lkml.org 
[lkml]   [2018]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.14 110/110] nvme-rdma: dont suppress send completions
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Sagi Grimberg <sagi@grimberg.me>

commit b4b591c87f2b0f4ebaf3a68d4f13873b241aa584 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


---
drivers/nvme/host/rdma.c | 54 ++++++++++++-----------------------------------
1 file changed, 14 insertions(+), 40 deletions(-)

--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -88,7 +88,6 @@ 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;
@@ -521,7 +520,6 @@ static int nvme_rdma_alloc_queue(struct
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);
@@ -1232,21 +1230,9 @@ static void nvme_rdma_send_done(struct i
nvme_end_request(rq, req->status, req->result);
}

-/*
- * 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;
@@ -1255,31 +1241,12 @@ static int nvme_rdma_post_send(struct nv
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;
@@ -1329,6 +1296,12 @@ static struct blk_mq_tags *nvme_rdma_tag
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, int aer_idx)
{
struct nvme_rdma_ctrl *ctrl = to_rdma_ctrl(arg);
@@ -1350,10 +1323,12 @@ static void nvme_rdma_submit_async_event
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);
}

@@ -1639,7 +1614,6 @@ static blk_status_t nvme_rdma_queue_rq(s
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;
@@ -1668,13 +1642,13 @@ static blk_status_t nvme_rdma_queue_rq(s
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;

\
 
 \ /
  Last update: 2018-03-07 20:51    [W:0.370 / U:3.032 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site