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242 lines
6.4 KiB
242 lines
6.4 KiB
/* |
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* Copyright (c) 2006 Oracle. All rights reserved. |
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* |
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* This software is available to you under a choice of one of two |
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* licenses. You may choose to be licensed under the terms of the GNU |
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* General Public License (GPL) Version 2, available from the file |
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* COPYING in the main directory of this source tree, or the |
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* OpenIB.org BSD license below: |
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* |
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* Redistribution and use in source and binary forms, with or |
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* without modification, are permitted provided that the following |
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* conditions are met: |
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* |
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* - Redistributions of source code must retain the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer. |
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* |
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* - Redistributions in binary form must reproduce the above |
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* copyright notice, this list of conditions and the following |
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* disclaimer in the documentation and/or other materials |
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* provided with the distribution. |
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* |
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS |
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN |
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
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* SOFTWARE. |
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* |
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*/ |
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#include <linux/percpu.h> |
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#include <linux/seq_file.h> |
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#include <linux/slab.h> |
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#include <linux/proc_fs.h> |
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#include <linux/export.h> |
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#include "rds.h" |
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/* |
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* This file implements a getsockopt() call which copies a set of fixed |
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* sized structs into a user-specified buffer as a means of providing |
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* read-only information about RDS. |
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* |
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* For a given information source there are a given number of fixed sized |
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* structs at a given time. The structs are only copied if the user-specified |
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* buffer is big enough. The destination pages that make up the buffer |
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* are pinned for the duration of the copy. |
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* |
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* This gives us the following benefits: |
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* |
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* - simple implementation, no copy "position" across multiple calls |
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* - consistent snapshot of an info source |
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* - atomic copy works well with whatever locking info source has |
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* - one portable tool to get rds info across implementations |
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* - long-lived tool can get info without allocating |
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* |
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* at the following costs: |
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* |
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* - info source copy must be pinned, may be "large" |
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*/ |
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struct rds_info_iterator { |
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struct page **pages; |
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void *addr; |
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unsigned long offset; |
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}; |
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static DEFINE_SPINLOCK(rds_info_lock); |
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static rds_info_func rds_info_funcs[RDS_INFO_LAST - RDS_INFO_FIRST + 1]; |
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void rds_info_register_func(int optname, rds_info_func func) |
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{ |
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int offset = optname - RDS_INFO_FIRST; |
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BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST); |
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spin_lock(&rds_info_lock); |
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BUG_ON(rds_info_funcs[offset]); |
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rds_info_funcs[offset] = func; |
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spin_unlock(&rds_info_lock); |
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} |
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EXPORT_SYMBOL_GPL(rds_info_register_func); |
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void rds_info_deregister_func(int optname, rds_info_func func) |
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{ |
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int offset = optname - RDS_INFO_FIRST; |
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BUG_ON(optname < RDS_INFO_FIRST || optname > RDS_INFO_LAST); |
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spin_lock(&rds_info_lock); |
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BUG_ON(rds_info_funcs[offset] != func); |
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rds_info_funcs[offset] = NULL; |
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spin_unlock(&rds_info_lock); |
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} |
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EXPORT_SYMBOL_GPL(rds_info_deregister_func); |
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/* |
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* Typically we hold an atomic kmap across multiple rds_info_copy() calls |
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* because the kmap is so expensive. This must be called before using blocking |
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* operations while holding the mapping and as the iterator is torn down. |
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*/ |
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void rds_info_iter_unmap(struct rds_info_iterator *iter) |
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{ |
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if (iter->addr) { |
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kunmap_atomic(iter->addr); |
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iter->addr = NULL; |
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} |
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} |
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/* |
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* get_user_pages() called flush_dcache_page() on the pages for us. |
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*/ |
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void rds_info_copy(struct rds_info_iterator *iter, void *data, |
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unsigned long bytes) |
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{ |
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unsigned long this; |
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while (bytes) { |
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if (!iter->addr) |
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iter->addr = kmap_atomic(*iter->pages); |
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this = min(bytes, PAGE_SIZE - iter->offset); |
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rdsdebug("page %p addr %p offset %lu this %lu data %p " |
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"bytes %lu\n", *iter->pages, iter->addr, |
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iter->offset, this, data, bytes); |
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memcpy(iter->addr + iter->offset, data, this); |
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data += this; |
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bytes -= this; |
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iter->offset += this; |
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if (iter->offset == PAGE_SIZE) { |
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kunmap_atomic(iter->addr); |
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iter->addr = NULL; |
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iter->offset = 0; |
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iter->pages++; |
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} |
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} |
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} |
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EXPORT_SYMBOL_GPL(rds_info_copy); |
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/* |
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* @optval points to the userspace buffer that the information snapshot |
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* will be copied into. |
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* |
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* @optlen on input is the size of the buffer in userspace. @optlen |
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* on output is the size of the requested snapshot in bytes. |
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* |
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* This function returns -errno if there is a failure, particularly -ENOSPC |
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* if the given userspace buffer was not large enough to fit the snapshot. |
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* On success it returns the positive number of bytes of each array element |
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* in the snapshot. |
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*/ |
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int rds_info_getsockopt(struct socket *sock, int optname, char __user *optval, |
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int __user *optlen) |
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{ |
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struct rds_info_iterator iter; |
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struct rds_info_lengths lens; |
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unsigned long nr_pages = 0; |
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unsigned long start; |
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rds_info_func func; |
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struct page **pages = NULL; |
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int ret; |
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int len; |
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int total; |
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if (get_user(len, optlen)) { |
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ret = -EFAULT; |
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goto out; |
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} |
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/* check for all kinds of wrapping and the like */ |
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start = (unsigned long)optval; |
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if (len < 0 || len > INT_MAX - PAGE_SIZE + 1 || start + len < start) { |
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ret = -EINVAL; |
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goto out; |
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} |
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/* a 0 len call is just trying to probe its length */ |
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if (len == 0) |
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goto call_func; |
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nr_pages = (PAGE_ALIGN(start + len) - (start & PAGE_MASK)) |
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>> PAGE_SHIFT; |
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pages = kmalloc_array(nr_pages, sizeof(struct page *), GFP_KERNEL); |
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if (!pages) { |
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ret = -ENOMEM; |
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goto out; |
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} |
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ret = pin_user_pages_fast(start, nr_pages, FOLL_WRITE, pages); |
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if (ret != nr_pages) { |
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if (ret > 0) |
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nr_pages = ret; |
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else |
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nr_pages = 0; |
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ret = -EAGAIN; /* XXX ? */ |
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goto out; |
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} |
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rdsdebug("len %d nr_pages %lu\n", len, nr_pages); |
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call_func: |
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func = rds_info_funcs[optname - RDS_INFO_FIRST]; |
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if (!func) { |
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ret = -ENOPROTOOPT; |
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goto out; |
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} |
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iter.pages = pages; |
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iter.addr = NULL; |
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iter.offset = start & (PAGE_SIZE - 1); |
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func(sock, len, &iter, &lens); |
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BUG_ON(lens.each == 0); |
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total = lens.nr * lens.each; |
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rds_info_iter_unmap(&iter); |
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if (total > len) { |
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len = total; |
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ret = -ENOSPC; |
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} else { |
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len = total; |
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ret = lens.each; |
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} |
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if (put_user(len, optlen)) |
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ret = -EFAULT; |
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out: |
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if (pages) |
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unpin_user_pages(pages, nr_pages); |
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kfree(pages); |
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return ret; |
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}
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