Albert Lee wrote:
> Jeff,
> 
> During PIO, after calling ata_poll_qc_complete(), the next command might be
> running and the value of 'ap->pio_task_state' might have been changed.
> Accessing 'ap->pio_task_state' is not safe at this point.
> 
> Ex.
> qc 1 completed. queuing a final task with ap->pio_task_state == 
> PIO_ST_IDLE.
> qc 2 started, queuing a new task with ap->pio_task_state set to PIO_ST.
> qc 1 read ap->pio_task_state as PIO_ST; not PIO_ST_IDLE as expected.
> => 2 qc running in the workqueue with pio_task_state PIO_ST.
> 
> Changes:
>  1/2: Modify ata_pio_complete() and ata_pio_block() to return
>       whether qc has been completed.
> 
>  2/2: Modify ata_pio_task() to check the return value. Only queue next 
> step and
>        access 'ap->pio_task_state' if the command is not completed.

I would prefer something more like the attached patch.  This patch does 
two things:
* eliminate needless queueing
* don't race with qc-complete in ata_pio_complete()

This patch is COMPLETELY UNTESTED.  Please use the attached as a base, 
to replace the patch series you have submitted.  I won't check it in, as 
I would like to hear feedback and get some review.

	Jeff