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nvme-rdma: don't suppress send completions

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The entire completions suppress mechanism is currently broken because the
HCA might retry a send operation (due to dropped ack) after the nvme
transaction has completed.

In order to handle this, we signal all send completions and introduce a
separate done handler for async events as they will be handled differently
(as they don't include in-capsule data by definition).

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
This commit is contained in:
Sagi Grimberg 2017-11-23 17:35:21 +02:00 committed by Christoph Hellwig
parent 6c4ca1e36c
commit b4b591c87f
1 changed files with 14 additions and 40 deletions
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54
drivers/nvme/host/rdma.c
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@ -77,7 +77,6 @@ enum nvme_rdma_queue_flags {
struct nvme_rdma_queue {
struct nvme_rdma_qe *rsp_ring;
atomic_t sig_count;
int queue_size;
size_t cmnd_capsule_len;
struct nvme_rdma_ctrl *ctrl;
@ -510,7 +509,6 @@ static int nvme_rdma_alloc_queue(struct nvme_rdma_ctrl *ctrl,
queue->cmnd_capsule_len = sizeof(struct nvme_command);
queue->queue_size = queue_size;
atomic_set(&queue->sig_count, 0);
queue->cm_id = rdma_create_id(&init_net, nvme_rdma_cm_handler, queue,
RDMA_PS_TCP, IB_QPT_RC);
@ -1204,21 +1202,9 @@ static void nvme_rdma_send_done(struct ib_cq *cq, struct ib_wc *wc)
nvme_rdma_wr_error(cq, wc, "SEND");
}
/*
* We want to signal completion at least every queue depth/2. This returns the
* largest power of two that is not above half of (queue size + 1) to optimize
* (avoid divisions).
*/
static inline bool nvme_rdma_queue_sig_limit(struct nvme_rdma_queue *queue)
{
int limit = 1 << ilog2((queue->queue_size + 1) / 2);
return (atomic_inc_return(&queue->sig_count) & (limit - 1)) == 0;
}
static int nvme_rdma_post_send(struct nvme_rdma_queue *queue,
struct nvme_rdma_qe *qe, struct ib_sge *sge, u32 num_sge,
struct ib_send_wr *first, bool flush)
struct ib_send_wr *first)
{
struct ib_send_wr wr, *bad_wr;
int ret;
@ -1227,31 +1213,12 @@ static int nvme_rdma_post_send(struct nvme_rdma_queue *queue,
sge->length = sizeof(struct nvme_command),
sge->lkey = queue->device->pd->local_dma_lkey;
qe->cqe.done = nvme_rdma_send_done;
wr.next = NULL;
wr.wr_cqe = &qe->cqe;
wr.sg_list = sge;
wr.num_sge = num_sge;
wr.opcode = IB_WR_SEND;
wr.send_flags = 0;
/*
* Unsignalled send completions are another giant desaster in the
* IB Verbs spec: If we don't regularly post signalled sends
* the send queue will fill up and only a QP reset will rescue us.
* Would have been way to obvious to handle this in hardware or
* at least the RDMA stack..
*
* Always signal the flushes. The magic request used for the flush
* sequencer is not allocated in our driver's tagset and it's
* triggered to be freed by blk_cleanup_queue(). So we need to
* always mark it as signaled to ensure that the "wr_cqe", which is
* embedded in request's payload, is not freed when __ib_process_cq()
* calls wr_cqe->done().
*/
if (nvme_rdma_queue_sig_limit(queue) || flush)
wr.send_flags |= IB_SEND_SIGNALED;
wr.send_flags = IB_SEND_SIGNALED;
if (first)
first->next = &wr;
@ -1301,6 +1268,12 @@ static struct blk_mq_tags *nvme_rdma_tagset(struct nvme_rdma_queue *queue)
return queue->ctrl->tag_set.tags[queue_idx - 1];
}
static void nvme_rdma_async_done(struct ib_cq *cq, struct ib_wc *wc)
{
if (unlikely(wc->status != IB_WC_SUCCESS))
nvme_rdma_wr_error(cq, wc, "ASYNC");
}
static void nvme_rdma_submit_async_event(struct nvme_ctrl *arg)
{
struct nvme_rdma_ctrl *ctrl = to_rdma_ctrl(arg);
@ -1319,10 +1292,12 @@ static void nvme_rdma_submit_async_event(struct nvme_ctrl *arg)
cmd->common.flags |= NVME_CMD_SGL_METABUF;
nvme_rdma_set_sg_null(cmd);
sqe->cqe.done = nvme_rdma_async_done;
ib_dma_sync_single_for_device(dev, sqe->dma, sizeof(*cmd),
DMA_TO_DEVICE);
ret = nvme_rdma_post_send(queue, sqe, &sge, 1, NULL, false);
ret = nvme_rdma_post_send(queue, sqe, &sge, 1, NULL);
WARN_ON_ONCE(ret);
}
@ -1607,7 +1582,6 @@ static blk_status_t nvme_rdma_queue_rq(struct blk_mq_hw_ctx *hctx,
struct nvme_rdma_request *req = blk_mq_rq_to_pdu(rq);
struct nvme_rdma_qe *sqe = &req->sqe;
struct nvme_command *c = sqe->data;
bool flush = false;
struct ib_device *dev;
blk_status_t ret;
int err;
@ -1636,13 +1610,13 @@ static blk_status_t nvme_rdma_queue_rq(struct blk_mq_hw_ctx *hctx,
goto err;
}
sqe->cqe.done = nvme_rdma_send_done;
ib_dma_sync_single_for_device(dev, sqe->dma,
sizeof(struct nvme_command), DMA_TO_DEVICE);
if (req_op(rq) == REQ_OP_FLUSH)
flush = true;
err = nvme_rdma_post_send(queue, sqe, req->sge, req->num_sge,
req->mr->need_inval ? &req->reg_wr.wr : NULL, flush);
req->mr->need_inval ? &req->reg_wr.wr : NULL);
if (unlikely(err)) {
nvme_rdma_unmap_data(queue, rq);
goto err;