From 7875e18e09961d29f30424c5e2e48e704dc3789b Mon Sep 17 00:00:00 2001 From: Andy Grover Date: Tue, 24 Feb 2009 15:30:26 +0000 Subject: RDS: Message parsing Parsing of newly-received RDS message headers (including ext. headers) and copy-to/from-user routines. page.c implements a per-cpu page remainder cache, to reduce the number of allocations needed for small datagrams. Signed-off-by: Andy Grover Signed-off-by: David S. Miller --- net/rds/page.c | 221 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 221 insertions(+) create mode 100644 net/rds/page.c (limited to 'net/rds/page.c') diff --git a/net/rds/page.c b/net/rds/page.c new file mode 100644 index 00000000000..c460743a89a --- /dev/null +++ b/net/rds/page.c @@ -0,0 +1,221 @@ +/* + * 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 + +#include "rds.h" + +struct rds_page_remainder { + struct page *r_page; + unsigned long r_offset; +}; + +DEFINE_PER_CPU(struct rds_page_remainder, rds_page_remainders) ____cacheline_aligned; + +/* + * 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; +} + +/* + * 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); +} -- cgit v1.2.3