[PATCH v4 13/17] net: cxgb3: Eliminate duplicate barriers on weakly-ordered archs

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From: Sinan Kaya <okaya@codeaurora.org>
To: netdev@vger.kernel.org, timur@codeaurora.org, sulrich@codeaurora.org
Cc: linux-arm-msm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Sinan Kaya <okaya@codeaurora.org>,
	Santosh Raspatur <santosh@chelsio.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v4 13/17] net: cxgb3: Eliminate duplicate barriers on weakly-ordered archs
Date: Mon, 19 Mar 2018 22:42:28 -0400	[thread overview]
Message-ID: <1521513753-7325-14-git-send-email-okaya@codeaurora.org> (raw)
In-Reply-To: <1521513753-7325-1-git-send-email-okaya@codeaurora.org>

Code includes wmb() followed by writel(). writel() already has a barrier on
some architectures like arm64.

This ends up CPU observing two barriers back to back before executing the
register write.

Create a new wrapper function with relaxed write operator. Use the new
wrapper when a write is following a wmb().

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/net/ethernet/chelsio/cxgb3/adapter.h |  7 +++++++
 drivers/net/ethernet/chelsio/cxgb3/sge.c     | 19 ++++++++++---------
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb3/adapter.h b/drivers/net/ethernet/chelsio/cxgb3/adapter.h
index 087ff0f..0e21e66 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/adapter.h
+++ b/drivers/net/ethernet/chelsio/cxgb3/adapter.h
@@ -281,6 +281,13 @@ static inline void t3_write_reg(struct adapter *adapter, u32 reg_addr, u32 val)
 	writel(val, adapter->regs + reg_addr);
 }
 
+static inline void t3_write_reg_relaxed(struct adapter *adapter, u32 reg_addr,
+					u32 val)
+{
+	CH_DBG(adapter, MMIO, "setting register 0x%x to 0x%x\n", reg_addr, val);
+	writel_relaxed(val, adapter->regs + reg_addr);
+}
+
 static inline struct port_info *adap2pinfo(struct adapter *adap, int idx)
 {
 	return netdev_priv(adap->port[idx]);
diff --git a/drivers/net/ethernet/chelsio/cxgb3/sge.c b/drivers/net/ethernet/chelsio/cxgb3/sge.c
index e988caa..0baab06 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb3/sge.c
@@ -487,7 +487,8 @@ static inline void ring_fl_db(struct adapter *adap, struct sge_fl *q)
 	if (q->pend_cred >= q->credits / 4) {
 		q->pend_cred = 0;
 		wmb();
-		t3_write_reg(adap, A_SG_KDOORBELL, V_EGRCNTX(q->cntxt_id));
+		t3_write_reg_relaxed(adap, A_SG_KDOORBELL,
+				     V_EGRCNTX(q->cntxt_id));
 	}
 }
 
@@ -1058,8 +1059,8 @@ static inline void check_ring_tx_db(struct adapter *adap, struct sge_txq *q)
 	}
 #else
 	wmb();			/* write descriptors before telling HW */
-	t3_write_reg(adap, A_SG_KDOORBELL,
-		     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
+	t3_write_reg_relaxed(adap, A_SG_KDOORBELL,
+			     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
 #endif
 }
 
@@ -1510,8 +1511,8 @@ static int ctrl_xmit(struct adapter *adap, struct sge_txq *q,
 	}
 	spin_unlock(&q->lock);
 	wmb();
-	t3_write_reg(adap, A_SG_KDOORBELL,
-		     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
+	t3_write_reg_relaxed(adap, A_SG_KDOORBELL,
+			     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
 	return NET_XMIT_SUCCESS;
 }
 
@@ -1554,8 +1555,8 @@ static void restart_ctrlq(unsigned long data)
 
 	spin_unlock(&q->lock);
 	wmb();
-	t3_write_reg(qs->adap, A_SG_KDOORBELL,
-		     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
+	t3_write_reg_relaxed(qs->adap, A_SG_KDOORBELL,
+			     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
 }
 
 /*
@@ -1793,8 +1794,8 @@ again:	reclaim_completed_tx(adap, q, TX_RECLAIM_CHUNK);
 #endif
 	wmb();
 	if (likely(written))
-		t3_write_reg(adap, A_SG_KDOORBELL,
-			     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
+		t3_write_reg_relaxed(adap, A_SG_KDOORBELL,
+				     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
 }
 
 /**
-- 
2.7.4

WARNING: multiple messages have this Message-ID (diff)

From: okaya@codeaurora.org (Sinan Kaya)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v4 13/17] net: cxgb3: Eliminate duplicate barriers on weakly-ordered archs
Date: Mon, 19 Mar 2018 22:42:28 -0400	[thread overview]
Message-ID: <1521513753-7325-14-git-send-email-okaya@codeaurora.org> (raw)
In-Reply-To: <1521513753-7325-1-git-send-email-okaya@codeaurora.org>

Code includes wmb() followed by writel(). writel() already has a barrier on
some architectures like arm64.

This ends up CPU observing two barriers back to back before executing the
register write.

Create a new wrapper function with relaxed write operator. Use the new
wrapper when a write is following a wmb().

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/net/ethernet/chelsio/cxgb3/adapter.h |  7 +++++++
 drivers/net/ethernet/chelsio/cxgb3/sge.c     | 19 ++++++++++---------
 2 files changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/net/ethernet/chelsio/cxgb3/adapter.h b/drivers/net/ethernet/chelsio/cxgb3/adapter.h
index 087ff0f..0e21e66 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/adapter.h
+++ b/drivers/net/ethernet/chelsio/cxgb3/adapter.h
@@ -281,6 +281,13 @@ static inline void t3_write_reg(struct adapter *adapter, u32 reg_addr, u32 val)
 	writel(val, adapter->regs + reg_addr);
 }
 
+static inline void t3_write_reg_relaxed(struct adapter *adapter, u32 reg_addr,
+					u32 val)
+{
+	CH_DBG(adapter, MMIO, "setting register 0x%x to 0x%x\n", reg_addr, val);
+	writel_relaxed(val, adapter->regs + reg_addr);
+}
+
 static inline struct port_info *adap2pinfo(struct adapter *adap, int idx)
 {
 	return netdev_priv(adap->port[idx]);
diff --git a/drivers/net/ethernet/chelsio/cxgb3/sge.c b/drivers/net/ethernet/chelsio/cxgb3/sge.c
index e988caa..0baab06 100644
--- a/drivers/net/ethernet/chelsio/cxgb3/sge.c
+++ b/drivers/net/ethernet/chelsio/cxgb3/sge.c
@@ -487,7 +487,8 @@ static inline void ring_fl_db(struct adapter *adap, struct sge_fl *q)
 	if (q->pend_cred >= q->credits / 4) {
 		q->pend_cred = 0;
 		wmb();
-		t3_write_reg(adap, A_SG_KDOORBELL, V_EGRCNTX(q->cntxt_id));
+		t3_write_reg_relaxed(adap, A_SG_KDOORBELL,
+				     V_EGRCNTX(q->cntxt_id));
 	}
 }
 
@@ -1058,8 +1059,8 @@ static inline void check_ring_tx_db(struct adapter *adap, struct sge_txq *q)
 	}
 #else
 	wmb();			/* write descriptors before telling HW */
-	t3_write_reg(adap, A_SG_KDOORBELL,
-		     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
+	t3_write_reg_relaxed(adap, A_SG_KDOORBELL,
+			     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
 #endif
 }
 
@@ -1510,8 +1511,8 @@ static int ctrl_xmit(struct adapter *adap, struct sge_txq *q,
 	}
 	spin_unlock(&q->lock);
 	wmb();
-	t3_write_reg(adap, A_SG_KDOORBELL,
-		     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
+	t3_write_reg_relaxed(adap, A_SG_KDOORBELL,
+			     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
 	return NET_XMIT_SUCCESS;
 }
 
@@ -1554,8 +1555,8 @@ static void restart_ctrlq(unsigned long data)
 
 	spin_unlock(&q->lock);
 	wmb();
-	t3_write_reg(qs->adap, A_SG_KDOORBELL,
-		     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
+	t3_write_reg_relaxed(qs->adap, A_SG_KDOORBELL,
+			     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
 }
 
 /*
@@ -1793,8 +1794,8 @@ again:	reclaim_completed_tx(adap, q, TX_RECLAIM_CHUNK);
 #endif
 	wmb();
 	if (likely(written))
-		t3_write_reg(adap, A_SG_KDOORBELL,
-			     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
+		t3_write_reg_relaxed(adap, A_SG_KDOORBELL,
+				     F_SELEGRCNTX | V_EGRCNTX(q->cntxt_id));
 }
 
 /**
-- 
2.7.4

next prev parent reply	other threads:[~2018-03-20  2:42 UTC|newest]

Thread overview: 57+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-20  2:42 [PATCH v4 00/17] netdev: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-20  2:42 ` Sinan Kaya
2018-03-20  2:42 ` [Intel-wired-lan] [PATCH v4 01/17] i40e/i40evf: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [Intel-wired-lan] [PATCH v4 02/17] ixgbe: eliminate " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [Intel-wired-lan] [PATCH v4 03/17] igbvf: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [Intel-wired-lan] [PATCH v4 04/17] igb: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [Intel-wired-lan] [PATCH v4 05/17] ixgbevf: keep writel() closer to wmb() Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [Intel-wired-lan] [PATCH v4 06/17] ixgbevf: eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [Intel-wired-lan] [PATCH v4 07/17] fm10k: Eliminate " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [PATCH v4 08/17] drivers: net: cxgb: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [PATCH v4 09/17] net: qla3xxx: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [PATCH v4 10/17] qlcnic: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [PATCH v4 11/17] bnx2x: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-22 10:10   ` Kalluru, Sudarsana
2018-03-22 10:10     ` Kalluru, Sudarsana
2018-03-20  2:42 ` [PATCH v4 12/17] net: cxgb4/cxgb4vf: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-21 23:03   ` Casey Leedom
2018-03-21 23:03     ` Casey Leedom
2018-03-22  0:00     ` okaya
2018-03-22  0:00       ` okaya at codeaurora.org
2018-03-20  2:42 ` Sinan Kaya [this message]
2018-03-20  2:42   ` [PATCH v4 13/17] net: cxgb3: " Sinan Kaya
2018-03-20  2:42 ` [PATCH v4 14/17] net: qlge: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [PATCH v4 15/17] bnxt_en: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [PATCH v4 16/17] qed/qede: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-20  2:42 ` [PATCH v4 17/17] net: ena: " Sinan Kaya
2018-03-20  2:42   ` Sinan Kaya
2018-03-25 12:06   ` Belgazal, Netanel
2018-03-25 12:06     ` Belgazal, Netanel
2018-03-25 13:33     ` okaya
2018-03-25 13:33       ` okaya at codeaurora.org
2018-03-21 15:56 ` [PATCH v4 00/17] netdev: " David Miller
2018-03-21 15:56   ` David Miller
2018-03-21 19:06   ` Sinan Kaya
2018-03-21 19:06     ` Sinan Kaya

find likely ancestor, descendant, or conflicting patches for this message:
( dfblob:087ff0f dfblob:0e21e66 dfblob:e988caa dfblob:0baab06
dfblob:087ff0f dfblob:0e21e66 dfblob:e988caa dfblob:0baab06 )
 OR (
bs:"[PATCH v4 13/17] net: cxgb3: Eliminate duplicate barriers on weakly-ordered archs" )
	(help)

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