linux-kernel - [PATCH 5.12 029/173] scsi: vmw_pvscsi: Set correct residual data length

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Date:   Mon, 14 Jun 2021 12:26:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Matt Wang <wwentao@...are.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.12 029/173] scsi: vmw_pvscsi: Set correct residual data length

From: Matt Wang <wwentao@...are.com>

[ Upstream commit e662502b3a782d479e67736a5a1c169a703d853a ]

Some commands (such as INQUIRY) may return less data than the initiator
requested. To avoid conducting useless information, set the right residual
count to make upper layer aware of this.

Before (INQUIRY PAGE 0xB0 with 128B buffer):

$ sg_raw -r 128 /dev/sda 12 01 B0 00 80 00
SCSI Status: Good

Received 128 bytes of data:
 00 00 b0 00 3c 01 00 00 00 00 00 00 00 00 00 00 00 ...<............
 10 00 00 00 00 00 01 00 00 00 00 00 40 00 00 08 00 ...........@....
 20 80 00 00 00 00 00 00 00 00 00 20 00 00 00 00 00 .......... .....
 30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
 40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
 50 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
 60 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
 70 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

After:

$ sg_raw -r 128 /dev/sda 12 01 B0 00 80 00
SCSI Status: Good

Received 64 bytes of data:
00 00 b0 00 3c 01 00 00 00 00 00 00 00 00 00 00 00 ...<............
10 00 00 00 00 00 01 00 00 00 00 00 40 00 00 08 00 ...........@....
20 80 00 00 00 00 00 00 00 00 00 20 00 00 00 00 00 .......... .....
30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................

[mkp: clarified description]

Link: https://lore.kernel.org/r/03C41093-B62E-43A2-913E-CFC92F1C70C3@vmware.com
Signed-off-by: Matt Wang <wwentao@...are.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/scsi/vmw_pvscsi.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/vmw_pvscsi.c b/drivers/scsi/vmw_pvscsi.c
index 8a79605d9652..b9969fce6b4d 100644
--- a/drivers/scsi/vmw_pvscsi.c
+++ b/drivers/scsi/vmw_pvscsi.c
@@ -585,7 +585,13 @@ static void pvscsi_complete_request(struct pvscsi_adapter *adapter,
 		case BTSTAT_SUCCESS:
 		case BTSTAT_LINKED_COMMAND_COMPLETED:
 		case BTSTAT_LINKED_COMMAND_COMPLETED_WITH_FLAG:
-			/* If everything went fine, let's move on..  */
+			/*
+			 * Commands like INQUIRY may transfer less data than
+			 * requested by the initiator via bufflen. Set residual
+			 * count to make upper layer aware of the actual amount
+			 * of data returned.
+			 */
+			scsi_set_resid(cmd, scsi_bufflen(cmd) - e->dataLen);
 			cmd->result = (DID_OK << 16);
 			break;
 
-- 
2.30.2