[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>

1 files changed, 46 insertions, 11 deletions

diff --git a/drivers/ata/libata-eh.c b/drivers/ata/libata-eh.c
index 6d53cf9b3b6e..77fc80640e26 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)
 {