[SCSI] scsi_dh: Implement match callback function

Some device handler types are not tied to the vendor/model
but rather to a specific capability. Eg ALUA is supported
if the 'TPGS' setting in the standard inquiry is set.
This patch implements a 'match' callback for device handler
which supersedes the original vendor/model lookup and
implements the callback for the ALUA handler.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

1 files changed, 46 insertions, 7 deletions

diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c
index fccd0f6cfc90..3ac71cf6b7f0 100644
--- a/drivers/scsi/device_handler/scsi_dh.c
+++ b/drivers/scsi/device_handler/scsi_dh.c
@@ -60,6 +60,46 @@ static struct scsi_device_handler *get_device_handler_by_idx(int idx)
 }
 
 /*
+ * device_handler_match_function - Match a device handler to a device
+ * @sdev - SCSI device to be tested
+ *
+ * Tests @sdev against the match function of all registered device_handler.
+ * Returns the found device handler or NULL if not found.
+ */
+static struct scsi_device_handler *
+device_handler_match_function(struct scsi_device *sdev)
+{
+	struct scsi_device_handler *tmp_dh, *found_dh = NULL;
+
+	spin_lock(&list_lock);
+	list_for_each_entry(tmp_dh, &scsi_dh_list, list) {
+		if (tmp_dh->match && tmp_dh->match(sdev)) {
+			found_dh = tmp_dh;
+			break;
+		}
+	}
+	spin_unlock(&list_lock);
+	return found_dh;
+}
+
+/*
+ * device_handler_match_devlist - Match a device handler to a device
+ * @sdev - SCSI device to be tested
+ *
+ * Tests @sdev against all device_handler registered in the devlist.
+ * Returns the found device handler or NULL if not found.
+ */
+static struct scsi_device_handler *
+device_handler_match_devlist(struct scsi_device *sdev)
+{
+	int idx;
+
+	idx = scsi_get_device_flags_keyed(sdev, sdev->vendor, sdev->model,
+					  SCSI_DEVINFO_DH);
+	return get_device_handler_by_idx(idx);
+}
+
+/*
  * device_handler_match - Attach a device handler to a device
  * @scsi_dh - The device handler to match against or NULL
  * @sdev - SCSI device to be tested against @scsi_dh
@@ -72,12 +112,11 @@ static struct scsi_device_handler *
 device_handler_match(struct scsi_device_handler *scsi_dh,
 		     struct scsi_device *sdev)
 {
-	struct scsi_device_handler *found_dh = NULL;
-	int idx;
+	struct scsi_device_handler *found_dh;
 
-	idx = scsi_get_device_flags_keyed(sdev, sdev->vendor, sdev->model,
-					  SCSI_DEVINFO_DH);
-	found_dh = get_device_handler_by_idx(idx);
+	found_dh = device_handler_match_function(sdev);
+	if (!found_dh)
+		found_dh = device_handler_match_devlist(sdev);
 
 	if (scsi_dh && found_dh != scsi_dh)
 		found_dh = NULL;
@@ -327,7 +366,7 @@ int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
 	list_add(&scsi_dh->list, &scsi_dh_list);
 	spin_unlock(&list_lock);
 
-	for (i = 0; scsi_dh->devlist[i].vendor; i++) {
+	for (i = 0; scsi_dh->devlist && scsi_dh->devlist[i].vendor; i++) {
 		scsi_dev_info_list_add_keyed(0,
 					scsi_dh->devlist[i].vendor,
 					scsi_dh->devlist[i].model,
@@ -360,7 +399,7 @@ int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
 	bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
 			 scsi_dh_notifier_remove);
 
-	for (i = 0; scsi_dh->devlist[i].vendor; i++) {
+	for (i = 0; scsi_dh->devlist && scsi_dh->devlist[i].vendor; i++) {
 		scsi_dev_info_list_del_keyed(scsi_dh->devlist[i].vendor,
 					     scsi_dh->devlist[i].model,
 					     SCSI_DEVINFO_DH);