/*
* 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;
}
