Tejun Heo wrote:
> PIO executes without holding host_set lock, so it cannot be
> synchronized using the same mechanism as interrupt driven execution.
> port_task framework makes sure that EH is not entered until PIO task
> is flushed, so PIO task can be sure the qc in progress won't go away
> underneath it. One thing it cannot be sure of is whether the qc has
> already been scheduled for EH by another exception condition while
> host_set lock was released.
>
> This patch makes ata_poll_qc-complete() handle such conditions
> properly and make it freeze the port if HSM violation is detected
> during PIO execution.
>
> Signed-off-by: Tejun Heo <htejun@xxxxxxxxx>
>
> ---
>
> drivers/scsi/libata-core.c | 23 +++++++++++++++++++----
> 1 files changed, 19 insertions(+), 4 deletions(-)
>
> 52240d1d208615e461c41a5c297f521a8a892f0d
> diff --git a/drivers/scsi/libata-core.c b/drivers/scsi/libata-core.c
> index 436ff5b..86d6a7d 100644
> --- a/drivers/scsi/libata-core.c
> +++ b/drivers/scsi/libata-core.c
> @@ -3429,16 +3429,31 @@ skip_map:
> * LOCKING:
> * None. (grabs host lock)
> */
> -
> void ata_poll_qc_complete(struct ata_queued_cmd *qc)
> {
> struct ata_port *ap = qc->ap;
> unsigned long flags;
>
> spin_lock_irqsave(&ap->host_set->lock, flags);
> - ap->flags &= ~ATA_FLAG_NOINTR;
> - ata_irq_on(ap);
> - ata_qc_complete(qc);
> +
> + if (ap->ops->error_handler) {
> + /* EH might have kicked in while host_set lock is released */
> + qc = ata_qc_from_tag(ap, qc->tag);
> + if (qc) {
> + if (!(qc->err_mask & AC_ERR_HSM)) {
> + ap->flags &= ~ATA_FLAG_NOINTR;
> + ata_irq_on(ap);
> + ata_qc_complete(qc);
> + } else
> + ata_port_freeze(ap);
I don't quite understand here. For the AC_ERR_HSM error, how does the
EH get triggered after ata_port_freeze()? Do we wait until time out?
> + }
> + } else {
> + /* old EH */
> + ap->flags &= ~ATA_FLAG_NOINTR;
> + ata_irq_on(ap);
> + ata_qc_complete(qc);
> + }
> +
> spin_unlock_irqrestore(&ap->host_set->lock, flags);
> }
>
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