On 08/25/2014 01:15 PM, Paolo Bonzini wrote:
Il 25/08/2014 12:28, Bart Van Assche ha scritto:
From SPC-4: "7.5.8 Control mode page [ ... ] A task aborted status (TAS)
bit set to zero specifies that aborted commands shall be terminated by
the device server without any response to the application client. A TAS
bit set to one specifies that commands aborted by the actions of an I_T
nexus other than the I_T nexus on which the command was received shall
be completed with TASK ABORTED status (see SAM-5)."
Note the "aborted by the actions of an I_T nexus other than the I_T
nexus on which the command was received".
In practice, this means that TASK ABORTED should only happen if you use
the CLEAR TASK SET tmf and TST is not set to 001b (i.e. _not_ to "per
I_T nexus") in the Control mode page. It should never happen for a pen
drive.
Setting TASK ABORTED aside, the important part is that an abort can do
one of two things:
- complete the command, and then eh_abort should return after the driver
has noticed the completion and called the ->scsi_done callback for the
Scsi_Cmnd*.
- abort the command, and then the driver should never call the
->scsi_done callback for the Scsi_Cmnd*.
In practice we rely on the latter behaviour; when ->scsi_done is
called while the command is under eh_abort _really bad things_
will happen.
As soon as eh_abort is called control is transferred back to the
SCSI midlayer, so any LLDD should never send completions for these
commands back to the midlayer.
Cheers,
Hannes
--
Dr. Hannes Reinecke zSeries & Storage
hare@xxxxxxx +49 911 74053 688
SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: J. Hawn, J. Guild, F. Imendörffer, HRB 16746 (AG Nürnberg)
--
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
