[PATCH v8 for-next 0/2] Add the workqueue framework for flush cqe handler

[PATCH v8 for-next 0/2] Add the workqueue framework for flush cqe handler

[Yixian Liu]

Earlier Background:
HiP08 RoCE hardware lacks ability(a known hardware problem) to flush
outstanding WQEs if QP state gets into errored mode for some reason.
To overcome this hardware problem and as a workaround, when QP is
detected to be in errored state during various legs like post send,
post receive etc [1], flush needs to be performed from the driver.

These data-path legs might get called concurrently from various context,
like thread and interrupt as well (like NVMe driver). Hence, these need
to be protected with spin-locks for the concurrency. This code exists
within the driver.

Problem:
Earlier The patch[1] sent to solve the hardware limitation explained
in the background section had a bug in the software flushing leg. It
acquired mutex while modifying QP state to errored state and while
conveying it to the hardware using the mailbox. This caused leg to
sleep while holding spin-lock and caused crash.

Suggested Solution:
In this patch, we have proposed to defer the flushing of the QP in
Errored state using the workqueue.

We do understand that this might have an impact on the recovery times
as scheduling of the workqueue handler depends upon the occupancy of
the system. Therefore to roughly mitigate this affect we have tried
to use Concurrency Managed workqueue to give worker thread (and
hence handler) a chance to run over more than one core.


[1] https://patchwork.kernel.org/patch/10534271/


This patch-set consists of:
[Patch 001] Introduce workqueue based WQE Flush Handler
[Patch 002] Call WQE flush handler in post {send|receive|poll}

v8 changes:
1. Use flag instead of counter for initializing flush work accroding
   to Jason's suggestion.

v7 changes:
1. Delete unnecessary allocation of flush_work and do flush operation
   in flush handle function as needed according to Jason's suggestion.

v6 changes:
1. Holding lock when updating or referencing the flag being_push
   according to Jason's comment, i.e., fix the lock holding in
   hns_roce_v2_modify_qp and hns_roce_v2_poll_one.

v5 changes:
1. Remove WQ_MEM_RECLAIM flag according to Leon's suggestion.
2. Change to ordered workqueue for the requirement of flush work.

v4 changes:
1. Add flag for PI is being pushed according to Jason's suggestion
   to reduce unnecessary works submitted to workqueue.

v3 changes:
1. Fall back to dynamically allocate flush_work.

v2 changes:
1. Remove new created workqueue according to Jason's comment
2. Remove dynamic allocation for flush_work according to Jason's comment
3. Change current irq singlethread workqueue to concurrency management
   workqueue to ensure work unblocked.

Yixian Liu (2):
  RDMA/hns: Add the workqueue framework for flush cqe handler
  RDMA/hns: Delayed flush cqe process with workqueue

 drivers/infiniband/hw/hns/hns_roce_device.h |  26 ++++---
 drivers/infiniband/hw/hns/hns_roce_hw_v2.c  | 102 +++++++++++++++-------------
 drivers/infiniband/hw/hns/hns_roce_qp.c     |  40 +++++++++++
 3 files changed, 111 insertions(+), 57 deletions(-)

-- 
2.7.4

[PATCH v8 for-next 1/2] RDMA/hns: Add the workqueue framework for flush cqe handler

[Yixian Liu]

HiP08 RoCE hardware lacks ability(a known hardware problem) to flush
outstanding WQEs if QP state gets into errored mode for some reason.
To overcome this hardware problem and as a workaround, when QP is
detected to be in errored state during various legs like post send,
post receive etc [1], flush needs to be performed from the driver.

The earlier patch[1] sent to solve the hardware limitation explained
in the cover-letter had a bug in the software flushing leg. It
acquired mutex while modifying QP state to errored state and while
conveying it to the hardware using the mailbox. This caused leg to
sleep while holding spin-lock and caused crash.

Suggested Solution:
we have proposed to defer the flushing of the QP in the Errored state
using the workqueue to get around with the limitation of our hardware.

This patch adds the framework of the workqueue and the flush handler
function.

[1] https://patchwork.kernel.org/patch/10534271/

Signed-off-by: Yixian Liu <liuyixian@huawei.com>
Reviewed-by: Salil Mehta <salil.mehta@huawei.com>
---
 drivers/infiniband/hw/hns/hns_roce_device.h | 20 +++++++++-------
 drivers/infiniband/hw/hns/hns_roce_hw_v2.c  |  3 +--
 drivers/infiniband/hw/hns/hns_roce_qp.c     | 37 +++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+), 11 deletions(-)

diff --git a/drivers/infiniband/hw/hns/hns_roce_device.h b/drivers/infiniband/hw/hns/hns_roce_device.h
index a7c4ff9..a089d47 100644
--- a/drivers/infiniband/hw/hns/hns_roce_device.h
+++ b/drivers/infiniband/hw/hns/hns_roce_device.h
@@ -641,6 +641,15 @@ struct hns_roce_rinl_buf {
 	u32			 wqe_cnt;
 };
 
+struct hns_roce_work {
+	struct hns_roce_dev *hr_dev;
+	struct work_struct work;
+	u32 qpn;
+	u32 cqn;
+	int event_type;
+	int sub_type;
+};
+
 struct hns_roce_qp {
 	struct ib_qp		ibqp;
 	struct hns_roce_buf	hr_buf;
@@ -684,6 +693,7 @@ struct hns_roce_qp {
 	struct hns_roce_sge	sge;
 	u32			next_sge;
 
+	struct hns_roce_work	flush_work;
 	struct hns_roce_rinl_buf rq_inl_buf;
 	struct list_head	node;		/* all qps are on a list */
 	struct list_head	rq_node;	/* all recv qps are on a list */
@@ -906,15 +916,6 @@ struct hns_roce_caps {
 	u16		default_ceq_arm_st;
 };
 
-struct hns_roce_work {
-	struct hns_roce_dev *hr_dev;
-	struct work_struct work;
-	u32 qpn;
-	u32 cqn;
-	int event_type;
-	int sub_type;
-};
-
 struct hns_roce_dfx_hw {
 	int (*query_cqc_info)(struct hns_roce_dev *hr_dev, u32 cqn,
 			      int *buffer);
@@ -1237,6 +1238,7 @@ struct ib_qp *hns_roce_create_qp(struct ib_pd *ib_pd,
 				 struct ib_udata *udata);
 int hns_roce_modify_qp(struct ib_qp *ibqp, struct ib_qp_attr *attr,
 		       int attr_mask, struct ib_udata *udata);
+void init_flush_work(struct hns_roce_dev *hr_dev, struct hns_roce_qp *hr_qp);
 void *get_recv_wqe(struct hns_roce_qp *hr_qp, int n);
 void *get_send_wqe(struct hns_roce_qp *hr_qp, int n);
 void *get_send_extend_sge(struct hns_roce_qp *hr_qp, int n);
diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
index 12c4cd8..950c604 100644
--- a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
+++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
@@ -6292,8 +6292,7 @@ static int hns_roce_v2_init_eq_table(struct hns_roce_dev *hr_dev)
 		goto err_request_irq_fail;
 	}
 
-	hr_dev->irq_workq =
-		create_singlethread_workqueue("hns_roce_irq_workqueue");
+	hr_dev->irq_workq = alloc_ordered_workqueue("hns_roce_irq_workq", 0);
 	if (!hr_dev->irq_workq) {
 		dev_err(dev, "Create irq workqueue failed!\n");
 		ret = -ENOMEM;
diff --git a/drivers/infiniband/hw/hns/hns_roce_qp.c b/drivers/infiniband/hw/hns/hns_roce_qp.c
index 3257ad1..dab7314 100644
--- a/drivers/infiniband/hw/hns/hns_roce_qp.c
+++ b/drivers/infiniband/hw/hns/hns_roce_qp.c
@@ -43,6 +43,43 @@
 
 #define SQP_NUM				(2 * HNS_ROCE_MAX_PORTS)
 
+static void flush_work_handle(struct work_struct *work)
+{
+	struct hns_roce_work *flush_work = container_of(work,
+					struct hns_roce_work, work);
+	struct hns_roce_qp *hr_qp = container_of(flush_work,
+					struct hns_roce_qp, flush_work);
+	struct device *dev = flush_work->hr_dev->dev;
+	struct ib_qp_attr attr;
+	int attr_mask;
+	int ret;
+
+	attr_mask = IB_QP_STATE;
+	attr.qp_state = IB_QPS_ERR;
+
+	ret = hns_roce_modify_qp(&hr_qp->ibqp, &attr, attr_mask, NULL);
+	if (ret)
+		dev_err(dev, "Modify QP to error state failed(%d) during CQE flush\n",
+			ret);
+
+	/*
+	 * make sure we signal QP destroy leg that flush QP was completed
+	 * so that it can safely proceed ahead now and destroy QP
+	 */
+	if (atomic_dec_and_test(&hr_qp->refcount))
+		complete(&hr_qp->free);
+}
+
+void init_flush_work(struct hns_roce_dev *hr_dev, struct hns_roce_qp *hr_qp)
+{
+	struct hns_roce_work *flush_work = &hr_qp->flush_work;
+
+	flush_work->hr_dev = hr_dev;
+	INIT_WORK(&flush_work->work, flush_work_handle);
+	atomic_inc(&hr_qp->refcount);
+	queue_work(hr_dev->irq_workq, &flush_work->work);
+}
+
 void hns_roce_qp_event(struct hns_roce_dev *hr_dev, u32 qpn, int event_type)
 {
 	struct device *dev = hr_dev->dev;
-- 
2.7.4

[PATCH v8 for-next 2/2] RDMA/hns: Delayed flush cqe process with workqueue

[Yixian Liu]

HiP08 RoCE hardware lacks ability(a known hardware problem) to flush
outstanding WQEs if QP state gets into errored mode for some reason.
To overcome this hardware problem and as a workaround, when QP is
detected to be in errored state during various legs like post send,
post receive etc[1], flush needs to be performed from the driver.

The earlier patch[1] sent to solve the hardware limitation explained
in the cover-letter had a bug in the software flushing leg. It
acquired mutex while modifying QP state to errored state and while
conveying it to the hardware using the mailbox. This caused leg to
sleep while holding spin-lock and caused crash.

Suggested Solution:
we have proposed to defer the flushing of the QP in the Errored state
using the workqueue to get around with the limitation of our hardware.

This patch specifically adds the calls to the flush handler from
where parts of the code like post_send/post_recv etc. when the QP
state gets into the errored mode.

[1] https://patchwork.kernel.org/patch/10534271/

Signed-off-by: Yixian Liu <liuyixian@huawei.com>
Reviewed-by: Salil Mehta <salil.mehta@huawei.com>
---
 drivers/infiniband/hw/hns/hns_roce_device.h |  6 ++
 drivers/infiniband/hw/hns/hns_roce_hw_v2.c  | 99 +++++++++++++++--------------
 drivers/infiniband/hw/hns/hns_roce_qp.c     | 11 ++--
 3 files changed, 66 insertions(+), 50 deletions(-)

diff --git a/drivers/infiniband/hw/hns/hns_roce_device.h b/drivers/infiniband/hw/hns/hns_roce_device.h
index a089d47..96d7bfa 100644
--- a/drivers/infiniband/hw/hns/hns_roce_device.h
+++ b/drivers/infiniband/hw/hns/hns_roce_device.h
@@ -641,6 +641,10 @@ struct hns_roce_rinl_buf {
 	u32			 wqe_cnt;
 };
 
+enum {
+	HNS_ROCE_FLUSH_FLAG = 0,
+};
+
 struct hns_roce_work {
 	struct hns_roce_dev *hr_dev;
 	struct work_struct work;
@@ -693,6 +697,8 @@ struct hns_roce_qp {
 	struct hns_roce_sge	sge;
 	u32			next_sge;
 
+	/* 0: flush needed, 1: unneeded */
+	unsigned long		flush_flag;
 	struct hns_roce_work	flush_work;
 	struct hns_roce_rinl_buf rq_inl_buf;
 	struct list_head	node;		/* all qps are on a list */
diff --git a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
index 950c604..d33d9eb 100644
--- a/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
+++ b/drivers/infiniband/hw/hns/hns_roce_hw_v2.c
@@ -220,11 +220,6 @@ static int set_rwqe_data_seg(struct ib_qp *ibqp, const struct ib_send_wr *wr,
 	return 0;
 }
 
-static int hns_roce_v2_modify_qp(struct ib_qp *ibqp,
-				 const struct ib_qp_attr *attr,
-				 int attr_mask, enum ib_qp_state cur_state,
-				 enum ib_qp_state new_state);
-
 static int check_send_valid(struct hns_roce_dev *hr_dev,
 			    struct hns_roce_qp *hr_qp)
 {
@@ -261,7 +256,6 @@ static int hns_roce_v2_post_send(struct ib_qp *ibqp,
 	struct hns_roce_wqe_frmr_seg *fseg;
 	struct device *dev = hr_dev->dev;
 	struct hns_roce_v2_db sq_db;
-	struct ib_qp_attr attr;
 	unsigned int owner_bit;
 	unsigned int sge_idx;
 	unsigned int wqe_idx;
@@ -269,7 +263,6 @@ static int hns_roce_v2_post_send(struct ib_qp *ibqp,
 	int valid_num_sge;
 	void *wqe = NULL;
 	bool loopback;
-	int attr_mask;
 	u32 tmp_len;
 	u32 hr_op;
 	u8 *smac;
@@ -607,18 +600,19 @@ static int hns_roce_v2_post_send(struct ib_qp *ibqp,
 
 		qp->next_sge = sge_idx;
 
-		if (qp->state == IB_QPS_ERR) {
-			attr_mask = IB_QP_STATE;
-			attr.qp_state = IB_QPS_ERR;
-
-			ret = hns_roce_v2_modify_qp(&qp->ibqp, &attr, attr_mask,
-						    qp->state, IB_QPS_ERR);
-			if (ret) {
-				spin_unlock_irqrestore(&qp->sq.lock, flags);
-				*bad_wr = wr;
-				return ret;
-			}
-		}
+		/*
+		 * Hip08 hardware cannot flush the WQEs in SQ if the QP state
+		 * gets into errored mode. Hence, as a workaround to this
+		 * hardware limitation, driver needs to assist in flushing. But
+		 * the flushing operation uses mailbox to convey the QP state to
+		 * the hardware and which can sleep due to the mutex protection
+		 * around the mailbox calls. Hence, use the deferred flush for
+		 * now.
+		 */
+		if (qp->state == IB_QPS_ERR)
+			if (!test_and_set_bit(HNS_ROCE_FLUSH_FLAG,
+					      &qp->flush_flag))
+				init_flush_work(hr_dev, qp);
 	}
 
 	spin_unlock_irqrestore(&qp->sq.lock, flags);
@@ -646,10 +640,8 @@ static int hns_roce_v2_post_recv(struct ib_qp *ibqp,
 	struct hns_roce_v2_wqe_data_seg *dseg;
 	struct hns_roce_rinl_sge *sge_list;
 	struct device *dev = hr_dev->dev;
-	struct ib_qp_attr attr;
 	unsigned long flags;
 	void *wqe = NULL;
-	int attr_mask;
 	u32 wqe_idx;
 	int nreq;
 	int ret;
@@ -719,19 +711,19 @@ static int hns_roce_v2_post_recv(struct ib_qp *ibqp,
 
 		*hr_qp->rdb.db_record = hr_qp->rq.head & 0xffff;
 
-		if (hr_qp->state == IB_QPS_ERR) {
-			attr_mask = IB_QP_STATE;
-			attr.qp_state = IB_QPS_ERR;
-
-			ret = hns_roce_v2_modify_qp(&hr_qp->ibqp, &attr,
-						    attr_mask, hr_qp->state,
-						    IB_QPS_ERR);
-			if (ret) {
-				spin_unlock_irqrestore(&hr_qp->rq.lock, flags);
-				*bad_wr = wr;
-				return ret;
-			}
-		}
+		/*
+		 * Hip08 hardware cannot flush the WQEs in RQ if the QP state
+		 * gets into errored mode. Hence, as a workaround to this
+		 * hardware limitation, driver needs to assist in flushing. But
+		 * the flushing operation uses mailbox to convey the QP state to
+		 * the hardware and which can sleep due to the mutex protection
+		 * around the mailbox calls. Hence, use the deferred flush for
+		 * now.
+		 */
+		if (hr_qp->state == IB_QPS_ERR)
+			if (!test_and_set_bit(HNS_ROCE_FLUSH_FLAG,
+					      &hr_qp->flush_flag))
+				init_flush_work(hr_dev, hr_qp);
 	}
 	spin_unlock_irqrestore(&hr_qp->rq.lock, flags);
 
@@ -3013,13 +3005,11 @@ static int hns_roce_v2_sw_poll_cq(struct hns_roce_cq *hr_cq, int num_entries,
 static int hns_roce_v2_poll_one(struct hns_roce_cq *hr_cq,
 				struct hns_roce_qp **cur_qp, struct ib_wc *wc)
 {
+	struct hns_roce_dev *hr_dev = to_hr_dev(hr_cq->ib_cq.device);
 	struct hns_roce_srq *srq = NULL;
-	struct hns_roce_dev *hr_dev;
 	struct hns_roce_v2_cqe *cqe;
 	struct hns_roce_qp *hr_qp;
 	struct hns_roce_wq *wq;
-	struct ib_qp_attr attr;
-	int attr_mask;
 	int is_send;
 	u16 wqe_ctr;
 	u32 opcode;
@@ -3043,7 +3033,6 @@ static int hns_roce_v2_poll_one(struct hns_roce_cq *hr_cq,
 				V2_CQE_BYTE_16_LCL_QPN_S);
 
 	if (!*cur_qp || (qpn & HNS_ROCE_V2_CQE_QPN_MASK) != (*cur_qp)->qpn) {
-		hr_dev = to_hr_dev(hr_cq->ib_cq.device);
 		hr_qp = __hns_roce_qp_lookup(hr_dev, qpn);
 		if (unlikely(!hr_qp)) {
 			dev_err(hr_dev->dev, "CQ %06lx with entry for unknown QPN %06x\n",
@@ -3053,6 +3042,7 @@ static int hns_roce_v2_poll_one(struct hns_roce_cq *hr_cq,
 		*cur_qp = hr_qp;
 	}
 
+	hr_qp = *cur_qp;
 	wc->qp = &(*cur_qp)->ibqp;
 	wc->vendor_err = 0;
 
@@ -3137,14 +3127,24 @@ static int hns_roce_v2_poll_one(struct hns_roce_cq *hr_cq,
 		break;
 	}
 
-	/* flush cqe if wc status is error, excluding flush error */
-	if ((wc->status != IB_WC_SUCCESS) &&
-	    (wc->status != IB_WC_WR_FLUSH_ERR)) {
-		attr_mask = IB_QP_STATE;
-		attr.qp_state = IB_QPS_ERR;
-		return hns_roce_v2_modify_qp(&(*cur_qp)->ibqp,
-					     &attr, attr_mask,
-					     (*cur_qp)->state, IB_QPS_ERR);
+	/*
+	 * Hip08 hardware cannot flush the WQEs in SQ/RQ if the QP state gets
+	 * into errored mode. Hence, as a workaround to this hardware
+	 * limitation, driver needs to assist in flushing. But the flushing
+	 * operation uses mailbox to convey the QP state to the hardware and
+	 * which can sleep due to the mutex protection around the mailbox calls.
+	 * Hence, use the deferred flush for now. Once wc error detected, the
+	 * flushing operation is needed.
+	 */
+	if (wc->status != IB_WC_SUCCESS &&
+	    wc->status != IB_WC_WR_FLUSH_ERR) {
+		dev_err(hr_dev->dev, "error cqe status is: 0x%x\n",
+			status & HNS_ROCE_V2_CQE_STATUS_MASK);
+
+		if (!test_and_set_bit(HNS_ROCE_FLUSH_FLAG, &hr_qp->flush_flag))
+			init_flush_work(hr_dev, hr_qp);
+
+		return 0;
 	}
 
 	if (wc->status == IB_WC_WR_FLUSH_ERR)
@@ -4735,6 +4735,8 @@ static int hns_roce_v2_modify_qp(struct ib_qp *ibqp,
 	struct hns_roce_v2_qp_context *context = ctx;
 	struct hns_roce_v2_qp_context *qpc_mask = ctx + 1;
 	struct device *dev = hr_dev->dev;
+	unsigned long sq_flag = 0;
+	unsigned long rq_flag = 0;
 	int ret;
 
 	/*
@@ -4752,6 +4754,9 @@ static int hns_roce_v2_modify_qp(struct ib_qp *ibqp,
 
 	/* When QP state is err, SQ and RQ WQE should be flushed */
 	if (new_state == IB_QPS_ERR) {
+		spin_lock_irqsave(&hr_qp->sq.lock, sq_flag);
+		spin_lock_irqsave(&hr_qp->rq.lock, rq_flag);
+		hr_qp->state = IB_QPS_ERR;
 		roce_set_field(context->byte_160_sq_ci_pi,
 			       V2_QPC_BYTE_160_SQ_PRODUCER_IDX_M,
 			       V2_QPC_BYTE_160_SQ_PRODUCER_IDX_S,
@@ -4769,6 +4774,8 @@ static int hns_roce_v2_modify_qp(struct ib_qp *ibqp,
 			       V2_QPC_BYTE_84_RQ_PRODUCER_IDX_M,
 			       V2_QPC_BYTE_84_RQ_PRODUCER_IDX_S, 0);
 		}
+		spin_unlock_irqrestore(&hr_qp->rq.lock, rq_flag);
+		spin_unlock_irqrestore(&hr_qp->sq.lock, sq_flag);
 	}
 
 	/* Configure the optional fields */
diff --git a/drivers/infiniband/hw/hns/hns_roce_qp.c b/drivers/infiniband/hw/hns/hns_roce_qp.c
index dab7314..f885b22 100644
--- a/drivers/infiniband/hw/hns/hns_roce_qp.c
+++ b/drivers/infiniband/hw/hns/hns_roce_qp.c
@@ -57,10 +57,12 @@ static void flush_work_handle(struct work_struct *work)
 	attr_mask = IB_QP_STATE;
 	attr.qp_state = IB_QPS_ERR;
 
-	ret = hns_roce_modify_qp(&hr_qp->ibqp, &attr, attr_mask, NULL);
-	if (ret)
-		dev_err(dev, "Modify QP to error state failed(%d) during CQE flush\n",
-			ret);
+	if (test_and_clear_bit(HNS_ROCE_FLUSH_FLAG, &hr_qp->flush_flag)) {
+		ret = hns_roce_modify_qp(&hr_qp->ibqp, &attr, attr_mask, NULL);
+		if (ret)
+			dev_err(dev, "Modify QP to error state failed(%d) during CQE flush\n",
+				ret);
+	}
 
 	/*
 	 * make sure we signal QP destroy leg that flush QP was completed
@@ -761,6 +763,7 @@ static int hns_roce_create_qp_common(struct hns_roce_dev *hr_dev,
 	spin_lock_init(&hr_qp->rq.lock);
 
 	hr_qp->state = IB_QPS_RESET;
+	hr_qp->flush_flag = 0;
 
 	hr_qp->ibqp.qp_type = init_attr->qp_type;
 
-- 
2.7.4

Re: [PATCH v8 for-next 0/2] Add the workqueue framework for flush cqe handler

[Jason Gunthorpe]

On Thu, Feb 06, 2020 at 05:56:43PM +0800, Yixian Liu wrote:
> Earlier Background:
> HiP08 RoCE hardware lacks ability(a known hardware problem) to flush
> outstanding WQEs if QP state gets into errored mode for some reason.
> To overcome this hardware problem and as a workaround, when QP is
> detected to be in errored state during various legs like post send,
> post receive etc [1], flush needs to be performed from the driver.
> 
> These data-path legs might get called concurrently from various context,
> like thread and interrupt as well (like NVMe driver). Hence, these need
> to be protected with spin-locks for the concurrency. This code exists
> within the driver.
> 
> Problem:
> Earlier The patch[1] sent to solve the hardware limitation explained
> in the background section had a bug in the software flushing leg. It
> acquired mutex while modifying QP state to errored state and while
> conveying it to the hardware using the mailbox. This caused leg to
> sleep while holding spin-lock and caused crash.
> 
> Suggested Solution:
> In this patch, we have proposed to defer the flushing of the QP in
> Errored state using the workqueue.
> 
> We do understand that this might have an impact on the recovery times
> as scheduling of the workqueue handler depends upon the occupancy of
> the system. Therefore to roughly mitigate this affect we have tried
> to use Concurrency Managed workqueue to give worker thread (and
> hence handler) a chance to run over more than one core.
> 
> 
> [1] https://patchwork.kernel.org/patch/10534271/
> 
> 
> This patch-set consists of:
> [Patch 001] Introduce workqueue based WQE Flush Handler
> [Patch 002] Call WQE flush handler in post {send|receive|poll}

Applied to for-next

Thanks,
Jason