doorbell.c

  1/*
  2 * Copyright (c) 2007 Cisco Systems, Inc. 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/slab.h>
 34#include <rdma/uverbs_ioctl.h>
 35
 36#include "mlx4_ib.h"
 37
 38struct mlx4_ib_user_db_page {
 39	struct list_head	list;
 40	struct ib_umem	       *umem;
 41	unsigned long		user_virt;
 42	int			refcnt;
 43};
 44
 45int mlx4_ib_db_map_user(struct ib_udata *udata, unsigned long virt,
 46			struct mlx4_db *db)
 47{
 48	struct mlx4_ib_user_db_page *page;
 49	int err = 0;
 50	struct mlx4_ib_ucontext *context = rdma_udata_to_drv_context(
 51		udata, struct mlx4_ib_ucontext, ibucontext);
 52
 53	mutex_lock(&context->db_page_mutex);
 54
 55	list_for_each_entry(page, &context->db_page_list, list)
 56		if (page->user_virt == (virt & PAGE_MASK))
 57			goto found;
 58
 59	page = kmalloc(sizeof *page, GFP_KERNEL);
 60	if (!page) {
 61		err = -ENOMEM;
 62		goto out;
 63	}
 64
 65	page->user_virt = (virt & PAGE_MASK);
 66	page->refcnt    = 0;
 67	page->umem = ib_umem_get(context->ibucontext.device, virt & PAGE_MASK,
 68				 PAGE_SIZE, 0);
 69	if (IS_ERR(page->umem)) {
 70		err = PTR_ERR(page->umem);
 71		kfree(page);
 72		goto out;
 73	}
 74
 75	list_add(&page->list, &context->db_page_list);
 76
 77found:
 78	db->dma = sg_dma_address(page->umem->sgt_append.sgt.sgl) +
 79		  (virt & ~PAGE_MASK);
 80	db->u.user_page = page;
 81	++page->refcnt;
 82
 83out:
 84	mutex_unlock(&context->db_page_mutex);
 85
 86	return err;
 87}
 88
 89void mlx4_ib_db_unmap_user(struct mlx4_ib_ucontext *context, struct mlx4_db *db)
 90{
 91	mutex_lock(&context->db_page_mutex);
 92
 93	if (!--db->u.user_page->refcnt) {
 94		list_del(&db->u.user_page->list);
 95		ib_umem_release(db->u.user_page->umem);
 96		kfree(db->u.user_page);
 97	}
 98
 99	mutex_unlock(&context->db_page_mutex);
100}