On 2018-04-04 12:30 PM, Bart Van Assche wrote:
The description of commit e39a97353e53 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, that commit introduced a severe bug: it causes commands that fail with hostbyte=DID_OK and driverbyte=DRIVER_SENSE to be completed with BLK_STS_OK. Although that commit claims to fix a bug it does not mention which bug it fixes. Hence revert that commit.
That patch arose from the thread started by me titled: [PATCH v2] Make SCSI Status CONDITION MET equivalent to GOOD on 26 February this year. Hannes Reinecke made the case for reducing the helper scsi_io_completion_nz_result() to a single returned value (an idea that was applied and later reverted). He wrote:
Hmm. Can't we return blk_stat from this function, and adjusting the 'result' value after it with an if-clause like
if (blk_stat == BLK_STS_OK) result = 0;
That would cleanup up the function and avoid having (essentially) two return values.
The only problem here is that __scsi_error_from_hostbyte() will return BLK_STS_IOERR if result == 0; doubt that is intended. And I guess it'll affect this issue, too.
Mind sending a separate patch for that?
Actually Hannes had already sent a patch for that before I had time to react (on the same day). That is the patch you now plan to revert.
In Hannes' defence (and I reviewed it) it is counter intuitive that for callers to work properly, this function supplied with DID_OK in the result argument should return BLK_STS_IOERR.
Please find out why that is so and craft a comment so nobody else falls down this particular rabbit hole. Plus add 'case DID_OK:' before the 'default:' to emphasis the point.
Doug Gilbert
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
drivers/scsi/scsi_lib.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 74a39db57d49..71f5b010684c 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -735,8 +735,6 @@ static blk_status_t __scsi_error_from_host_byte(struct scsi_cmnd *cmd, int result) { switch (host_byte(result)) {
- case DID_OK:
return BLK_STS_OK;