On Wed, 4 Apr 2018 10:53:55 -0700 "Bart Van Assche" bart.vanassche@wdc.com wrote:
Commit e39a97353e53 modified __scsi_error_from_host_byte() such that that function translates DID_OK into BLK_STS_OK. However, the description of that commit is wrong: it mentions that commit 2a842acab109 introduced a bug in __scsi_error_from_host_byte() although that commit did not change the behavior of that function. Additionally, commit e39a97353e53 introduced a severe bug: it causes commands that fail with hostbyte=DID_OK and driverbyte=DRIVER_SENSE to be completed with BLK_STS_OK. Fix __scsi_error_from_host_byte() by only translating good status values into BLK_STS_OK.
Fixes: e39a97353e53 ("scsi: core: return BLK_STS_OK for DID_OK in __scsi_error_from_host_byte()") Reported-by: Damien Le Moal damien.lemoal@wdc.com Signed-off-by: Bart Van Assche bart.vanassche@wdc.com Cc: Hannes Reinecke hare@suse.com Cc: Douglas Gilbert dgilbert@interlog.com Cc: Damien Le Moal damien.lemoal@wdc.com Cc: Christoph Hellwig hch@lst.de Cc: stable@vger.kernel.org
Changes compared to v1:
- Modified __scsi_error_from_host_byte() such that it again returns BLK_STS_OK for CONDITION MET and other result codes that represent success.
drivers/scsi/scsi_lib.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 74a39db57d49..1496b34af409 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -736,7 +736,13 @@ static blk_status_t __scsi_error_from_host_byte(struct scsi_cmnd *cmd, { switch (host_byte(result)) { case DID_OK:
return BLK_STS_OK;
/** Also check the other bytes than the status bytein result
* to handle the case when a SCSI LLD sets result to* DRIVER_SENSE << 24 without settingSAM_STAT_CHECK_CONDITION.
*/return scsi_status_is_good(result) && (result &~0xff) == 0 ?
BLK_STS_OK : BLK_STS_IOERR;
And a further nit-pick: the function is called __scsi_error_from_host_byte(), so it's only logical that it would only check the host_byte(). What's wrong is the _usage_ here; after calling __scsi_error_from_host_byte() we need to check if the _other_ bits of the results are non-zero to end up with a valid result.
Hence I would advocate to either rename this function (__scsi_error_from_result() ?) or evaluate the remaining bits outside this function.
But I would advocate for the former; otherwise the same issue will crop up again in the future.
Cheers,
Hannes