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 
40 struct 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 
48 int 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 
81 found:
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 
87 out:
88 	mutex_unlock(&context->db_page_mutex);
89 
90 	return err;
91 }
92 
93 void 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