_irq_save(flags); 120 121 while (1) { 122 /* avoid a tiny region getting stuck by tossing it */ 123 if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) { 124 rds_stats_inc(s_page_remainder_miss); 125 __free_page(rem->r_page); 126 rem->r_page = NULL; 127 } 128 129 /* hand out a fragment from the cached page */ 130 if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) { 131 sg_set_page(scat, rem->r_page, bytes, rem->r_offset); 132 get_page(sg_page(scat)); 133 134 if (rem->r_offset != 0) 135 rds_stats_inc(s_page_remainder_hit); 136 137 rem->r_offset += bytes; 138 if (rem->r_offset == PAGE_SIZE) { 139 __free_page(rem->r_page); 140 rem->r_page = NULL; 141 } 142 ret = 0; 143 break; 144 } 145 146 /* alloc if there is nothing for us to use */ 147 local_irq_restore(flags); 148 put_cpu(); 149 150 page = alloc_page(gfp); 151 152 rem = &per_cpu(rds_page_remainders, get_cpu()); 153 local_irq_save(flags); 154 155 if (!page) { 156 ret = -ENOMEM; 157 break; 158 } 159 160 /* did someone race to fill the remainder before us? */ 161 if (rem->r_page) { 162 __free_page(page); 163 continue; 164 } 165 166 /* otherwise install our page and loop around to alloc */ 167 rem->r_page = page; 168 rem->r_offset = 0; 169 } 170 171 local_irq_restore(flags); 172 put_cpu(); 173 out: 174 rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret, 175 ret ? NULL : sg_page(scat), ret ? 0 : scat->offset, 176 ret ? 0 : scat->length); 177 return ret; 178 } 179 EXPORT_SYMBOL_GPL(rds_page_remainder_alloc); 180 181 static int rds_page_remainder_cpu_notify(struct notifier_block *self, 182 unsigned long action, void *hcpu) 183 { 184 struct rds_page_remainder *rem; 185 long cpu = (long)hcpu; 186 187 rem = &per_cpu(rds_page_remainders, cpu); 188 189 rdsdebug("cpu %ld action 0x%lx\n", cpu, action); 190 191 switch (action) { 192 case CPU_DEAD: 193 if (rem->r_page) 194 __free_page(rem->r_page); 195 rem->r_page = NULL; 196 break; 197 } 198 199 return 0; 200 } 201 202 static struct notifier_block rds_page_remainder_nb = { 203 .notifier_call = rds_page_remainder_cpu_notify, 204 }; 205 206 void rds_page_exit(void) 207 { 208 int i; 209 210 for_each_possible_cpu(i) 211 rds_page_remainder_cpu_notify(&rds_page_remainder_nb, 212 (unsigned long)CPU_DEAD, 213 (void *)(long)i); 214 } 215