From f2233a33dc1fef4aa30dc11e4c676637bf358c3d Mon Sep 17 00:00:00 2001
From: Arnd Bergmann <arnd@arndb.de>
Date: Mon, 19 Mar 2018 22:50:05 -0400
Subject: [PATCH] scsi: ipr: Eliminate duplicate barriers
References: FATE#326436
Patch-mainline: v4.18-rc3
Git-commit: f2233a33dc1fef4aa30dc11e4c676637bf358c3d
Driver does both wmb() and writel(). The latter already has a barrier
on some architectures like arm64. This ends up with CPU observing two
barriers back to back before executing the register write.
Drivers should generally assume that the barrier implied by writel() is
sufficient for ordering DMA. Remove the extraneous wmb() before it.
[mkp: Squashed Arnd's and Sinan's patches]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Sinan Kaya <okaya@codeaurora.org>
Acked-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
drivers/scsi/ipr.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index 0a9b8b387bd2..02d65dce74e5 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -760,7 +760,6 @@ static void ipr_mask_and_clear_interrupts(struct ipr_ioa_cfg *ioa_cfg,
ioa_cfg->hrrq[i].allow_interrupts = 0;
spin_unlock(&ioa_cfg->hrrq[i]._lock);
}
- wmb();
/* Set interrupt mask to stop all new interrupts */
if (ioa_cfg->sis64)
@@ -8403,7 +8402,6 @@ static int ipr_reset_enable_ioa(struct ipr_cmnd *ipr_cmd)
ioa_cfg->hrrq[i].allow_interrupts = 1;
spin_unlock(&ioa_cfg->hrrq[i]._lock);
}
- wmb();
if (ioa_cfg->sis64) {
/* Set the adapter to the correct endian mode. */
writel(IPR_ENDIAN_SWAP_KEY, ioa_cfg->regs.endian_swap_reg);
--
2.13.7