[SCSI] libata, libsas: introduce sched_eh and end_eh port ops

When managing shost->host_eh_scheduled libata assumes that there is a
1:1 shost-to-ata_port relationship.  libsas creates a 1:N relationship
so it needs to manage host_eh_scheduled cumulatively at the host level.
The sched_eh and end_eh port port ops allow libsas to track when domain
devices enter/leave the "eh-pending" state under ha->lock (previously
named ha->state_lock, but it is no longer just a lock for ha->state
changes).

Since host_eh_scheduled indicates eh without backing commands pinning
the device it can be deallocated at any time.  Move the taking of the
domain_device reference under the port_lock to guarantee that the
ata_port stays around for the duration of eh.

Reviewed-by: Jacek Danecki <jacek.danecki@intel.com>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

2 files changed, 50 insertions, 11 deletions

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index cece3a4..3fe1202 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -80,6 +80,8 @@ const struct ata_port_operations ata_base_port_ops = {
 	.prereset		= ata_std_prereset,
 	.postreset		= ata_std_postreset,
 	.error_handler		= ata_std_error_handler,
+	.sched_eh		= ata_std_sched_eh,
+	.end_eh			= ata_std_end_eh,
 };
 
 const struct ata_port_operations sata_port_ops = {
@@ -6642,6 +6644,8 @@ struct ata_port_operations ata_dummy_port_ops = {
 	.qc_prep		= ata_noop_qc_prep,
 	.qc_issue		= ata_dummy_qc_issue,
 	.error_handler		= ata_dummy_error_handler,
+	.sched_eh		= ata_std_sched_eh,
+	.end_eh			= ata_std_end_eh,
 };
 
 const struct ata_port_info ata_dummy_port_info = {
diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 6d53cf9..77fc806 100644
--- a/drivers/ata/libata-eh.c
+++ b/drivers/ata/libata-eh.c
@@ -793,12 +793,12 @@ void ata_scsi_port_error_handler(struct Scsi_Host *host, struct ata_port *ap)
 		ata_for_each_link(link, ap, HOST_FIRST)
 			memset(&link->eh_info, 0, sizeof(link->eh_info));
 
-		/* Clear host_eh_scheduled while holding ap->lock such
-		 * that if exception occurs after this point but
-		 * before EH completion, SCSI midlayer will
+		/* end eh (clear host_eh_scheduled) while holding
+		 * ap->lock such that if exception occurs after this
+		 * point but before EH completion, SCSI midlayer will
 		 * re-initiate EH.
 		 */
-		host->host_eh_scheduled = 0;
+		ap->ops->end_eh(ap);
 
 		spin_unlock_irqrestore(ap->lock, flags);
 		ata_eh_release(ap);
@@ -986,16 +986,13 @@ void ata_qc_schedule_eh(struct ata_queued_cmd *qc)
 }
 
 /**
- *	ata_port_schedule_eh - schedule error handling without a qc
- *	@ap: ATA port to schedule EH for
- *
- *	Schedule error handling for @ap.  EH will kick in as soon as
- *	all commands are drained.
+ * ata_std_sched_eh - non-libsas ata_ports issue eh with this common routine
+ * @ap: ATA port to schedule EH for
  *
- *	LOCKING:
+ *	LOCKING: inherited from ata_port_schedule_eh
  *	spin_lock_irqsave(host lock)
  */
-void ata_port_schedule_eh(struct ata_port *ap)
+void ata_std_sched_eh(struct ata_port *ap)
 {
 	WARN_ON(!ap->ops->error_handler);
 
@@ -1007,6 +1004,44 @@ void ata_port_schedule_eh(struct ata_port *ap)
 
 	DPRINTK("port EH scheduled\n");
 }
+EXPORT_SYMBOL_GPL(ata_std_sched_eh);
+
+/**
+ * ata_std_end_eh - non-libsas ata_ports complete eh with this common routine
+ * @ap: ATA port to end EH for
+ *
+ * In the libata object model there is a 1:1 mapping of ata_port to
+ * shost, so host fields can be directly manipulated under ap->lock, in
+ * the libsas case we need to hold a lock at the ha->level to coordinate
+ * these events.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+void ata_std_end_eh(struct ata_port *ap)
+{
+	struct Scsi_Host *host = ap->scsi_host;
+
+	host->host_eh_scheduled = 0;
+}
+EXPORT_SYMBOL(ata_std_end_eh);
+
+
+/**
+ *	ata_port_schedule_eh - schedule error handling without a qc
+ *	@ap: ATA port to schedule EH for
+ *
+ *	Schedule error handling for @ap.  EH will kick in as soon as
+ *	all commands are drained.
+ *
+ *	LOCKING:
+ *	spin_lock_irqsave(host lock)
+ */
+void ata_port_schedule_eh(struct ata_port *ap)
+{
+	/* see: ata_std_sched_eh, unless you know better */
+	ap->ops->sched_eh(ap);
+}
 
 static int ata_do_link_abort(struct ata_port *ap, struct ata_link *link)
 {