On Wed, 2017-05-24 at 17:28 -0500, Mike Christie wrote:
> On 05/23/2017 06:48 PM, Bart Van Assche wrote:
> > Introduce a function that sends the SCSI status "BUSY" back to the
> > initiator.
> >
> > Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxxxxxx>
> > Reviewed-by: Hannes Reinecke <hare@xxxxxxxx>
> > Cc: Christoph Hellwig <hch@xxxxxx>
> > Cc: Andy Grover <agrover@xxxxxxxxxx>
> > Cc: David Disseldorp <ddiss@xxxxxxx>
> > ---
> > drivers/target/target_core_transport.c | 10 ++++++++++
> > include/target/target_core_fabric.h | 1 +
> > 2 files changed, 11 insertions(+)
> >
> > diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
> > index cfe69c1fc879..c28e3b58150b 100644
> > --- a/drivers/target/target_core_transport.c
> > +++ b/drivers/target/target_core_transport.c
> > @@ -3130,6 +3130,16 @@ transport_send_check_condition_and_sense(struct se_cmd *cmd,
> > }
> > EXPORT_SYMBOL(transport_send_check_condition_and_sense);
> >
> > +int target_send_busy(struct se_cmd *cmd)
> > +{
> > + WARN_ON_ONCE(cmd->se_cmd_flags & SCF_SCSI_TMR_CDB);
> > +
> > + cmd->scsi_status = SAM_STAT_BUSY;
> > + trace_target_cmd_complete(cmd);
> > + return cmd->se_tfo->queue_status(cmd);
> > +}
>
> Hey,
>
> How are drivers supposed to handler queue_status failures or should that
> not happen when this is called?
>
> If it can happen, do they just drop the command? Is the tmr code able to
> figure this out? Will it not even be on the sess_cmd_list so would hit
> the does not exist tmr abort code path, or will it just sit in
> transport_wait_for_tasks? Are drivers supposed to call
> transport_handle_queue_full to queue up retrying sending something?
Hello Mike,
This function is intended to be used only if target_submit_cmd*() fails.
If target_submit_cmd*() fails se_cmd won't be on sess_cmd_list.
If the .queue_status() call from target_send_busy() fails it is safe to
ignore that failure because the initiator will resend the command anyway
after the command timeout has expired.
The function transport_handle_queue_full() is intended for commands that
have been submitted to the target core through target_submit_cmd*(). I
don't think it is safe to call that function if target_submit_cmd*() failed.
Bart.--
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