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-eh.c b/drivers/ata/libata-eh.c
index 1d3b0dc..5244723 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -451,6 +451,7 @@
ap->pflags |= ATA_PFLAG_EH_IN_PROGRESS;
ap->pflags &= ~ATA_PFLAG_EH_PENDING;
+ ap->excl_link = NULL; /* don't maintain exclusion over EH */
spin_unlock_irqrestore(ap->lock, flags);
@@ -2474,6 +2475,10 @@
}
}
}
+
+ /* make sure nr_active_links is zero after EH */
+ WARN_ON(ap->nr_active_links);
+ ap->nr_active_links = 0;
}
/**