Commit 31cc23b3 authored by Tejun Heo's avatar Tejun Heo Committed by Jeff Garzik

libata-pmp-prep: implement ops->qc_defer()

Controllers which support PMP have various restrictions on which
combinations of commands are allowed to what number of devices
concurrently.  This patch implements ops->qc_defer() which determines
whether a qc can be issued at the moment or should be deferred.

If the function returns ATA_DEFER_LINK, the qc will be deferred until
a qc completes on the link.  If ATA_DEFER_PORT, until a qc completes
on any link.  The defer conditions are advisory and in general
ATA_DEFER_LINK can be considered as lower priority deferring than
ATA_DEFER_PORT.

ops->qc_defer() replaces fixed ata_scmd_need_defer().  For standard
NCQ/non-NCQ exclusion, ata_std_qc_defer() is implemented.  ahci and
sata_sil24 are converted to use ata_std_qc_defer().

ops->qc_defer() is heavier than the original mechanism because full qc
is prepped before determining to defer it, but various information is
needed to determine defer conditinos and fully translating a qc is the
only way to supply such information in generic manner.

IMHO, this shouldn't cause any noticeable performance issues as

* for most cases deferring occurs rarely (except for NCQ-aware
  cmd-switching PMP)
* translation itself isn't that expensive
* once deferred the command won't be repeated until another command
  completes which usually is a very long time cpu-wise.
Signed-off-by: default avatarTejun Heo <htejun@gmail.com>
Signed-off-by: default avatarJeff Garzik <jeff@garzik.org>
parent fb7fd614
......@@ -268,6 +268,7 @@ static const struct ata_port_operations ahci_ops = {
.tf_read = ahci_tf_read,
.qc_defer = ata_std_qc_defer,
.qc_prep = ahci_qc_prep,
.qc_issue = ahci_qc_issue,
......@@ -298,6 +299,7 @@ static const struct ata_port_operations ahci_vt8251_ops = {
.tf_read = ahci_tf_read,
.qc_defer = ata_std_qc_defer,
.qc_prep = ahci_qc_prep,
.qc_issue = ahci_qc_issue,
......
......@@ -4345,6 +4345,36 @@ int ata_check_atapi_dma(struct ata_queued_cmd *qc)
return 0;
}
/**
* ata_std_qc_defer - Check whether a qc needs to be deferred
* @qc: ATA command in question
*
* Non-NCQ commands cannot run with any other command, NCQ or
* not. As upper layer only knows the queue depth, we are
* responsible for maintaining exclusion. This function checks
* whether a new command @qc can be issued.
*
* LOCKING:
* spin_lock_irqsave(host lock)
*
* RETURNS:
* ATA_DEFER_* if deferring is needed, 0 otherwise.
*/
int ata_std_qc_defer(struct ata_queued_cmd *qc)
{
struct ata_link *link = qc->dev->link;
if (qc->tf.protocol == ATA_PROT_NCQ) {
if (!ata_tag_valid(link->active_tag))
return 0;
} else {
if (!ata_tag_valid(link->active_tag) && !link->sactive)
return 0;
}
return ATA_DEFER_LINK;
}
/**
* ata_qc_prep - Prepare taskfile for submission
* @qc: Metadata associated with taskfile to be prepared
......@@ -7111,6 +7141,7 @@ EXPORT_SYMBOL_GPL(ata_interrupt);
EXPORT_SYMBOL_GPL(ata_do_set_mode);
EXPORT_SYMBOL_GPL(ata_data_xfer);
EXPORT_SYMBOL_GPL(ata_data_xfer_noirq);
EXPORT_SYMBOL_GPL(ata_std_qc_defer);
EXPORT_SYMBOL_GPL(ata_qc_prep);
EXPORT_SYMBOL_GPL(ata_dumb_qc_prep);
EXPORT_SYMBOL_GPL(ata_noop_qc_prep);
......
......@@ -749,6 +749,13 @@ static void ata_scsi_sdev_config(struct scsi_device *sdev)
{
sdev->use_10_for_rw = 1;
sdev->use_10_for_ms = 1;
/* Schedule policy is determined by ->qc_defer() callback and
* it needs to see every deferred qc. Set dev_blocked to 1 to
* prevent SCSI midlayer from automatically deferring
* requests.
*/
sdev->max_device_blocked = 1;
}
static void ata_scsi_dev_config(struct scsi_device *sdev,
......@@ -1415,37 +1422,6 @@ static void ata_scsi_qc_complete(struct ata_queued_cmd *qc)
ata_qc_free(qc);
}
/**
* ata_scmd_need_defer - Check whether we need to defer scmd
* @dev: ATA device to which the command is addressed
* @is_io: Is the command IO (and thus possibly NCQ)?
*
* NCQ and non-NCQ commands cannot run together. As upper layer
* only knows the queue depth, we are responsible for maintaining
* exclusion. This function checks whether a new command can be
* issued to @dev.
*
* LOCKING:
* spin_lock_irqsave(host lock)
*
* RETURNS:
* 1 if deferring is needed, 0 otherwise.
*/
static int ata_scmd_need_defer(struct ata_device *dev, int is_io)
{
struct ata_link *link = dev->link;
int is_ncq = is_io && ata_ncq_enabled(dev);
if (is_ncq) {
if (!ata_tag_valid(link->active_tag))
return 0;
} else {
if (!ata_tag_valid(link->active_tag) && !link->sactive)
return 0;
}
return 1;
}
/**
* ata_scsi_translate - Translate then issue SCSI command to ATA device
* @dev: ATA device to which the command is addressed
......@@ -1477,14 +1453,12 @@ static int ata_scsi_translate(struct ata_device *dev, struct scsi_cmnd *cmd,
void (*done)(struct scsi_cmnd *),
ata_xlat_func_t xlat_func)
{
struct ata_port *ap = dev->link->ap;
struct ata_queued_cmd *qc;
int is_io = xlat_func == ata_scsi_rw_xlat;
int rc;
VPRINTK("ENTER\n");
if (unlikely(ata_scmd_need_defer(dev, is_io)))
goto defer;
qc = ata_scsi_qc_new(dev, cmd, done);
if (!qc)
goto err_mem;
......@@ -1508,6 +1482,11 @@ static int ata_scsi_translate(struct ata_device *dev, struct scsi_cmnd *cmd,
if (xlat_func(qc))
goto early_finish;
if (ap->ops->qc_defer) {
if ((rc = ap->ops->qc_defer(qc)))
goto defer;
}
/* select device, send command to hardware */
ata_qc_issue(qc);
......@@ -1529,8 +1508,12 @@ err_mem:
return 0;
defer:
ata_qc_free(qc);
DPRINTK("EXIT - defer\n");
return SCSI_MLQUEUE_DEVICE_BUSY;
if (rc == ATA_DEFER_LINK)
return SCSI_MLQUEUE_DEVICE_BUSY;
else
return SCSI_MLQUEUE_HOST_BUSY;
}
/**
......@@ -3034,6 +3017,13 @@ int ata_scsi_add_hosts(struct ata_host *host, struct scsi_host_template *sht)
shost->max_channel = 1;
shost->max_cmd_len = 16;
/* Schedule policy is determined by ->qc_defer()
* callback and it needs to see every deferred qc.
* Set host_blocked to 1 to prevent SCSI midlayer from
* automatically deferring requests.
*/
shost->max_host_blocked = 1;
rc = scsi_add_host(ap->scsi_host, ap->host->dev);
if (rc)
goto err_add;
......
......@@ -423,6 +423,7 @@ static const struct ata_port_operations nv_adma_ops = {
.bmdma_start = ata_bmdma_start,
.bmdma_stop = ata_bmdma_stop,
.bmdma_status = ata_bmdma_status,
.qc_defer = ata_std_qc_defer,
.qc_prep = nv_adma_qc_prep,
.qc_issue = nv_adma_qc_issue,
.freeze = nv_adma_freeze,
......
......@@ -393,6 +393,7 @@ static const struct ata_port_operations sil24_ops = {
.tf_read = sil24_tf_read,
.qc_defer = ata_std_qc_defer,
.qc_prep = sil24_qc_prep,
.qc_issue = sil24_qc_issue,
......
......@@ -272,6 +272,10 @@ enum {
/* ering size */
ATA_ERING_SIZE = 32,
/* return values for ->qc_defer */
ATA_DEFER_LINK = 1,
ATA_DEFER_PORT = 2,
/* desc_len for ata_eh_info and context */
ATA_EH_DESC_LEN = 80,
......@@ -639,6 +643,7 @@ struct ata_port_operations {
void (*data_xfer) (struct ata_device *, unsigned char *, unsigned int, int);
int (*qc_defer) (struct ata_queued_cmd *qc);
void (*qc_prep) (struct ata_queued_cmd *qc);
unsigned int (*qc_issue) (struct ata_queued_cmd *qc);
......@@ -824,6 +829,7 @@ extern void ata_data_xfer(struct ata_device *adev, unsigned char *buf,
unsigned int buflen, int write_data);
extern void ata_data_xfer_noirq(struct ata_device *adev, unsigned char *buf,
unsigned int buflen, int write_data);
extern int ata_std_qc_defer(struct ata_queued_cmd *qc);
extern void ata_dumb_qc_prep(struct ata_queued_cmd *qc);
extern void ata_qc_prep(struct ata_queued_cmd *qc);
extern void ata_noop_qc_prep(struct ata_queued_cmd *qc);
......
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