[PATCH v4 15/17] bnxt_en: 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>,
	Michael Chan <michael.chan@broadcom.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v4 15/17] bnxt_en: Eliminate duplicate barriers on weakly-ordered archs
Date: Mon, 19 Mar 2018 22:42:30 -0400	[thread overview]
Message-ID: <1521513753-7325-16-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().

Since code already has an explicit barrier call, changing writel() to
writel_relaxed().

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c         |  2 +-
 drivers/net/ethernet/broadcom/bnxt/bnxt.h         | 11 ++++++++++-
 drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c |  2 +-
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 1500243..befb538 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -1922,7 +1922,7 @@ static int bnxt_poll_work(struct bnxt *bp, struct bnxt_napi *bnapi, int budget)
 		/* Sync BD data before updating doorbell */
 		wmb();
 
-		bnxt_db_write(bp, db, DB_KEY_TX | prod);
+		bnxt_db_write_relaxed(bp, db, DB_KEY_TX | prod);
 	}
 
 	cpr->cp_raw_cons = raw_cons;
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index 1989c47..4c0d048 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -1402,11 +1402,20 @@ static inline u32 bnxt_tx_avail(struct bnxt *bp, struct bnxt_tx_ring_info *txr)
 }
 
 /* For TX and RX ring doorbells */
+static inline void bnxt_db_write_relaxed(struct bnxt *bp, void __iomem *db,
+					 u32 val)
+{
+	writel_relaxed(val, db);
+	if (bp->flags & BNXT_FLAG_DOUBLE_DB)
+		writel_relaxed(val, db);
+}
+
+/* For TX and RX ring doorbells */
 static inline void bnxt_db_write(struct bnxt *bp, void __iomem *db, u32 val)
 {
 	writel(val, db);
 	if (bp->flags & BNXT_FLAG_DOUBLE_DB)
-		writel(val, db);
+		writel_relaxed(val, db);
 }
 
 extern const u16 bnxt_lhint_arr[];
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
index 1801582..a1b1060 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -2403,7 +2403,7 @@ static int bnxt_run_loopback(struct bnxt *bp)
 	/* Sync BD data before updating doorbell */
 	wmb();
 
-	bnxt_db_write(bp, txr->tx_doorbell, DB_KEY_TX | txr->tx_prod);
+	bnxt_db_write_relaxed(bp, txr->tx_doorbell, DB_KEY_TX | txr->tx_prod);
 	rc = bnxt_poll_loopback(bp, pkt_size);
 
 	dma_unmap_single(&bp->pdev->dev, map, pkt_size, PCI_DMA_TODEVICE);
-- 
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 15/17] bnxt_en: Eliminate duplicate barriers on weakly-ordered archs
Date: Mon, 19 Mar 2018 22:42:30 -0400	[thread overview]
Message-ID: <1521513753-7325-16-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().

Since code already has an explicit barrier call, changing writel() to
writel_relaxed().

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/net/ethernet/broadcom/bnxt/bnxt.c         |  2 +-
 drivers/net/ethernet/broadcom/bnxt/bnxt.h         | 11 ++++++++++-
 drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c |  2 +-
 3 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.c b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
index 1500243..befb538 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -1922,7 +1922,7 @@ static int bnxt_poll_work(struct bnxt *bp, struct bnxt_napi *bnapi, int budget)
 		/* Sync BD data before updating doorbell */
 		wmb();
 
-		bnxt_db_write(bp, db, DB_KEY_TX | prod);
+		bnxt_db_write_relaxed(bp, db, DB_KEY_TX | prod);
 	}
 
 	cpr->cp_raw_cons = raw_cons;
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt.h b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
index 1989c47..4c0d048 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -1402,11 +1402,20 @@ static inline u32 bnxt_tx_avail(struct bnxt *bp, struct bnxt_tx_ring_info *txr)
 }
 
 /* For TX and RX ring doorbells */
+static inline void bnxt_db_write_relaxed(struct bnxt *bp, void __iomem *db,
+					 u32 val)
+{
+	writel_relaxed(val, db);
+	if (bp->flags & BNXT_FLAG_DOUBLE_DB)
+		writel_relaxed(val, db);
+}
+
+/* For TX and RX ring doorbells */
 static inline void bnxt_db_write(struct bnxt *bp, void __iomem *db, u32 val)
 {
 	writel(val, db);
 	if (bp->flags & BNXT_FLAG_DOUBLE_DB)
-		writel(val, db);
+		writel_relaxed(val, db);
 }
 
 extern const u16 bnxt_lhint_arr[];
diff --git a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
index 1801582..a1b1060 100644
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt_ethtool.c
@@ -2403,7 +2403,7 @@ static int bnxt_run_loopback(struct bnxt *bp)
 	/* Sync BD data before updating doorbell */
 	wmb();
 
-	bnxt_db_write(bp, txr->tx_doorbell, DB_KEY_TX | txr->tx_prod);
+	bnxt_db_write_relaxed(bp, txr->tx_doorbell, DB_KEY_TX | txr->tx_prod);
 	rc = bnxt_poll_loopback(bp, pkt_size);
 
 	dma_unmap_single(&bp->pdev->dev, map, pkt_size, PCI_DMA_TODEVICE);
-- 
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 ` [PATCH v4 13/17] net: cxgb3: " Sinan Kaya
2018-03-20  2:42   ` 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 ` Sinan Kaya [this message]
2018-03-20  2:42   ` [PATCH v4 15/17] bnxt_en: " 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:1500243 dfblob:befb538 dfblob:1989c47 dfblob:4c0d048
dfblob:1801582 dfblob:a1b1060 dfblob:1500243 dfblob:befb538
dfblob:1989c47 dfblob:4c0d048 dfblob:1801582 dfblob:a1b1060 )
 OR (
bs:"[PATCH v4 15/17] bnxt_en: Eliminate duplicate barriers on weakly-ordered archs" )
	(help)

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