2 * Copyright (c) 2015 HGST, a Western Digital Company.
4 * This program is free software; you can redistribute it and/or modify it
5 * under the terms and conditions of the GNU General Public License,
6 * version 2, as published by the Free Software Foundation.
8 * This program is distributed in the hope it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
13 #include <linux/module.h>
14 #include <linux/err.h>
15 #include <linux/slab.h>
16 #include <rdma/ib_verbs.h>
18 /* # of WCs to poll for with a single call to ib_poll_cq */
19 #define IB_POLL_BATCH 16
21 /* # of WCs to iterate over before yielding */
22 #define IB_POLL_BUDGET_IRQ 256
23 #define IB_POLL_BUDGET_WORKQUEUE 65536
25 #define IB_POLL_FLAGS \
26 (IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS)
28 static int __ib_process_cq(struct ib_cq *cq, int budget)
30 int i, n, completed = 0;
33 * budget might be (-1) if the caller does not
34 * want to bound this call, thus we need unsigned
37 while ((n = ib_poll_cq(cq, min_t(u32, IB_POLL_BATCH,
38 budget - completed), cq->wc)) > 0) {
39 for (i = 0; i < n; i++) {
40 struct ib_wc *wc = &cq->wc[i];
43 wc->wr_cqe->done(cq, wc);
45 WARN_ON_ONCE(wc->status == IB_WC_SUCCESS);
50 if (n != IB_POLL_BATCH ||
51 (budget != -1 && completed >= budget))
59 * ib_process_direct_cq - process a CQ in caller context
61 * @budget: number of CQEs to poll for
63 * This function is used to process all outstanding CQ entries on a
64 * %IB_POLL_DIRECT CQ. It does not offload CQ processing to a different
65 * context and does not ask for completion interrupts from the HCA.
67 * Note: do not pass -1 as %budget unless it is guaranteed that the number
68 * of completions that will be processed is small.
70 int ib_process_cq_direct(struct ib_cq *cq, int budget)
72 WARN_ON_ONCE(cq->poll_ctx != IB_POLL_DIRECT);
74 return __ib_process_cq(cq, budget);
76 EXPORT_SYMBOL(ib_process_cq_direct);
78 static void ib_cq_completion_direct(struct ib_cq *cq, void *private)
80 WARN_ONCE(1, "got unsolicited completion for CQ 0x%p\n", cq);
83 static int ib_poll_handler(struct irq_poll *iop, int budget)
85 struct ib_cq *cq = container_of(iop, struct ib_cq, iop);
88 completed = __ib_process_cq(cq, budget);
89 if (completed < budget) {
90 irq_poll_complete(&cq->iop);
91 if (ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
92 irq_poll_sched(&cq->iop);
98 static void ib_cq_completion_softirq(struct ib_cq *cq, void *private)
100 irq_poll_sched(&cq->iop);
103 static void ib_cq_poll_work(struct work_struct *work)
105 struct ib_cq *cq = container_of(work, struct ib_cq, work);
108 completed = __ib_process_cq(cq, IB_POLL_BUDGET_WORKQUEUE);
109 if (completed >= IB_POLL_BUDGET_WORKQUEUE ||
110 ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
111 queue_work(ib_comp_wq, &cq->work);
114 static void ib_cq_completion_workqueue(struct ib_cq *cq, void *private)
116 queue_work(ib_comp_wq, &cq->work);
120 * ib_alloc_cq - allocate a completion queue
121 * @dev: device to allocate the CQ for
122 * @private: driver private data, accessible from cq->cq_context
123 * @nr_cqe: number of CQEs to allocate
124 * @comp_vector: HCA completion vectors for this CQ
125 * @poll_ctx: context to poll the CQ from.
127 * This is the proper interface to allocate a CQ for in-kernel users. A
128 * CQ allocated with this interface will automatically be polled from the
129 * specified context. The ULP must use wr->wr_cqe instead of wr->wr_id
130 * to use this CQ abstraction.
132 struct ib_cq *ib_alloc_cq(struct ib_device *dev, void *private,
133 int nr_cqe, int comp_vector, enum ib_poll_context poll_ctx)
135 struct ib_cq_init_attr cq_attr = {
137 .comp_vector = comp_vector,
142 cq = dev->create_cq(dev, &cq_attr, NULL, NULL);
148 cq->event_handler = NULL;
149 cq->cq_context = private;
150 cq->poll_ctx = poll_ctx;
151 atomic_set(&cq->usecnt, 0);
153 cq->wc = kmalloc_array(IB_POLL_BATCH, sizeof(*cq->wc), GFP_KERNEL);
157 switch (cq->poll_ctx) {
159 cq->comp_handler = ib_cq_completion_direct;
161 case IB_POLL_SOFTIRQ:
162 cq->comp_handler = ib_cq_completion_softirq;
164 irq_poll_init(&cq->iop, IB_POLL_BUDGET_IRQ, ib_poll_handler);
165 ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
167 case IB_POLL_WORKQUEUE:
168 cq->comp_handler = ib_cq_completion_workqueue;
169 INIT_WORK(&cq->work, ib_cq_poll_work);
170 ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
182 cq->device->destroy_cq(cq);
185 EXPORT_SYMBOL(ib_alloc_cq);
188 * ib_free_cq - free a completion queue
189 * @cq: completion queue to free.
191 void ib_free_cq(struct ib_cq *cq)
195 if (WARN_ON_ONCE(atomic_read(&cq->usecnt)))
198 switch (cq->poll_ctx) {
201 case IB_POLL_SOFTIRQ:
202 irq_poll_disable(&cq->iop);
204 case IB_POLL_WORKQUEUE:
205 cancel_work_sync(&cq->work);
212 ret = cq->device->destroy_cq(cq);
215 EXPORT_SYMBOL(ib_free_cq);