/* * 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/srcu.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;}; DEFINE_STATIC_SRCU(rds_info_srcu);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);	if (WARN_ON_ONCE(rds_info_funcs[offset])) {		spin_unlock(&rds_info_lock);		return;	}	WRITE_ONCE(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);	if (WARN_ON_ONCE(rds_info_funcs[offset] != func)) {		spin_unlock(&rds_info_lock);		return;	}	WRITE_ONCE(rds_info_funcs[offset], NULL);	spin_unlock(&rds_info_lock);	synchronize_srcu(&rds_info_srcu);}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 srcu_idx;	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_objs(*pages, npages);	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:	srcu_idx = srcu_read_lock(&rds_info_srcu);	func = READ_ONCE(rds_info_funcs[optname - RDS_INFO_FIRST]);	if (!func) {		srcu_read_unlock(&rds_info_srcu, srcu_idx);		ret = -ENOPROTOOPT;		goto out;	} 	iter.pages = pages;	iter.addr = NULL;	iter.offset = offset0; 	func(sock, len, &iter, &lens);	srcu_read_unlock(&rds_info_srcu, srcu_idx);	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;}