/* * Copyright (c) 2006 Oracle. All rights reserved. * * This software is available to you under a choice of one of two * licenses. You may choose to be licensed under the terms of the GNU * General Public License (GPL) Version 2, available from the file * COPYING in the main directory of this source tree, or the * OpenIB.org BSD license below: * * Redistribution and use in source and binary forms, with or * without modification, are permitted provided that the following * conditions are met: * * - Redistributions of source code must retain the above * copyright notice, this list of conditions and the following * disclaimer. * * - Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following * disclaimer in the documentation and/or other materials * provided with the distribution. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE * SOFTWARE. * */ #include <linux/highmem.h> #include <linux/gfp.h> #include "rds.h" struct rds_page_remainder { struct page *r_page; unsigned long r_offset; }; DEFINE_PER_CPU_SHARED_ALIGNED(struct rds_page_remainder, rds_page_remainders); /* * returns 0 on success or -errno on failure. * * We don't have to worry about flush_dcache_page() as this only works * with private pages. If, say, we were to do directed receive to pinned * user pages we'd have to worry more about cache coherence. (Though * the flush_dcache_page() in get_user_pages() would probably be enough). */ int rds_page_copy_user(struct page *page, unsigned long offset, void __user *ptr, unsigned long bytes, int to_user) { unsigned long ret; void *addr; if (to_user) rds_stats_add(s_copy_to_user, bytes); else rds_stats_add(s_copy_from_user, bytes); addr = kmap_atomic(page, KM_USER0); if (to_user) ret = __copy_to_user_inatomic(ptr, addr + offset, bytes); else ret = __copy_from_user_inatomic(addr + offset, ptr, bytes); kunmap_atomic(addr, KM_USER0); if (ret) { addr = kmap(page); if (to_user) ret = copy_to_user(ptr, addr + offset, bytes); else ret = copy_from_user(addr + offset, ptr, bytes); kunmap(page); if (ret) return -EFAULT; } return 0; } EXPORT_SYMBOL_GPL(rds_page_copy_user); /* * Message allocation uses this to build up regions of a message. * * @bytes - the number of bytes needed. * @gfp - the waiting behaviour of the allocation * * @gfp is always ored with __GFP_HIGHMEM. Callers must be prepared to * kmap the pages, etc. * * If @bytes is at least a full page then this just returns a page from * alloc_page(). * * If @bytes is a partial page then this stores the unused region of the * page in a per-cpu structure. Future partial-page allocations may be * satisfied from that cached region. This lets us waste less memory on * small allocations with minimal complexity. It works because the transmit * path passes read-only page regions down to devices. They hold a page * reference until they are done with the region. */ int rds_page_remainder_alloc(struct scatterlist *scat, unsigned long bytes, gfp_t gfp) { struct rds_page_remainder *rem; unsigned long flags; struct page *page; int ret; gfp |= __GFP_HIGHMEM; /* jump straight to allocation if we're trying for a huge page */ if (bytes >= PAGE_SIZE) { page = alloc_page(gfp); if (page == NULL) { ret = -ENOMEM; } else { sg_set_page(scat, page, PAGE_SIZE, 0); ret = 0; } goto out; } rem = &per_cpu(rds_page_remainders, get_cpu()); local_irq_save(flags); while (1) { /* avoid a tiny region getting stuck by tossing it */ if (rem->r_page && bytes > (PAGE_SIZE - rem->r_offset)) { rds_stats_inc(s_page_remainder_miss); __free_page(rem->r_page); rem->r_page = NULL; } /* hand out a fragment from the cached page */ if (rem->r_page && bytes <= (PAGE_SIZE - rem->r_offset)) { sg_set_page(scat, rem->r_page, bytes, rem->r_offset); get_page(sg_page(scat)); if (rem->r_offset != 0) rds_stats_inc(s_page_remainder_hit); rem->r_offset += bytes; if (rem->r_offset == PAGE_SIZE) { __free_page(rem->r_page); rem->r_page = NULL; } ret = 0; break; } /* alloc if there is nothing for us to use */ local_irq_restore(flags); put_cpu(); page = alloc_page(gfp); rem = &per_cpu(rds_page_remainders, get_cpu()); local_irq_save(flags); if (page == NULL) { ret = -ENOMEM; break; } /* did someone race to fill the remainder before us? */ if (rem->r_page) { __free_page(page); continue; } /* otherwise install our page and loop around to alloc */ rem->r_page = page; rem->r_offset = 0; } local_irq_restore(flags); put_cpu(); out: rdsdebug("bytes %lu ret %d %p %u %u\n", bytes, ret, ret ? NULL : sg_page(scat), ret ? 0 : scat->offset, ret ? 0 : scat->length); return ret; } static int rds_page_remainder_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { struct rds_page_remainder *rem; long cpu = (long)hcpu; rem = &per_cpu(rds_page_remainders, cpu); rdsdebug("cpu %ld action 0x%lx\n", cpu, action); switch (action) { case CPU_DEAD: if (rem->r_page) __free_page(rem->r_page); rem->r_page = NULL; break; } return 0; } static struct notifier_block rds_page_remainder_nb = { .notifier_call = rds_page_remainder_cpu_notify, }; void rds_page_exit(void) { int i; for_each_possible_cpu(i) rds_page_remainder_cpu_notify(&rds_page_remainder_nb, (unsigned long)CPU_DEAD, (void *)(long)i); }