/*
* Public API and common code for kernel->userspace relay file support.
*
* See Documentation/filesystems/relay.txt for an overview.
*
* Copyright (C) 2002-2005 - Tom Zanussi (zanussi@us.ibm.com), IBM Corp
* Copyright (C) 1999-2005 - Karim Yaghmour (karim@opersys.com)
*
* Moved to kernel/relay.c by Paul Mundt, 2006.
* November 2006 - CPU hotplug support by Mathieu Desnoyers
* (mathieu.desnoyers@polymtl.ca)
*
* This file is released under the GPL.
*/
#include <linux/errno.h>
#include <linux/stddef.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/relay.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/cpu.h>
#include <linux/splice.h>
/* list of open channels, for cpu hotplug */
static DEFINE_MUTEX(relay_channels_mutex);
static LIST_HEAD(relay_channels);
/*
* close() vm_op implementation for relay file mapping.
*/
static void relay_file_mmap_close(struct vm_area_struct *vma)
{
struct rchan_buf *buf = vma->vm_private_data;
buf->chan->cb->buf_unmapped(buf, vma->vm_file);
}
/*
* fault() vm_op implementation for relay file mapping.
*/
static int relay_buf_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
{
struct page *page;
struct rchan_buf *buf = vma->vm_private_data;
pgoff_t pgoff = vmf->pgoff;
if (!buf)
return VM_FAULT_OOM;
page = vmalloc_to_page(buf->start + (pgoff << PAGE_SHIFT));
if (!page)
return VM_FAULT_SIGBUS;
get_page(page);
vmf->page = page;
return 0;
}
/*
* vm_ops for relay file mappings.
*/
static const struct vm_operations_struct relay_file_mmap_ops = {
.fault = relay_buf_fault,
.close = relay_file_mmap_close,
};
/*
* allocate an array of pointers of struct page
*/
static struct page **relay_alloc_page_array(unsigned int n_pages)
{
struct page **array;
size_t pa_size = n_pages * sizeof(struct page *);
if (pa_size > PAGE_SIZE) {
array = vmalloc(pa_size);
if (array)
memset(array, 0, pa_size);
} 