ib_cq.c revision 331769 
1/*
2 * Copyright (c) 2017 Mellanox Technologies Ltd.  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/module.h>
34#include <linux/err.h>
35#include <linux/slab.h>
36
37#include <rdma/ib_verbs.h>
38
39#define	IB_CQ_POLL_MAX	16
40/* maximum number of completions per poll loop */
41#define	IB_CQ_POLL_BUDGET 65536
42#define	IB_CQ_POLL_FLAGS (IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS)
43
44static void
45ib_cq_poll_work(struct work_struct *work)
46{
47	struct ib_wc ib_wc[IB_CQ_POLL_MAX];
48	struct ib_cq *cq = container_of(work, struct ib_cq, work);
49	int total = 0;
50	int i;
51	int n;
52
53	while (1) {
54		n = ib_poll_cq(cq, IB_CQ_POLL_MAX, ib_wc);
55		for (i = 0; i < n; i++) {
56			struct ib_wc *wc = ib_wc + i;
57
58			if (wc->wr_cqe != NULL)
59				wc->wr_cqe->done(cq, wc);
60		}
61
62		if (n != IB_CQ_POLL_MAX) {
63			if (ib_req_notify_cq(cq, IB_CQ_POLL_FLAGS) > 0)
64				break;
65			else
66				return;
67		}
68		total += n;
69		if (total >= IB_CQ_POLL_BUDGET)
70			break;
71	}
72
73	/* give other work structs a chance */
74	queue_work(ib_comp_wq, &cq->work);
75}
76
77static void
78ib_cq_completion_workqueue(struct ib_cq *cq, void *private)
79{
80	queue_work(ib_comp_wq, &cq->work);
81}
82
83struct ib_cq *
84ib_alloc_cq(struct ib_device *dev, void *private,
85    int nr_cqe, int comp_vector, enum ib_poll_context poll_ctx)
86{
87	struct ib_cq_init_attr cq_attr = {
88		.cqe = nr_cqe,
89		.comp_vector = comp_vector,
90	};
91	struct ib_cq *cq;
92
93	/*
94	 * Check for invalid parameters early on to avoid
95	 * extra error handling code:
96	 */
97	switch (poll_ctx) {
98	case IB_POLL_DIRECT:
99	case IB_POLL_SOFTIRQ:
100	case IB_POLL_WORKQUEUE:
101		break;
102	default:
103		return (ERR_PTR(-EINVAL));
104	}
105
106	cq = dev->create_cq(dev, &cq_attr, NULL, NULL);
107	if (IS_ERR(cq))
108		return (cq);
109
110	cq->device = dev;
111	cq->uobject = NULL;
112	cq->event_handler = NULL;
113	cq->cq_context = private;
114	cq->poll_ctx = poll_ctx;
115	atomic_set(&cq->usecnt, 0);
116
117	switch (poll_ctx) {
118	case IB_POLL_DIRECT:
119		cq->comp_handler = NULL;	/* no hardware completions */
120		break;
121	case IB_POLL_SOFTIRQ:
122	case IB_POLL_WORKQUEUE:
123		cq->comp_handler = ib_cq_completion_workqueue;
124		INIT_WORK(&cq->work, ib_cq_poll_work);
125		ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
126		break;
127	default:
128		break;
129	}
130	return (cq);
131}
132EXPORT_SYMBOL(ib_alloc_cq);
133
134void
135ib_free_cq(struct ib_cq *cq)
136{
137
138	if (WARN_ON_ONCE(atomic_read(&cq->usecnt) != 0))
139		return;
140
141	switch (cq->poll_ctx) {
142	case IB_POLL_DIRECT:
143		break;
144	case IB_POLL_SOFTIRQ:
145	case IB_POLL_WORKQUEUE:
146		flush_work(&cq->work);
147		break;
148	default:
149		break;
150	}
151
152	(void)cq->device->destroy_cq(cq);
153}
154EXPORT_SYMBOL(ib_free_cq);
155