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SubjectRe: [PATCH] ata:libata-eh:Cleanup ata_scsi_cmd_error_handler
Date
On Thu, Dec 15, 2022 at 01:04:16PM +0800, Wenchao Hao wrote:
> If ap->ops->error_handler is NULL, just go out and release the
> spinlock. This patch is just a cleanup, which would not change
> the origin error handle logic.
>
> Signed-off-by: Wenchao Hao <haowenchao@huawei.com>
> ---
> drivers/ata/libata-eh.c | 96 ++++++++++++++++++++---------------------
> 1 file changed, 48 insertions(+), 48 deletions(-)
>
> diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
> index 34303ce67c14..66ca3ac7cd58 100644
> --- a/drivers/ata/libata-eh.c
> +++ b/drivers/ata/libata-eh.c
> @@ -565,6 +565,8 @@ void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap,
> {
> int i;
> unsigned long flags;
> + struct scsi_cmnd *scmd, *tmp;
> + int nr_timedout = 0;
>
> /* make sure sff pio task is not running */
> ata_sff_flush_pio_task(ap);
> @@ -584,62 +586,60 @@ void ata_scsi_cmd_error_handler(struct Scsi_Host *host, struct ata_port *ap,
> * timed out iff its associated qc is active and not failed.
> */
> spin_lock_irqsave(ap->lock, flags);
> - if (ap->ops->error_handler) {
> - struct scsi_cmnd *scmd, *tmp;
> - int nr_timedout = 0;
> -
> - /* This must occur under the ap->lock as we don't want
> - a polled recovery to race the real interrupt handler
> -
> - The lost_interrupt handler checks for any completed but
> - non-notified command and completes much like an IRQ handler.
> -
> - We then fall into the error recovery code which will treat
> - this as if normal completion won the race */
> + if (!ap->ops->error_handler)
> + goto out;

Nice cleanup!

However, I don't think there is any point in taking the spin lock if there is
no error_handler.

So I think that you can do similar to the skip_eh label in ata_port_detach():
https://github.com/torvalds/linux/blob/master/drivers/ata/libata-core.c#L5904


Kind regards,
Niklas

>
> - if (ap->ops->lost_interrupt)
> - ap->ops->lost_interrupt(ap);
> + /* This must occur under the ap->lock as we don't want
> + * a polled recovery to race the real interrupt handler
> + *
> + * The lost_interrupt handler checks for any completed but
> + * non-notified command and completes much like an IRQ handler.
> + *
> + * We then fall into the error recovery code which will treat
> + * this as if normal completion won the race
> + */
> + if (ap->ops->lost_interrupt)
> + ap->ops->lost_interrupt(ap);
>
> - list_for_each_entry_safe(scmd, tmp, eh_work_q, eh_entry) {
> - struct ata_queued_cmd *qc;
> + list_for_each_entry_safe(scmd, tmp, eh_work_q, eh_entry) {
> + struct ata_queued_cmd *qc;
>
> - ata_qc_for_each_raw(ap, qc, i) {
> - if (qc->flags & ATA_QCFLAG_ACTIVE &&
> - qc->scsicmd == scmd)
> - break;
> - }
> + ata_qc_for_each_raw(ap, qc, i) {
> + if (qc->flags & ATA_QCFLAG_ACTIVE &&
> + qc->scsicmd == scmd)
> + break;
> + }
>
> - if (i < ATA_MAX_QUEUE) {
> - /* the scmd has an associated qc */
> - if (!(qc->flags & ATA_QCFLAG_FAILED)) {
> - /* which hasn't failed yet, timeout */
> - qc->err_mask |= AC_ERR_TIMEOUT;
> - qc->flags |= ATA_QCFLAG_FAILED;
> - nr_timedout++;
> - }
> - } else {
> - /* Normal completion occurred after
> - * SCSI timeout but before this point.
> - * Successfully complete it.
> - */
> - scmd->retries = scmd->allowed;
> - scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
> + if (i < ATA_MAX_QUEUE) {
> + /* the scmd has an associated qc */
> + if (!(qc->flags & ATA_QCFLAG_FAILED)) {
> + /* which hasn't failed yet, timeout */
> + qc->err_mask |= AC_ERR_TIMEOUT;
> + qc->flags |= ATA_QCFLAG_FAILED;
> + nr_timedout++;
> }
> + } else {
> + /* Normal completion occurred after
> + * SCSI timeout but before this point.
> + * Successfully complete it.
> + */
> + scmd->retries = scmd->allowed;
> + scsi_eh_finish_cmd(scmd, &ap->eh_done_q);
> }
> + }
>
> - /* If we have timed out qcs. They belong to EH from
> - * this point but the state of the controller is
> - * unknown. Freeze the port to make sure the IRQ
> - * handler doesn't diddle with those qcs. This must
> - * be done atomically w.r.t. setting QCFLAG_FAILED.
> - */
> - if (nr_timedout)
> - __ata_port_freeze(ap);
> -
> + /* If we have timed out qcs. They belong to EH from
> + * this point but the state of the controller is
> + * unknown. Freeze the port to make sure the IRQ
> + * handler doesn't diddle with those qcs. This must
> + * be done atomically w.r.t. setting QCFLAG_FAILED.
> + */
> + if (nr_timedout)
> + __ata_port_freeze(ap);
>
> - /* initialize eh_tries */
> - ap->eh_tries = ATA_EH_MAX_TRIES;
> - }
> + /* initialize eh_tries */
> + ap->eh_tries = ATA_EH_MAX_TRIES;
> +out:
> spin_unlock_irqrestore(ap->lock, flags);
>
> }
> --
> 2.32.0
>
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