libata-pmp-prep: implement qc_defer helpers
Implement ap->nr_active_links (the number of links with active qcs),
ap->excl_link (pointer to link which can be used by ->qc_defer and is
cleared when a qc with ATA_QCFLAG_CLEAR_EXCL completes), and
ata_link_active().
These can be used by ->qc_defer() to implement proper command
exclusion. This set of helpers seem enough for both sil24 (ATAPI
exclusion needed) and cmd-switching PMP.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index b666f51..376dbd8 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1390,6 +1390,7 @@
struct ata_queued_cmd *qc;
unsigned int tag, preempted_tag;
u32 preempted_sactive, preempted_qc_active;
+ int preempted_nr_active_links;
DECLARE_COMPLETION_ONSTACK(wait);
unsigned long flags;
unsigned int err_mask;
@@ -1428,9 +1429,11 @@
preempted_tag = link->active_tag;
preempted_sactive = link->sactive;
preempted_qc_active = ap->qc_active;
+ 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;
/* prepare & issue qc */
qc->tf = *tf;
@@ -1509,6 +1512,7 @@
link->active_tag = preempted_tag;
link->sactive = preempted_sactive;
ap->qc_active = preempted_qc_active;
+ ap->nr_active_links = preempted_nr_active_links;
/* XXX - Some LLDDs (sata_mv) disable port on command failure.
* Until those drivers are fixed, we detect the condition
@@ -5408,10 +5412,19 @@
ata_sg_clean(qc);
/* command should be marked inactive atomically with qc completion */
- if (qc->tf.protocol == ATA_PROT_NCQ)
+ if (qc->tf.protocol == ATA_PROT_NCQ) {
link->sactive &= ~(1 << qc->tag);
- else
+ if (!link->sactive)
+ ap->nr_active_links--;
+ } else {
link->active_tag = ATA_TAG_POISON;
+ ap->nr_active_links--;
+ }
+
+ /* clear exclusive status */
+ if (unlikely(qc->flags & ATA_QCFLAG_CLEAR_EXCL &&
+ ap->excl_link == link))
+ ap->excl_link = NULL;
/* atapi: mark qc as inactive to prevent the interrupt handler
* from completing the command twice later, before the error handler
@@ -5590,9 +5603,14 @@
if (qc->tf.protocol == ATA_PROT_NCQ) {
WARN_ON(link->sactive & (1 << qc->tag));
+
+ if (!link->sactive)
+ ap->nr_active_links++;
link->sactive |= 1 << qc->tag;
} else {
WARN_ON(link->sactive);
+
+ ap->nr_active_links++;
link->active_tag = qc->tag;
}