3.16.52-rc1 review patch. If anyone has any objections, please let me know.
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From: Alan Stern stern@rowland.harvard.edu
commit a4fd4a724d6c30ad671046d83be2e9be2f11d275 upstream.
Ever since commit a621bac3044e ("scsi_lib: correctly retry failed zero length REQ_TYPE_FS commands"), people have been getting bogus error messages for USB disk drives using ATA pass-thru. For example:
[ 1344.880193] sd 6:0:0:0: [sdb] Attached SCSI disk [ 1345.069152] sd 6:0:0:0: [sdb] tag#0 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE [ 1345.069159] sd 6:0:0:0: [sdb] tag#0 Sense Key : Hardware Error [current] [descriptor] [ 1345.069162] sd 6:0:0:0: [sdb] tag#0 Add. Sense: No additional sense information [ 1345.069168] sd 6:0:0:0: [sdb] tag#0 CDB: ATA command pass through(16) 85 06 20 00 00 00 00 00 00 00 00 00 00 00 e5 00 [ 1345.172252] sd 6:0:0:0: [sdb] tag#0 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE [ 1345.172258] sd 6:0:0:0: [sdb] tag#0 Sense Key : Hardware Error [current] [descriptor] [ 1345.172261] sd 6:0:0:0: [sdb] tag#0 Add. Sense: No additional sense information [ 1345.172266] sd 6:0:0:0: [sdb] tag#0 CDB: ATA command pass through(12)/Blank a1 06 20 da 00 00 4f c2 00 b0 00 00
These messages can be quite annoying, because programs like udisks2 provoke them every 10 minutes or so. Other programs can also have this effect, such as those in smartmontools.
I don't fully understand how that commit induced the SCSI core to log these error messages, but the underlying cause for them is code added to usb-storage by commit f1a0743bc0e7 ("USB: storage: When a device returns no sense data, call it a Hardware Error"). At the time it was necessary to do this, in order to prevent an infinite retry loop with some not-so-great mass storage devices.
However, the ATA pass-thru protocol uses SCSI sense data to return command status values, and some devices always report Check Condition status for ATA pass-thru commands to ensure that the host retrieves the sense data, even if the command succeeded. This violates the USB mass-storage protocol (Check Condition status is supposed to mean the command failed), but we can't help that.
This patch attempts to mitigate the problem of these bogus error reports by changing usb-storage. The HARDWARE ERROR sense key will be inserted only for commands that aren't ATA pass-thru.
Thanks to Ewan Milne for pointing out that this mechanism was present in usb-storage. 8 years after writing it, I had completely forgotten its existence.
Signed-off-by: Alan Stern stern@rowland.harvard.edu Tested-by: Kris Lindgren kris.lindgren@gmail.com Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1351305 CC: Ewan D. Milne emilne@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org [bwh: Backported to 3.16: adjust context] Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/usb/storage/transport.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
--- a/drivers/usb/storage/transport.c +++ b/drivers/usb/storage/transport.c @@ -808,12 +808,24 @@ Retry_Sense: if (result == USB_STOR_TRANSPORT_GOOD) { srb->result = SAM_STAT_GOOD; srb->sense_buffer[0] = 0x0; + } + + /* + * ATA-passthru commands use sense data to report + * the command completion status, and often devices + * return Check Condition status when nothing is + * wrong. + */ + else if (srb->cmnd[0] == ATA_16 || + srb->cmnd[0] == ATA_12) { + /* leave the data alone */ + }
/* If there was a problem, report an unspecified * hardware error to prevent the higher layers from * entering an infinite retry loop. */ - } else { + else { srb->result = DID_ERROR << 16; if ((sshdr.response_code & 0x72) == 0x72) srb->sense_buffer[1] = HARDWARE_ERROR;