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From: Sinan Kaya <okaya@codeaurora.org>
To: linux-scsi@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>,
	Don Brace <don.brace@microsemi.com>,
	"James E.J. Bottomley" <jejb@linux.vnet.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	esc.storagedev@microsemi.com, linux-kernel@vger.kernel.org
Subject: [PATCH v4 1/7] scsi: hpsa: Eliminate duplicate barriers on weakly-ordered archs
Date: Mon, 19 Mar 2018 22:50:01 -0400	[thread overview]
Message-ID: <1521514207-10695-2-git-send-email-okaya@codeaurora.org> (raw)
In-Reply-To: <1521514207-10695-1-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.

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

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/scsi/hpsa.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
index 018f980..c7d7e6a 100644
--- a/drivers/scsi/hpsa.h
+++ b/drivers/scsi/hpsa.h
@@ -599,7 +599,7 @@ static unsigned long SA5_ioaccel_mode1_completed(struct ctlr_info *h, u8 q)
 		 * but with current driver design this is easiest.
 		 */
 		wmb();
-		writel((q << 24) | rq->current_entry, h->vaddr +
+		writel_relaxed((q << 24) | rq->current_entry, h->vaddr +
 				IOACCEL_MODE1_CONSUMER_INDEX);
 		atomic_dec(&h->commands_outstanding);
 	}
-- 
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 1/7] scsi: hpsa: Eliminate duplicate barriers on weakly-ordered archs
Date: Mon, 19 Mar 2018 22:50:01 -0400	[thread overview]
Message-ID: <1521514207-10695-2-git-send-email-okaya@codeaurora.org> (raw)
In-Reply-To: <1521514207-10695-1-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.

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

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
---
 drivers/scsi/hpsa.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/hpsa.h b/drivers/scsi/hpsa.h
index 018f980..c7d7e6a 100644
--- a/drivers/scsi/hpsa.h
+++ b/drivers/scsi/hpsa.h
@@ -599,7 +599,7 @@ static unsigned long SA5_ioaccel_mode1_completed(struct ctlr_info *h, u8 q)
 		 * but with current driver design this is easiest.
 		 */
 		wmb();
-		writel((q << 24) | rq->current_entry, h->vaddr +
+		writel_relaxed((q << 24) | rq->current_entry, h->vaddr +
 				IOACCEL_MODE1_CONSUMER_INDEX);
 		atomic_dec(&h->commands_outstanding);
 	}
-- 
2.7.4

  reply	other threads:[~2018-03-20  2:50 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-20  2:50 [PATCH v4 0/7] scsi: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-20  2:50 ` Sinan Kaya
2018-03-20  2:50 ` Sinan Kaya [this message]
2018-03-20  2:50   ` [PATCH v4 1/7] scsi: hpsa: " Sinan Kaya
2018-03-20 14:01   ` Don Brace
2018-03-20 14:01     ` Don Brace
2018-03-20 16:51   ` Laurence Oberman
2018-03-20 16:51     ` Laurence Oberman
2018-03-20  2:50 ` [PATCH v4 2/7] scsi: megaraid: eliminate " Sinan Kaya
2018-03-20  2:50   ` Sinan Kaya
2018-03-20  2:50 ` [PATCH v4 3/7] scsi: dpt_i2o: " Sinan Kaya
2018-03-20  2:50   ` Sinan Kaya
2018-03-20 10:23   ` Christoph Hellwig
2018-03-20 10:23     ` Christoph Hellwig
2018-03-20 12:13     ` okaya
2018-03-20 12:13       ` okaya at codeaurora.org
2018-03-20  2:50 ` [PATCH v4 4/7] scsi: lpfc: Eliminate " Sinan Kaya
2018-03-20  2:50   ` Sinan Kaya
2018-03-20  2:50 ` [PATCH v4 5/7] scsi: ipr: " Sinan Kaya
2018-03-20  2:50   ` Sinan Kaya
2018-05-29 20:45   ` Brian King
2018-05-29 20:45     ` Brian King
2018-03-20  2:50 ` [PATCH v4 6/7] scsi: bnx2i: " Sinan Kaya
2018-03-20  2:50   ` Sinan Kaya
2018-03-20  2:50 ` [PATCH v4 7/7] scsi: csiostor: " Sinan Kaya
2018-03-20  2:50   ` Sinan Kaya

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