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Diffstat (limited to 'net/rds/info.c')
| -rw-r--r-- | net/rds/info.c | 241 |
1 files changed, 241 insertions, 0 deletions
diff --git a/net/rds/info.c b/net/rds/info.c new file mode 100644 index 000000000000..1d885535214d --- /dev/null +++ b/net/rds/info.c @@ -0,0 +1,241 @@ +/* + * 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/proc_fs.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] != NULL); + rds_info_funcs[offset] = func; + spin_unlock(&rds_info_lock); +} + +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); +} + +/* + * 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 != NULL) { + kunmap_atomic(iter->addr, KM_USER0); + 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 == NULL) + iter->addr = kmap_atomic(*iter->pages, KM_USER0); + + 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, KM_USER0); + iter->addr = NULL; + iter->offset = 0; + iter->pages++; + } + } +} + +/* + * @optval points to the userspace buffer that the information snapshot + * will be copied into. + * + * @optlen on input is the size of the buffer in userspace. @optlen + * on output is the size of the requested snapshot in bytes. + * + * This function returns -errno if there is a failure, particularly -ENOSPC + * if the given userspace 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, char __user *optval, + int __user *optlen) +{ + struct rds_info_iterator iter; + struct rds_info_lengths lens; + unsigned long nr_pages = 0; + unsigned long start; + unsigned long i; + rds_info_func func; + struct page **pages = NULL; + int ret; + int len; + int total; + + if (get_user(len, optlen)) { + ret = -EFAULT; + goto out; + } + + /* check for all kinds of wrapping and the like */ + start = (unsigned long)optval; + if (len < 0 || len + PAGE_SIZE - 1 < len || start + len < start) { + ret = -EINVAL; + goto out; + } + + /* a 0 len call is just trying to probe its length */ + if (len == 0) + goto call_func; + + nr_pages = (PAGE_ALIGN(start + len) - (start & PAGE_MASK)) + >> PAGE_SHIFT; + + pages = kmalloc(nr_pages * sizeof(struct page *), GFP_KERNEL); + if (pages == NULL) { + ret = -ENOMEM; + goto out; + } + down_read(¤t->mm->mmap_sem); + ret = get_user_pages(current, current->mm, start, nr_pages, 1, 0, + pages, NULL); + up_read(¤t->mm->mmap_sem); + if (ret != nr_pages) { + if (ret > 0) + nr_pages = ret; + else + nr_pages = 0; + 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 == NULL) { + ret = -ENOPROTOOPT; + goto out; + } + + iter.pages = pages; + iter.addr = NULL; + iter.offset = start & (PAGE_SIZE - 1); + + 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; + } + + if (put_user(len, optlen)) + ret = -EFAULT; + +out: + for (i = 0; pages != NULL && i < nr_pages; i++) + put_page(pages[i]); + kfree(pages); + + return ret; +} |