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[v6,1/6] net: qla3xxx: Eliminate duplicate barriers on weakly-ordered archs

Message ID 1521843791-21201-2-git-send-email-okaya@codeaurora.org
State Superseded, archived
Delegated to: David Miller
Headers show
Series netdev: Eliminate duplicate barriers on weakly-ordered archs | expand

Commit Message

Sinan Kaya March 23, 2018, 10:23 p.m. UTC 
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.

Since code already has an explicit barrier call, changing code to

wmb()
writel_relaxed()
mmiowb()

for multi-arch support.

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/net/ethernet/qlogic/qla3xxx.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
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Patch

diff --git a/drivers/net/ethernet/qlogic/qla3xxx.c b/drivers/net/ethernet/qlogic/qla3xxx.c
index 9e5264d..b48f761 100644
--- a/drivers/net/ethernet/qlogic/qla3xxx.c
+++ b/drivers/net/ethernet/qlogic/qla3xxx.c
@@ -1858,8 +1858,9 @@  static void ql_update_small_bufq_prod_index(struct ql3_adapter *qdev)
 			qdev->small_buf_release_cnt -= 8;
 		}
 		wmb();
-		writel(qdev->small_buf_q_producer_index,
-			&port_regs->CommonRegs.rxSmallQProducerIndex);
+		writel_relaxed(qdev->small_buf_q_producer_index,
+			       &port_regs->CommonRegs.rxSmallQProducerIndex);
+		mmiowb();
 	}
 }