Re: [PATCH RFC v3 1/7] ata: libata-scsi: Add ata_scsi_queue_internal()

Damien Le Moal
2022-10-27T01:42:51Z

On 10/25/22 19:32, John Garry wrote:
> Add a function to handle queued ATA internal SCSI cmnds - does much the
> same as ata_exec_internal_sg() does (which will be fixed up later to
> actually queue internal cmnds through this function).
>
> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
> drivers/ata/libata-sata.c | 3 +++
> drivers/ata/libata-scsi.c | 43 +++++++++++++++++++++++++++++++++++++++
> drivers/ata/libata.h | 3 ++-
> include/linux/libata.h | 6 ++++++
> 4 files changed, 54 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
> index b6806d41a8c5..e8b828c56542 100644
> --- a/drivers/ata/libata-sata.c
> +++ b/drivers/ata/libata-sata.c
> @@ -1258,6 +1258,9 @@ int ata_sas_queuecmd(struct scsi_cmnd *cmd, struct ata_port *ap)
> {
> int rc = 0;
>
> + if (blk_mq_is_reserved_rq(scsi_cmd_to_rq(cmd)))
> + return ata_scsi_queue_internal(cmd, ap->link.device);
> +
> if (likely(ata_dev_enabled(ap->link.device)))
> rc = __ata_scsi_queuecmd(cmd, ap->link.device);
> else {
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 476e0ef4bd29..30d7c90b0c35 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -3965,6 +3965,49 @@ static inline ata_xlat_func_t ata_get_xlat_func(struct ata_device *dev, u8 cmd)
> return NULL;
> }
>
> +unsigned int ata_scsi_queue_internal(struct scsi_cmnd *scmd,
> + struct ata_device *dev)
> +{
> + struct ata_link *link = dev->link;
> + struct ata_port *ap = link->ap;
> + struct ata_queued_cmd *qc;
> +
> + /* no internal command while frozen */
> + if (ap->pflags & ATA_PFLAG_FROZEN)
> + goto did_err;
> +
> + /* initialize internal qc */
> + qc = __ata_qc_from_tag(ap, ATA_TAG_INTERNAL);
> + link->preempted_tag = link->active_tag;
> + link->preempted_sactive = link->sactive;
> + ap->preempted_qc_active = ap->qc_active;
> + ap->preempted_nr_active_links = ap->nr_active_links;
> + link->active_tag = ATA_TAG_POISON;
> + link->sactive = 0;
> + ap->qc_active = 0;
> + ap->nr_active_links = 0;
> +
> + if (qc->dma_dir != DMA_NONE) {
> + int n_elem;
> +
> + n_elem = 1;
> + qc->n_elem = n_elem;
> + qc->sg = scsi_sglist(scmd);
> + qc->nbytes = qc->sg->length;
> + ata_sg_init(qc, qc->sg, n_elem);
> + }
> +
> + scmd->submitter = SUBMITTED_BY_BLOCK_LAYER;
> +
> + ata_qc_issue(qc);

Arg, no ! This potentially mixes NCQ and non-NCQ commands, which is
forbidden by ATA spec. You need to use something like:

if (ap->ops->qc_defer) {
if ((rc = ap->ops->qc_defer(qc)))
goto defer;
}

ata_qc_issue(qc);

which is done in __ata_scsi_queuecmd() -> ata_scsi_translate()

Unless you guarantee that ata_scsi_queue_internal() is always called
from libata EH context ?

> +
> + return 0;
> +did_err:
> + scmd->result = (DID_ERROR << 16);
> + scsi_done(scmd);
> + return 0;
> +}
> +
> int __ata_scsi_queuecmd(struct scsi_cmnd *scmd, struct ata_device *dev)
> {
> u8 scsi_op = scmd->cmnd[0];
> diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
> index 0c2df1e60768..15cd1cd618b8 100644
> --- a/drivers/ata/libata.h
> +++ b/drivers/ata/libata.h
> @@ -82,7 +82,6 @@ extern int ata_port_probe(struct ata_port *ap);
> extern void __ata_port_probe(struct ata_port *ap);
> extern unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
> u8 page, void *buf, unsigned int sectors);
> -
> #define to_ata_port(d) container_of(d, struct ata_port, tdev)
>
> /* libata-acpi.c */
> @@ -130,6 +129,8 @@ extern int ata_scsi_user_scan(struct Scsi_Host *shost, unsigned int channel,
> void ata_scsi_sdev_config(struct scsi_device *sdev);
> int ata_scsi_dev_config(struct scsi_device *sdev, struct ata_device *dev);
> int __ata_scsi_queuecmd(struct scsi_cmnd *scmd, struct ata_device *dev);
> +unsigned int ata_scsi_queue_internal(struct scsi_cmnd *scmd,
> + struct ata_device *dev);
>
> /* libata-eh.c */
> extern unsigned int ata_internal_cmd_timeout(struct ata_device *dev, u8 cmd);
> diff --git a/include/linux/libata.h b/include/linux/libata.h
> index 827d5838cd23..8938b584520f 100644
> --- a/include/linux/libata.h
> +++ b/include/linux/libata.h
> @@ -764,7 +764,9 @@ struct ata_link {
>
> struct device tdev;
> unsigned int active_tag; /* active tag on this link */
> + unsigned int preempted_tag;
> u32 sactive; /* active NCQ commands */
> + u32 preempted_sactive;
>
> unsigned int flags; /* ATA_LFLAG_xxx */
>
> @@ -857,6 +859,10 @@ struct ata_port {
> #ifdef CONFIG_ATA_ACPI
> struct ata_acpi_gtm __acpi_init_gtm; /* use ata_acpi_init_gtm() */
> #endif
> +
> + u64 preempted_qc_active;
> + int preempted_nr_active_links;
> +
> /* owned by EH */
> u8 sector_buf[ATA_SECT_SIZE] ____cacheline_aligned;
> };

--
Damien Le Moal
Western Digital Research