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SubjectRe: [PATCH v2 2/2] libata: Inline ata_qc_new_init() in ata_scsi_qc_new()
From
On 4/4/22 23:53, John Garry wrote:
> From: Christoph Hellwig <hch@lst.de>
>
> It is a bit pointless to have ata_qc_new_init() in libata-core.c since it
> pokes scsi internals, so inline it in ata_scsi_qc_new() (in libata-scsi.c).
>
> <Christoph, please provide signed-off-by>
> [jpg, Take Christoph's change from list and form into a patch]
> Signed-off-by: John Garry <john.garry@huawei.com>
> ---
> Documentation/driver-api/libata.rst | 11 -------
> drivers/ata/libata-core.c | 44 +---------------------------
> drivers/ata/libata-sata.c | 8 -----
> drivers/ata/libata-scsi.c | 45 ++++++++++++++++++++++-------
> drivers/ata/libata.h | 12 --------
> 5 files changed, 35 insertions(+), 85 deletions(-)
>
> diff --git a/Documentation/driver-api/libata.rst b/Documentation/driver-api/libata.rst
> index d477e296bda5..311af516a3fd 100644
> --- a/Documentation/driver-api/libata.rst
> +++ b/Documentation/driver-api/libata.rst
> @@ -424,12 +424,6 @@ How commands are issued
> -----------------------
>
> Internal commands
> - First, qc is allocated and initialized using :c:func:`ata_qc_new_init`.
> - Although :c:func:`ata_qc_new_init` doesn't implement any wait or retry
> - mechanism when qc is not available, internal commands are currently
> - issued only during initialization and error recovery, so no other
> - command is active and allocation is guaranteed to succeed.
> -
> Once allocated qc's taskfile is initialized for the command to be
> executed. qc currently has two mechanisms to notify completion. One
> is via ``qc->complete_fn()`` callback and the other is completion
> @@ -447,11 +441,6 @@ SCSI commands
> translated. No qc is involved in processing a simulated scmd. The
> result is computed right away and the scmd is completed.
>
> - For a translated scmd, :c:func:`ata_qc_new_init` is invoked to allocate a
> - qc and the scmd is translated into the qc. SCSI midlayer's
> - completion notification function pointer is stored into
> - ``qc->scsidone``.
> -
> ``qc->complete_fn()`` callback is used for completion notification. ATA
> commands use :c:func:`ata_scsi_qc_complete` while ATAPI commands use
> :c:func:`atapi_qc_complete`. Both functions end up calling ``qc->scsidone``
> diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
> index 1067b2e2be28..5e7d6ccad5da 100644
> --- a/drivers/ata/libata-core.c
> +++ b/drivers/ata/libata-core.c
> @@ -4563,43 +4563,6 @@ void swap_buf_le16(u16 *buf, unsigned int buf_words)
> #endif /* __BIG_ENDIAN */
> }
>
> -/**
> - * ata_qc_new_init - Request an available ATA command, and initialize it
> - * @dev: Device from whom we request an available command structure
> - * @scmd: scmd for which to get qc
> - *
> - * LOCKING:
> - * None.
> - */
> -
> -struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, struct scsi_cmnd *scmd)
> -{
> - int tag = scsi_cmd_to_rq(scmd)->tag;
> - struct ata_port *ap = dev->link->ap;
> - struct ata_queued_cmd *qc;
> -
> - /* no command while frozen */
> - if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
> - return NULL;
> -
> - /* libsas case */
> - if (ap->flags & ATA_FLAG_SAS_HOST) {
> - tag = ata_sas_get_tag(scmd);
> - if (tag < 0)
> - return NULL;
> - }
> -
> - qc = __ata_qc_from_tag(ap, tag);
> - qc->tag = qc->hw_tag = tag;
> - qc->scsicmd = NULL;
> - qc->ap = ap;
> - qc->dev = dev;
> -
> - ata_qc_reinit(qc);
> -
> - return qc;
> -}
> -
> /**
> * ata_qc_free - free unused ata_queued_cmd
> * @qc: Command to complete
> @@ -4612,13 +4575,8 @@ struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, struct scsi_cmnd
> */
> void ata_qc_free(struct ata_queued_cmd *qc)
> {
> - unsigned int tag;
> -
> - WARN_ON_ONCE(qc == NULL); /* ata_qc_from_tag _might_ return NULL */
> -
> qc->flags = 0;
> - tag = qc->tag;
> - if (ata_tag_valid(tag))
> + if (ata_tag_valid(qc->tag))
> qc->tag = ATA_TAG_POISON;
> }
>
> diff --git a/drivers/ata/libata-sata.c b/drivers/ata/libata-sata.c
> index c3e9fd7d920c..7a5fe41aa5ae 100644
> --- a/drivers/ata/libata-sata.c
> +++ b/drivers/ata/libata-sata.c
> @@ -1268,14 +1268,6 @@ int ata_sas_queuecmd(struct scsi_cmnd *cmd, struct ata_port *ap)
> }
> EXPORT_SYMBOL_GPL(ata_sas_queuecmd);
>
> -int ata_sas_get_tag(struct scsi_cmnd *scmd)
> -{
> - if (WARN_ON_ONCE(scmd->budget_token >= ATA_MAX_QUEUE))
> - return -1;
> -
> - return scmd->budget_token;
> -}
> -
> /**
> * sata_async_notification - SATA async notification handler
> * @ap: ATA port where async notification is received
> diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
> index 61dd7f7c7743..50ef132ec48c 100644
> --- a/drivers/ata/libata-scsi.c
> +++ b/drivers/ata/libata-scsi.c
> @@ -638,24 +638,47 @@ EXPORT_SYMBOL_GPL(ata_scsi_ioctl);
> static struct ata_queued_cmd *ata_scsi_qc_new(struct ata_device *dev,
> struct scsi_cmnd *cmd)
> {
> + struct ata_port *ap = dev->link->ap;
> struct ata_queued_cmd *qc;
> + int tag;
>
> - qc = ata_qc_new_init(dev, cmd);
> - if (qc) {
> - qc->scsicmd = cmd;
> - qc->scsidone = scsi_done;
> -
> - qc->sg = scsi_sglist(cmd);
> - qc->n_elem = scsi_sg_count(cmd);
> + if (unlikely(ap->pflags & ATA_PFLAG_FROZEN))
> + goto fail;
>
> - if (scsi_cmd_to_rq(cmd)->rq_flags & RQF_QUIET)
> - qc->flags |= ATA_QCFLAG_QUIET;
> + if (ap->flags & ATA_FLAG_SAS_HOST) {
> + /*
> + * SAS hosts may queue > ATA_MAX_QUEUE commands so use
> + * unique per-device budget token as a tag.
> + */
> + if (WARN_ON_ONCE(cmd->budget_token >= ATA_MAX_QUEUE))
> + goto fail;
> + tag = cmd->budget_token;
> } else {
> - cmd->result = (DID_OK << 16) | SAM_STAT_TASK_SET_FULL;
> - scsi_done(cmd);
> + tag = scsi_cmd_to_rq(cmd)->tag;
> }
>
> + qc = __ata_qc_from_tag(ap, tag);
> + qc->tag = qc->hw_tag = tag;
> + qc->scsicmd = NULL;
> + qc->ap = ap;
> + qc->dev = dev;
> +
> + ata_qc_reinit(qc);
> +
> + qc->scsicmd = cmd;
> + qc->scsidone = scsi_done;
> +
> + qc->sg = scsi_sglist(cmd);
> + qc->n_elem = scsi_sg_count(cmd);
> +
> + if (scsi_cmd_to_rq(cmd)->rq_flags & RQF_QUIET)
> + qc->flags |= ATA_QCFLAG_QUIET;

Please add a blank line here.
I like to have return statements stand out :)

> return qc;
> +
> +fail:
> + cmd->result = (DID_OK << 16) | SAM_STAT_TASK_SET_FULL;

While at it, it may be better to use:

set_host_byte(cmd, DID_OK);
set_status_byte(cmd, SAM_STAT_TASK_SET_FULL);

> + scsi_done(cmd);
> + return NULL;
> }
>
> static void ata_qc_set_pc_nbytes(struct ata_queued_cmd *qc)
> diff --git a/drivers/ata/libata.h b/drivers/ata/libata.h
> index 92e52090165b..926a7f41303d 100644
> --- a/drivers/ata/libata.h
> +++ b/drivers/ata/libata.h
> @@ -44,7 +44,6 @@ static inline void ata_force_cbl(struct ata_port *ap) { }
> #endif
> extern u64 ata_tf_to_lba(const struct ata_taskfile *tf);
> extern u64 ata_tf_to_lba48(const struct ata_taskfile *tf);
> -extern struct ata_queued_cmd *ata_qc_new_init(struct ata_device *dev, struct scsi_cmnd *scmd);
> extern int ata_build_rw_tf(struct ata_taskfile *tf, struct ata_device *dev,
> u64 block, u32 n_block, unsigned int tf_flags,
> unsigned int tag, int class);
> @@ -91,17 +90,6 @@ extern unsigned int ata_read_log_page(struct ata_device *dev, u8 log,
>
> #define to_ata_port(d) container_of(d, struct ata_port, tdev)
>
> -/* libata-sata.c */
> -#ifdef CONFIG_SATA_HOST
> -int ata_sas_get_tag(struct scsi_cmnd *scmd);
> -#else
> -static inline int ata_sas_get_tag(struct scsi_cmnd *scmd)
> -{
> - return -EOPNOTSUPP;
> -}
> -static inline void ata_sas_free_tag(unsigned int tag, struct ata_port *ap) { }
> -#endif
> -
> /* libata-acpi.c */
> #ifdef CONFIG_ATA_ACPI
> extern unsigned int ata_acpi_gtf_filter;


--
Damien Le Moal
Western Digital Research

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