Re: Error handling in LibATA

[Douglas Gilbert <dougg@torque.net>]

John Treubig wrote:
> I've been working on a problem with Promise 20269 PATA adapter under
> LibATA that if the drive has a write error or time-out, the application
> that is accessing the drive using SG should see some sort of error.  My
> first problem was my system hung.  After patching the IDE-IO.C, with a
> recognized patch, I have been able to keep my system from hanging.  Now
> the only problem is the application gets no notification that the drive
> has been rendered inaccessible.  (Test case is to run a system with my
> app going, and then pull the power from the drive.  System log shows the
> errors, but nothing gets back to the app).  The app does get
> notifications if I perform the same type of test on a drive attached to
> the motherboard secondary IDE adapter, so we know the app is correctly
> implemented.
> 
> I've traced the errors down to the fact that the errors are caught in
> libata-core.c (ata_qc_timeout).  I'd like to put a call in libata-core.c
> that would cause an error to be reflected back to the application.  Can
> you suggest the function or method that would do this?

John,
SG_IO ioctl users would normally expect to see DRIVER_TIMEOUT
(plus a suggest mask) in sg_io_hdr::driver_status when a
mid level timeout goes off. So that needs to be "wired"
in libata (along with some other transport errors I suspect).

Here is an example of a timeout using the scsi_debug driver:
# modprobe scsi_debug ptype=9 delay=200000
# lsscsi -g
[0:0:0:0]    comms   Linux    scsi_debug       0004  -         /dev/sg0
# sg_start /dev/sg0
start stop unit: transport: Driver_status=0x06 [DRIVER_TIMEOUT, SUGGEST_OK]
START STOP UNIT command failed


Doug Gilbert