1/*
2 * Copyright (c) 2013-2015, Mellanox Technologies. All rights reserved.
3 *
4 * This software is available to you under a choice of one of two
5 * licenses.  You may choose to be licensed under the terms of the GNU
6 * General Public License (GPL) Version 2, available from the file
7 * COPYING in the main directory of this source tree, or the
8 * OpenIB.org BSD license below:
9 *
10 *     Redistribution and use in source and binary forms, with or
11 *     without modification, are permitted provided that the following
12 *     conditions are met:
13 *
14 *      - Redistributions of source code must retain the above
15 *        copyright notice, this list of conditions and the following
16 *        disclaimer.
17 *
18 *      - Redistributions in binary form must reproduce the above
19 *        copyright notice, this list of conditions and the following
20 *        disclaimer in the documentation and/or other materials
21 *        provided with the distribution.
22 *
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 * SOFTWARE.
31 */
32
33#include <linux/kref.h>
34#include <linux/slab.h>
35#include <linux/sched/mm.h>
36#include <rdma/ib_umem.h>
37
38#include "mlx5_ib.h"
39
40struct mlx5_ib_user_db_page {
41	struct list_head	list;
42	struct ib_umem	       *umem;
43	unsigned long		user_virt;
44	int			refcnt;
45	struct mm_struct	*mm;
46};
47
48int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context, unsigned long virt,
49			struct mlx5_db *db)
50{
51	struct mlx5_ib_user_db_page *page;
52	int err = 0;
53
54	mutex_lock(&context->db_page_mutex);
55
56	list_for_each_entry(page, &context->db_page_list, list)
57		if ((current->mm == page->mm) &&
58		    (page->user_virt == (virt & PAGE_MASK)))
59			goto found;
60
61	page = kmalloc(sizeof(*page), GFP_KERNEL);
62	if (!page) {
63		err = -ENOMEM;
64		goto out;
65	}
66
67	page->user_virt = (virt & PAGE_MASK);
68	page->refcnt    = 0;
69	page->umem = ib_umem_get(context->ibucontext.device, virt & PAGE_MASK,
70				 PAGE_SIZE, 0);
71	if (IS_ERR(page->umem)) {
72		err = PTR_ERR(page->umem);
73		kfree(page);
74		goto out;
75	}
76	mmgrab(current->mm);
77	page->mm = current->mm;
78
79	list_add(&page->list, &context->db_page_list);
80
81found:
82	db->dma = sg_dma_address(page->umem->sgt_append.sgt.sgl) +
83		  (virt & ~PAGE_MASK);
84	db->u.user_page = page;
85	++page->refcnt;
86
87out:
88	mutex_unlock(&context->db_page_mutex);
89
90	return err;
91}
92
93void mlx5_ib_db_unmap_user(struct mlx5_ib_ucontext *context, struct mlx5_db *db)
94{
95	mutex_lock(&context->db_page_mutex);
96
97	if (!--db->u.user_page->refcnt) {
98		list_del(&db->u.user_page->list);
99		mmdrop(db->u.user_page->mm);
100		ib_umem_release(db->u.user_page->umem);
101		kfree(db->u.user_page);
102	}
103
104	mutex_unlock(&context->db_page_mutex);
105}
106