linux-kernel - [PATCH 7/7] scsi: mac_scsi: Treat Last Byte Sent time-out as failure

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Date:   Sun, 02 Jun 2019 11:24:12 +1000
From:   Finn Thain <fthain@...egraphics.com.au>
To:     "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>
Cc:     "Michael Schmitz" <schmitzmic@...il.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 7/7] scsi: mac_scsi: Treat Last Byte Sent time-out as failure

A system bus error during a PDMA send operation can result in bytes being
lost. Theoretically that could cause the target to remain in DATA OUT
phase and the initiator (expecting a phase change) would time-out waiting
for the Last Byte Sent flag. Should that happen, fail the transfer so the
core driver will stop using PDMA with this target.

Cc: Michael Schmitz <schmitzmic@...il.com>
Tested-by: Stan Johnson <userm57@...oo.com>
Signed-off-by: Finn Thain <fthain@...egraphics.com.au>
---
 drivers/scsi/mac_scsi.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/mac_scsi.c b/drivers/scsi/mac_scsi.c
index 2e503f06ac99..68d4665112b5 100644
--- a/drivers/scsi/mac_scsi.c
+++ b/drivers/scsi/mac_scsi.c
@@ -188,9 +188,12 @@ static inline int macscsi_pwrite(struct NCR5380_hostdata *hostdata,
 		if (hostdata->pdma_residual == 0) {
 			if (NCR5380_poll_politely(hostdata, TARGET_COMMAND_REG,
 			                          TCR_LAST_BYTE_SENT,
-			                          TCR_LAST_BYTE_SENT, HZ / 64) < 0)
+			                          TCR_LAST_BYTE_SENT,
+			                          HZ / 64) < 0) {
 				scmd_printk(KERN_ERR, hostdata->connected,
 				            "%s: Last Byte Sent timeout\n", __func__);
+				result = -1;
+			}
 			goto out;
 		}
 
-- 
2.21.0