/* * 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/percpu.h> #include <linux/seq_file.h> #include <linux/slab.h> #include <linux/proc_fs.h> #include <linux/export.h> #include <linux/uio.h> #include "rds.h" /* * This file implements a getsockopt() call which copies a set of fixed * sized structs into a user-specified buffer as a means of providing * read-only information about RDS. * * For a given information source there are a given number of fixed sized * structs at a given time. The structs are only copied if the user-specified * buffer is big enough. The destination pages that make up the buffer * are pinned for the duration of the copy. * * This gives us the following benefits: * * - simple implementation, no copy "position" across multiple calls * - consistent snapshot of an info source * - atomic copy works well with whatever locking info source has * - one portable tool to get rds info across implementations * - long-lived tool can get info without allocating * * at the following costs: * * - info source copy must be pinned, may be "large" */ struct rds_info_iterator { struct page **pages; void *addr; unsigned long offset; }; static DEFINE_SPINLOCK(rds_info_lock); static rds_info_func rds_info_funcs[RDS_INFO_LAST - RDS_INFO_FIRST + 1]; void rds_info_register_func(int optname, rds_info_func func) { int offset = optname - RDS_INFO_FIRST; BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST); spin_lock(&rds_info_lock); BUG_ON(rds_info_funcs[offset]); rds_info_funcs[offset] = func; spin_unlock(&rds_info_lock); } EXPORT_SYMBOL_GPL(rds_info_register_func); void rds_info_deregister_func(int optname, rds_info_func func) { int offset = optname - RDS_INFO_FIRST; BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST); spin_lock(&rds_info_lock); BUG_ON(rds_info_funcs[offset] != func); rds_info_funcs[offset] = NULL; spin_unlock(&rds_info_lock); } EXPORT_SYMBOL_GPL(rds_info_deregister_func); /* * Typically we hold an atomic kmap across multiple rds_info_copy() calls * because the kmap is so expensive. This must be called before using blocking * operations while holding the mapping and as the iterator is torn down. */ void rds_info_iter_unmap(struct rds_info_iterator *iter) { if (iter->addr) { kunmap_atomic(iter->addr); iter->addr = NULL; } } /* * get_user_pages() called flush_dcache_page() on the pages for us. */ void rds_info_copy(struct rds_info_iterator *iter, void *data, unsigned long bytes) { unsigned long this; while (bytes) { if (!iter->addr) iter->addr = kmap_atomic(*iter->pages); this = min(bytes, PAGE_SIZE - iter->offset); rdsdebug("page %p addr %p offset %lu this %lu data %p " "bytes %lu\n", *iter->pages, iter->addr, iter->offset, this, data, bytes); memcpy(iter->addr + iter->offset, data, this); data += this; bytes -= this; iter->offset += this; if (iter->offset == PAGE_SIZE) { kunmap_atomic(iter->addr); iter->addr = NULL; iter->offset = 0; iter->pages++; } } } EXPORT_SYMBOL_GPL(rds_info_copy); /* * @opt->iter_out describes the buffer that the information snapshot will be * copied into, and @opt->optlen is the size of that buffer on input. On * output @opt->optlen is set to the size of the requested snapshot in bytes. * * This function returns -errno if there is a failure, particularly -ENOSPC * if the given buffer was not large enough to fit the snapshot. On success * it returns the positive number of bytes of each array element in the * snapshot. */ int rds_info_getsockopt(struct socket *sock, int optname, sockopt_t *opt) { struct rds_info_iterator iter; struct rds_info_lengths lens; unsigned long nr_pages = 0; rds_info_func func; struct page **pages = NULL; size_t offset0 = 0; int npages = 0; int ret; int len; int total; len = opt->optlen; /* check for all kinds of wrapping and the like */ if (len < 0 || len > INT_MAX - PAGE_SIZE + 1) { ret = -EINVAL; goto out; } /* The info producers write into the pages with kmap_atomic() while * holding a spinlock, so they need a genuine page-backed user buffer. */ if (!user_backed_iter(&opt->iter_out)) { ret = -EOPNOTSUPP; goto out; } /* a 0 len call is just trying to probe its length */ if (len == 0) goto call_func; /* * Preallocate the page array and pass it in so that * iov_iter_extract_pages() fills it in place rather than allocating * one for us. Handing it a non-NULL array keeps ownership of the * array with us on every return path, instead of depending on the * iterator code to allocate and hand it back. */ npages = iov_iter_npages(&opt->iter_out, INT_MAX); pages = kvmalloc_array(npages, sizeof(*pages), GFP_KERNEL); if (!pages) { ret = -ENOMEM; goto out; } ret = iov_iter_extract_pages(&opt->iter_out, &pages, len, npages, 0, &offset0); if (ret < 0) goto out; nr_pages = DIV_ROUND_UP(offset0 + ret, PAGE_SIZE); if (ret != len) { ret = -EAGAIN; /* XXX ? */ goto out; } rdsdebug("len %d nr_pages %lu\n", len, nr_pages); call_func: func = rds_info_funcs[optname - RDS_INFO_FIRST]; if (!func) { ret = -ENOPROTOOPT; goto out; } iter.pages = pages; iter.addr = NULL; iter.offset = offset0; func(sock, len, &iter, &lens); BUG_ON(lens.each == 0); total = lens.nr * lens.each; rds_info_iter_unmap(&iter); if (total > len) { len = total; ret = -ENOSPC; } else { len = total; ret = lens.each; } opt->optlen = len; out: /* * iov_iter_extract_pages() pins only user-backed (ubuf) iters; * iov_iter_extract_will_pin() reports whether an unpin is owed here. */ if (pages && iov_iter_extract_will_pin(&opt->iter_out)) unpin_user_pages_dirty_lock(pages, nr_pages, true); kvfree(pages); return ret; }
