From 31cc23b34913bc173680bdc87af79e551bf8cc0d Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Sun, 23 Sep 2007 13:14:12 +0900 Subject: [PATCH] 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: Tejun Heo Signed-off-by: Jeff Garzik --- drivers/ata/ahci.c | 2 ++ drivers/ata/libata-core.c | 31 ++++++++++++++++++++ drivers/ata/libata-scsi.c | 62 ++++++++++++++++----------------------- drivers/ata/sata_nv.c | 1 + drivers/ata/sata_sil24.c | 1 + include/linux/libata.h | 6 ++++ 6 files changed, 67 insertions(+), 36 deletions(-) diff --git a/drivers/ata/ahci.c b/drivers/ata/ahci.c index 0a6b694f0d3a..cf3404467ceb 100644 --- a/drivers/ata/ahci.c +++ b/drivers/ata/ahci.c @@ -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, diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c index 9467c2f60192..b666f51da7ed 100644 --- a/drivers/ata/libata-core.c +++ b/drivers/ata/libata-core.c @@ -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); diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c index dc274001ddd9..8ca2caeed017 100644 --- a/drivers/ata/libata-scsi.c +++ b/drivers/ata/libata-scsi.c @@ -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; diff --git a/drivers/ata/sata_nv.c b/drivers/ata/sata_nv.c index b860f99fc288..40557fe2ffdf 100644 --- a/drivers/ata/sata_nv.c +++ b/drivers/ata/sata_nv.c @@ -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, diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c index d9c010ab2280..9acfce43bde4 100644 --- a/drivers/ata/sata_sil24.c +++ b/drivers/ata/sata_sil24.c @@ -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, diff --git a/include/linux/libata.h b/include/linux/libata.h index c3820f105ffa..b0d4ca0d27b4 100644 --- a/include/linux/libata.h +++ b/include/linux/libata.h @@ -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); -- 2.20.1