netdev - [PATCH net-next 27/31] iw_cxgb4: wc_wmb() needed after DB writes.

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Message-Id: <1393427230-14532-28-git-send-email-hariprasad@chelsio.com>
Date:	Wed, 26 Feb 2014 20:37:06 +0530
From:	Hariprasad Shenai <hariprasad@...lsio.com>
To:	netdev@...r.kernel.org, linux-rdma@...r.kernel.org
Cc:	davem@...emloft.net, roland@...estorage.com, kumaras@...lsio.com,
	dm@...lsio.com, swise@...ngridcomputing.com, leedom@...lsio.com,
	santosh@...lsio.com, hariprasad@...lsio.com, nirranjan@...lsio.com
Subject: [PATCH net-next 27/31] iw_cxgb4: wc_wmb() needed after DB writes.

From: Steve Wise <swise@...ngridcomputing.com>

Need to do an sfence after both the WC and regular PIDX DB write.
Otherwise the host might reorder things and cause work request corruption
(seen with NFSRDMA).

Signed-off-by: Steve Wise <swise@...ngridcomputing.com>
---
 drivers/infiniband/hw/cxgb4/t4.h |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/cxgb4/t4.h b/drivers/infiniband/hw/cxgb4/t4.h
index 67cd09e..ace3154 100644
--- a/drivers/infiniband/hw/cxgb4/t4.h
+++ b/drivers/infiniband/hw/cxgb4/t4.h
@@ -470,12 +470,12 @@ static inline void t4_ring_sq_db(struct t4_wq *wq, u16 inc, u8 t5,
 			PDBG("%s: WC wq->sq.pidx = %d\n",
 			     __func__, wq->sq.pidx);
 			pio_copy(wq->sq.udb + 7, (void *)wqe);
-			wc_wmb();
 		} else {
 			PDBG("%s: DB wq->sq.pidx = %d\n",
 			     __func__, wq->sq.pidx);
 			writel(PIDX_T5(inc), wq->sq.udb);
 		}
+		wc_wmb();
 		return;
 	}
 	writel(QID(wq->sq.qid) | PIDX(inc), wq->db);
@@ -490,12 +490,12 @@ static inline void t4_ring_rq_db(struct t4_wq *wq, u16 inc, u8 t5,
 			PDBG("%s: WC wq->rq.pidx = %d\n",
 			     __func__, wq->rq.pidx);
 			pio_copy(wq->rq.udb + 7, (void *)wqe);
-			wc_wmb();
 		} else {
 			PDBG("%s: DB wq->rq.pidx = %d\n",
 			     __func__, wq->rq.pidx);
 			writel(PIDX_T5(inc), wq->rq.udb);
 		}
+		wc_wmb();
 		return;
 	}
 	writel(QID(wq->rq.qid) | PIDX(inc), wq->db);
-- 
1.7.1

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