[ 087/108] SCSI: scsi_lib: fix scsi_io_completions SG_IO error propagation

From: Greg Kroah-Hartman
Date: Wed Sep 12 2012 - 19:35:59 EST


From: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>

3.5-stable review patch. If anyone has any objections, please let me know.

------------------

From: Mike Snitzer <snitzer@xxxxxxxxxx>

commit 27c419739b67decced4650440829b8d51bef954b upstream.

The following v3.4-rc1 commit unmasked an existing bug in scsi_io_completion's
SG_IO error handling: 47ac56d [SCSI] scsi_error: classify some ILLEGAL_REQUEST
sense as a permanent TARGET_ERROR

Given that certain ILLEGAL_REQUEST are now properly categorized as
TARGET_ERROR the host_byte is being set (before host_byte wasn't ever
set for these ILLEGAL_REQUEST).

In scsi_io_completion, initialize req->errors with cmd->result _after_
the SG_IO block that calls __scsi_error_from_host_byte (which may
modify the host_byte).

Before this fix:

cdb to send: 12 01 01 00 00 00
ioctl(3, SG_IO, {'S', SG_DXFER_NONE, cmd[6]=[12, 01, 01, 00, 00, 00],
mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=20000, flags=0,
status=02, masked_status=01, sb[19]=[70, 00, 05, 00, 00, 00, 00, 0b,
00, 00, 00, 00, 24, 00, 00, 00, 00, 00, 00], host_status=0x10,
driver_status=0x8, resid=0, duration=0, info=0x1}) = 0
SCSI Status: Check Condition

Sense Information:
sense buffer empty

After:

cdb to send: 12 01 01 00 00 00
ioctl(3, SG_IO, {'S', SG_DXFER_NONE, cmd[6]=[12, 01, 01, 00, 00, 00],
mx_sb_len=32, iovec_count=0, dxfer_len=0, timeout=20000, flags=0,
status=02, masked_status=01, sb[19]=[70, 00, 05, 00, 00, 00, 00, 0b,
00, 00, 00, 00, 24, 00, 00, 00, 00, 00, 00], host_status=0,
driver_status=0x8, resid=0, duration=0, info=0x1}) = 0
SCSI Status: Check Condition

Sense Information:
Fixed format, current; Sense key: Illegal Request
Additional sense: Invalid field in cdb
Raw sense data (in hex):
70 00 05 00 00 00 00 0b 00 00 00 00 24 00 00 00
00 00 00

Reported-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Tested-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Reviewed-by: Babu Moger <babu.moger@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: James Bottomley <JBottomley@xxxxxxxxxxxxx>

---
drivers/scsi/scsi_lib.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -760,7 +760,6 @@ void scsi_io_completion(struct scsi_cmnd
}

if (req->cmd_type == REQ_TYPE_BLOCK_PC) { /* SG_IO ioctl from block level */
- req->errors = result;
if (result) {
if (sense_valid && req->sense) {
/*
@@ -776,6 +775,10 @@ void scsi_io_completion(struct scsi_cmnd
if (!sense_deferred)
error = __scsi_error_from_host_byte(cmd, result);
}
+ /*
+ * __scsi_error_from_host_byte may have reset the host_byte
+ */
+ req->errors = cmd->result;

req->resid_len = scsi_get_resid(cmd);



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