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/*
* Copyright (c) 2015 HGST, a Western Digital Company.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*/
#include <linux/module.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <rdma/ib_verbs.h>
/* # of WCs to poll for with a single call to ib_poll_cq */
#define IB_POLL_BATCH 16
/* # of WCs to iterate over before yielding */
#define IB_POLL_BUDGET_IRQ 256
#define IB_POLL_BUDGET_WORKQUEUE 65536
#define IB_POLL_FLAGS \
(IB_CQ_NEXT_COMP | IB_CQ_REPORT_MISSED_EVENTS)
static int __ib_process_cq(struct ib_cq *cq, int budget)
{
int i, n, completed = 0;
/*
* budget might be (-1) if the caller does not
* want to bound this call, thus we need unsigned
* minimum here.
*/
while ((n = ib_poll_cq(cq, min_t(u32, IB_POLL_BATCH,
budget - completed), cq->wc)) > 0) {
for (i = 0; i < n; i++) {
struct ib_wc *wc = &cq->wc[i];
if (wc->wr_cqe)
wc->wr_cqe->done(cq, wc);
else
WARN_ON_ONCE(wc->status == IB_WC_SUCCESS);
}
completed += n;
if (n != IB_POLL_BATCH ||
(budget != -1 && completed >= budget))
break;
}
return completed;
}
/**
* ib_process_direct_cq - process a CQ in caller context
* @cq: CQ to process
* @budget: number of CQEs to poll for
*
* This function is used to process all outstanding CQ entries on a
* %IB_POLL_DIRECT CQ. It does not offload CQ processing to a different
* context and does not ask for completion interrupts from the HCA.
*
* Note: do not pass -1 as %budget unless it is guaranteed that the number
* of completions that will be processed is small.
*/
int ib_process_cq_direct(struct ib_cq *cq, int budget)
{
WARN_ON_ONCE(cq->poll_ctx != IB_POLL_DIRECT);
return __ib_process_cq(cq, budget);
}
EXPORT_SYMBOL(ib_process_cq_direct);
static void ib_cq_completion_direct(struct ib_cq *cq, void *private)
{
WARN_ONCE(1, "got unsolicited completion for CQ 0x%p\n", cq);
}
static int ib_poll_handler(struct irq_poll *iop, int budget)
{
struct ib_cq *cq = container_of(iop, struct ib_cq, iop);
int completed;
completed = __ib_process_cq(cq, budget);
if (completed < budget) {
irq_poll_complete(&cq->iop);
if (ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
irq_poll_sched(&cq->iop);
}
return completed;
}
static void ib_cq_completion_softirq(struct ib_cq *cq, void *private)
{
irq_poll_sched(&cq->iop);
}
static void ib_cq_poll_work(struct work_struct *work)
{
struct ib_cq *cq = container_of(work, struct ib_cq, work);
int completed;
completed = __ib_process_cq(cq, IB_POLL_BUDGET_WORKQUEUE);
if (completed >= IB_POLL_BUDGET_WORKQUEUE ||
ib_req_notify_cq(cq, IB_POLL_FLAGS) > 0)
queue_work(ib_comp_wq, &cq->work);
}
static void ib_cq_completion_workqueue(struct ib_cq *cq, void *private)
{
queue_work(ib_comp_wq, &cq->work);
}
/**
* ib_alloc_cq - allocate a completion queue
* @dev: device to allocate the CQ for
* @private: driver private data, accessible from cq->cq_context
* @nr_cqe: number of CQEs to allocate
* @comp_vector: HCA completion vectors for this CQ
* @poll_ctx: context to poll the CQ from.
*
* This is the proper interface to allocate a CQ for in-kernel users. A
* CQ allocated with this interface will automatically be polled from the
* specified context. The ULP must use wr->wr_cqe instead of wr->wr_id
* to use this CQ abstraction.
*/
struct ib_cq *ib_alloc_cq(struct ib_device *dev, void *private,
int nr_cqe, int comp_vector, enum ib_poll_context poll_ctx)
{
struct ib_cq_init_attr cq_attr = {
.cqe = nr_cqe,
.comp_vector = comp_vector,
};
struct ib_cq *cq;
int ret = -ENOMEM;
cq = dev->create_cq(dev, &cq_attr, NULL, NULL);
if (IS_ERR(cq))
return cq;
cq->device = dev;
cq->uobject = NULL;
cq->event_handler = NULL;
cq->cq_context = private;
cq->poll_ctx = poll_ctx;
atomic_set(&cq->usecnt, 0);
cq->wc = kmalloc_array(IB_POLL_BATCH, sizeof(*cq->wc), GFP_KERNEL);
if (!cq->wc)
goto out_destroy_cq;
switch (cq->poll_ctx) {
case IB_POLL_DIRECT:
cq->comp_handler = ib_cq_completion_direct;
break;
case IB_POLL_SOFTIRQ:
cq->comp_handler = ib_cq_completion_softirq;
irq_poll_init(&cq->iop, IB_POLL_BUDGET_IRQ, ib_poll_handler);
ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
break;
case IB_POLL_WORKQUEUE:
cq->comp_handler = ib_cq_completion_workqueue;
INIT_WORK(&cq->work, ib_cq_poll_work);
ib_req_notify_cq(cq, IB_CQ_NEXT_COMP);
break;
default:
ret = -EINVAL;
goto out_free_wc;
}
return cq;
out_free_wc:
kfree(cq->wc);
out_destroy_cq:
cq->device->destroy_cq(cq);
return ERR_PTR(ret);
}
EXPORT_SYMBOL(ib_alloc_cq);
/**
* ib_free_cq - free a completion queue
* @cq: completion queue to free.
*/
void ib_free_cq(struct ib_cq *cq)
{
int ret;
if (WARN_ON_ONCE(atomic_read(&cq->usecnt)))
return;
switch (cq->poll_ctx) {
case IB_POLL_DIRECT:
break;
case IB_POLL_SOFTIRQ:
irq_poll_disable(&cq->iop);
break;
case IB_POLL_WORKQUEUE:
cancel_work_sync(&cq->work);
break;
default:
WARN_ON_ONCE(1);
}
kfree(cq->wc);
ret = cq->device->destroy_cq(cq);
WARN_ON_ONCE(ret);
}
EXPORT_SYMBOL(ib_free_cq);
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