1 /*-
2  * Copyright (c) 2013-2015, Mellanox Technologies, Ltd.  All rights reserved.
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  * 1. Redistributions of source code must retain the above copyright
8  *    notice, this list of conditions and the following disclaimer.
9  * 2. Redistributions in binary form must reproduce the above copyright
10  *    notice, this list of conditions and the following disclaimer in the
11  *    documentation and/or other materials provided with the distribution.
12  *
13  * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS `AS IS' AND
14  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
16  * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
17  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
18  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
19  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
20  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
21  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
22  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
23  * SUCH DAMAGE.
24  *
25  * $FreeBSD$
26  */
27 
28 #include <linux/kref.h>
29 #include <linux/slab.h>
30 #include <rdma/ib_umem.h>
31 
32 #include "mlx5_ib.h"
33 
34 struct mlx5_ib_user_db_page {
35 	struct list_head	list;
36 	struct ib_umem	       *umem;
37 	unsigned long		user_virt;
38 	int			refcnt;
39 };
40 
41 int mlx5_ib_db_map_user(struct mlx5_ib_ucontext *context, unsigned long virt,
42 			struct mlx5_db *db)
43 {
44 	struct mlx5_ib_user_db_page *page;
45 	int err = 0;
46 
47 	mutex_lock(&context->db_page_mutex);
48 
49 	list_for_each_entry(page, &context->db_page_list, list)
50 		if (page->user_virt == (virt & PAGE_MASK))
51 			goto found;
52 
53 	page = kmalloc(sizeof(*page), GFP_KERNEL);
54 	if (!page) {
55 		err = -ENOMEM;
56 		goto out;
57 	}
58 
59 	page->user_virt = (virt & PAGE_MASK);
60 	page->refcnt    = 0;
61 	page->umem      = ib_umem_get(&context->ibucontext, virt & PAGE_MASK,
62 				      PAGE_SIZE, 0, 0);
63 	if (IS_ERR(page->umem)) {
64 		err = PTR_ERR(page->umem);
65 		kfree(page);
66 		goto out;
67 	}
68 
69 	list_add(&page->list, &context->db_page_list);
70 
71 found:
72 	db->dma = sg_dma_address(page->umem->sg_head.sgl) + (virt & ~PAGE_MASK);
73 	db->u.user_page = page;
74 	++page->refcnt;
75 
76 out:
77 	mutex_unlock(&context->db_page_mutex);
78 
79 	return err;
80 }
81 
82 void mlx5_ib_db_unmap_user(struct mlx5_ib_ucontext *context, struct mlx5_db *db)
83 {
84 	mutex_lock(&context->db_page_mutex);
85 
86 	if (!--db->u.user_page->refcnt) {
87 		list_del(&db->u.user_page->list);
88 		ib_umem_release(db->u.user_page->umem);
89 		kfree(db->u.user_page);
90 	}
91 
92 	mutex_unlock(&context->db_page_mutex);
93 }
94