drivers/infiniband/core/cq.c

   1 /*
   2  * Copyright (c) 2015 HGST, a Western Digital Company.
   3  *
   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.
   7  *
   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
  11  * more details.
  12  */
  13 #include <linux/module.h>
  14 #include <linux/err.h>
  15 #include <linux/slab.h>
  16 #include <rdma/ib_verbs.h>
  17
  18 /* # of WCs to poll for with a single call to ib_poll_cq */
  19 #define IB_POLL_BATCH                   16
  20 #define IB_POLL_BATCH_DIRECT            8
  21
  22 /* # of WCs to iterate over before yielding */
  23 #define IB_POLL_BUDGET_IRQ              256
  24 #define IB_POLL_BUDGET_WORKQUEUE        65536
  25
  26 #define IB_POLL_FLAGS \
  27         (IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS)
  28
  29 static int __ib_process_cq(struct ib_cq *cq, int budget, struct ib_wc *wcs,
  30                            int batch)
  31 {
  32         int i, n, completed = 0;
  33
  34         /*
  35          * budget might be (-1) if the caller does not
  36          * want to bound this call, thus we need unsigned
  37          * minimum here.
  38          */
  39         while ((n = ib_poll_cq(cq, min_t(u32, batch,
  40                                          budget - completed), wcs)) > 0) {
  41                 for (i = 0; i < n; i++) {
  42                         struct ib_wc *wc = &wcs[i];
  43
  44                         if (wc->wr_cqe)
  45                                 wc->wr_cqe->done(cq, wc);
  46                         else
  47                                 WARN_ON_ONCE(wc->status == IB_WC_SUCCESS);
  48                 }
  49
  50                 completed += n;
  51
  52                 if (n != batch || (budget != -1 && completed >= budget))
  53                         break;
  54         }
  55
  56         return completed;
  57 }
  58
  59 /**
  60  * ib_process_direct_cq - process a CQ in caller context
  61  * @cq:         CQ to process
  62  * @budget:     number of CQEs to poll for
  63  *
  64  * This function is used to process all outstanding CQ entries.
  65  * It does not offload CQ processing to a different context and does
  66  * not ask for completion interrupts from the HCA.
  67  * Using direct processing on CQ with non IB_POLL_DIRECT type may trigger
  68  * concurrent processing.
  69  *
  70  * Note: do not pass -1 as %budget unless it is guaranteed that the number
  71  * of completions that will be processed is small.
  72  */
  73 int ib_process_cq_direct(struct ib_cq *cq, int budget)
  74 {
  75         struct ib_wc wcs[IB_POLL_BATCH_DIRECT];
  76
  77         return __ib_process_cq(cq, budget, wcs, IB_POLL_BATCH_DIRECT);
  78 }
  79 EXPORT_SYMBOL(ib_process_cq_direct);
  80
  81 static void ib_cq_completion_direct(struct ib_cq *cq, void *private)
  82 {
  83         WARN_ONCE(1, "got unsolicited completion for CQ 0x%p\n", cq);
  84 }
  85
  86 static int ib_poll_handler(struct irq_poll *iop, int budget)
  87 {
  88         struct ib_cq *cq = container_of(iop, struct ib_cq, iop);
  89         int completed;
  90
  91         completed = __ib_process_cq(cq, budget, cq->wc, IB_POLL_BATCH);
  92         if (completed < budget) {
  93                 irq_poll_complete(&cq->iop);
  94                 if (ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
  95                         irq_poll_sched(&cq->iop);
  96         }
  97
  98         return completed;
  99 }
 100
 101 static void ib_cq_completion_softirq(struct ib_cq *cq, void *private)
 102 {
 103         irq_poll_sched(&cq->iop);
 104 }
 105
 106 static void ib_cq_poll_work(struct work_struct *work)
 107 {
 108         struct ib_cq *cq = container_of(work, struct ib_cq, work);
 109         int completed;
 110
 111         completed = __ib_process_cq(cq, IB_POLL_BUDGET_WORKQUEUE, cq->wc,
 112                                     IB_POLL_BATCH);
 113         if (completed >= IB_POLL_BUDGET_WORKQUEUE ||
 114             ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
 115                 queue_work(ib_comp_wq, &cq->work);
 116 }
 117
 118 static void ib_cq_completion_workqueue(struct ib_cq *cq, void *private)
 119 {
 120         queue_work(ib_comp_wq, &cq->work);
 121 }
 122
 123 /**
 124  * __ib_alloc_cq - allocate a completion queue
 125  * @dev:                device to allocate the CQ for
 126  * @private:            driver private data, accessible from cq->cq_context
 127  * @nr_cqe:             number of CQEs to allocate
 128  * @comp_vector:        HCA completion vectors for this CQ
 129  * @poll_ctx:           context to poll the CQ from.
 130  * @caller:             module owner name.
 131  *
 132  * This is the proper interface to allocate a CQ for in-kernel users. A
 133  * CQ allocated with this interface will automatically be polled from the
 134  * specified context. The ULP must use wr->wr_cqe instead of wr->wr_id
 135  * to use this CQ abstraction.
 136  */
 137 struct ib_cq *__ib_alloc_cq(struct ib_device *dev, void *private,
 138                             int nr_cqe, int comp_vector,
 139                             enum ib_poll_context poll_ctx, const char *caller)
 140 {
 141         struct ib_cq_init_attr cq_attr = {
 142                 .cqe            = nr_cqe,
 143                 .comp_vector    = comp_vector,
 144         };
 145         struct ib_cq *cq;
 146         int ret = -ENOMEM;
 147
 148         cq = dev->create_cq(dev, &cq_attr, NULL, NULL);
 149         if (IS_ERR(cq))
 150                 return cq;
 151
 152         cq->device = dev;
 153         cq->uobject = NULL;
 154         cq->event_handler = NULL;
 155         cq->cq_context = private;
 156         cq->poll_ctx = poll_ctx;
 157         atomic_set(&cq->usecnt, 0);
 158
 159         cq->wc = kmalloc_array(IB_POLL_BATCH, sizeof(*cq->wc), GFP_KERNEL);
 160         if (!cq->wc)
 161                 goto out_destroy_cq;
 162
 163         cq->res.type = RDMA_RESTRACK_CQ;
 164         cq->res.kern_name = caller;
 165         rdma_restrack_add(&cq->res);
 166
 167         switch (cq->poll_ctx) {
 168         case IB_POLL_DIRECT:
 169                 cq->comp_handler = ib_cq_completion_direct;
 170                 break;
 171         case IB_POLL_SOFTIRQ:
 172                 cq->comp_handler = ib_cq_completion_softirq;
 173
 174                 irq_poll_init(&cq->iop, IB_POLL_BUDGET_IRQ, ib_poll_handler);
 175                 ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
 176                 break;
 177         case IB_POLL_WORKQUEUE:
 178                 cq->comp_handler = ib_cq_completion_workqueue;
 179                 INIT_WORK(&cq->work, ib_cq_poll_work);
 180                 ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
 181                 break;
 182         default:
 183                 ret = -EINVAL;
 184                 goto out_free_wc;
 185         }
 186
 187         return cq;
 188
 189 out_free_wc:
 190         kfree(cq->wc);
 191         rdma_restrack_del(&cq->res);
 192 out_destroy_cq:
 193         cq->device->destroy_cq(cq);
 194         return ERR_PTR(ret);
 195 }
 196 EXPORT_SYMBOL(__ib_alloc_cq);
 197
 198 /**
 199  * ib_free_cq - free a completion queue
 200  * @cq:         completion queue to free.
 201  */
 202 void ib_free_cq(struct ib_cq *cq)
 203 {
 204         int ret;
 205
 206         if (WARN_ON_ONCE(atomic_read(&cq->usecnt)))
 207                 return;
 208
 209         switch (cq->poll_ctx) {
 210         case IB_POLL_DIRECT:
 211                 break;
 212         case IB_POLL_SOFTIRQ:
 213                 irq_poll_disable(&cq->iop);
 214                 break;
 215         case IB_POLL_WORKQUEUE:
 216                 cancel_work_sync(&cq->work);
 217                 break;
 218         default:
 219                 WARN_ON_ONCE(1);
 220         }
 221
 222         kfree(cq->wc);
 223         rdma_restrack_del(&cq->res);
 224         ret = cq->device->destroy_cq(cq);
 225         WARN_ON_ONCE(ret);
 226 }
 227 EXPORT_SYMBOL(ib_free_cq);