On Thu, 2017-05-18 at 11:34 -0400, Ewan D. Milne wrote: > On Thu, 2017-05-18 at 10:35 -0400, Alan Stern wrote: > > This is in reference to > > > > https://bugzilla.redhat.com/show_bug.cgi?id=1351305 > > > > The problem is that some program (probably udisks2) periodically sends > > the following ATA pass-through command to a USB-ATA bridge attached to > > a Western Digital drive: > > > > 85062000 00000000 00000000 0000e500 > > According to T10 SAT-4 this is an ATA PASS-THROUGH(16) command, with > PROTOCOL=3 (non-data), CK_COND=1, COMMAND=E5h (the ATA command). > > > > > I don't know what this command does (some sort of reset?). The command > > fails and the device returns the following sense data: > > > > 72000000 0000000e 090c0000 00ff0000 00000000 0050 > > > > I don't know how to decode this -- I don't have copies of the relevant > > documents. Can anybody decode this for me? > > This is a current descriptor format sense data wih a single > ATA Status Return sense data descriptor (beginning at 8 bytes into > the sense data buffer 090c...) The relevant fields are COUNT=255 LBA=0 > and STATUS=50h (which I suspect is what is the interesting part). > > > > > Anyway, the SCSI core treats it as a Hardware Error and puts warning > > messages in the kernel log: > > > > [17244.280612] sd 7:0:0:0: [sdd] tag#0 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_SENSE > > [17244.280614] sd 7:0:0:0: [sdd] tag#0 Sense Key : Hardware Error [current] [descriptor] > > [17244.280616] sd 7:0:0:0: [sdd] tag#0 Add. Sense: No additional sense information > > [17244.280618] sd 7:0:0:0: [sdd] tag#0 CDB: ATA command pass through(16) 85 06 20 00 00 00 00 00 00 00 00 00 00 00 e5 00 > > > > Is this really the right thing to do? Could it be that we are failing > > to interpret this sense data correctly? > > With the 72000000 0000000e 090c0000 00ff0000 00000000 0050 sense data > buffer above scsi_sense_key_string() should have returned "No Sense" as > the array value is 0. Even if we somehow managed to fail to correctly > interpret descriptor format sense vs. fixed format sense. > > > > > Other commands provoke similar responses from the device, but without > > obnoxious log messages. For example, the command: > > > > 85082e00 00000100 00000000 0000ec00 > > > > fails with the following sense data: > > > > 72000000 0000000e 090c0000 00000000 00000000 0050 > > > > and no output to the log. I don't know why the behavior is different. > > There are other similar examples, with and without log messages. > > It seems more likely that somehow there is a path where the wrong or > uninitialized sshdr structure is being passed to the logging routine. > > -Ewan Oh, wait. You said USB-ATA bridge. There is this code in drivers/usb/storage/transport.c: Perhaps this is responsible. It is forcing the sense key to HARDWARE_ERROR under certain conditions. That would cause the logging message you see to be output. /* * We often get empty sense data. This could indicate that * everything worked or that there was an unspecified * problem. We have to decide which. */ if (sshdr.sense_key == 0 && sshdr.asc == 0 && sshdr.ascq == 0 && fm_ili == 0) { /* * If things are really okay, then let's show that. * Zero out the sense buffer so the higher layers * won't realize we did an unsolicited auto-sense. */ if (result == USB_STOR_TRANSPORT_GOOD) { srb->result = SAM_STAT_GOOD; srb->sense_buffer[0] = 0x0; /* * If there was a problem, report an unspecified * hardware error to prevent the higher layers from * entering an infinite retry loop. */ } else { srb->result = DID_ERROR << 16; if ((sshdr.response_code & 0x72) == 0x72) srb->sense_buffer[1] = HARDWARE_ERROR; else srb->sense_buffer[2] = HARDWARE_ERROR; } } > > > > > Any help would be appreciated. > > > > Alan Stern > > > >
