[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>

2 files changed, 51 insertions, 25 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);
diff --git a/drivers/scsi/device_handler/scsi_dh_alua.c b/drivers/scsi/device_handler/scsi_dh_alua.c
index 432677889eae..80c5cf327b84 100644
--- a/drivers/scsi/device_handler/scsi_dh_alua.c
+++ b/drivers/scsi/device_handler/scsi_dh_alua.c
@@ -677,23 +677,10 @@ static int alua_prep_fn(struct scsi_device *sdev, struct request *req)
 
 }
 
-static const struct scsi_dh_devlist alua_dev_list[] = {
-        {"HP", "MSA VOLUME" },
-        {"HP", "HSV101" },
-        {"HP", "HSV111" },
-        {"HP", "HSV200" },
-        {"HP", "HSV210" },
-        {"HP", "HSV300" },
-        {"IBM", "2107900" },
-        {"IBM", "2145" },
-        {"Pillar", "Axiom" },
-        {"Intel", "Multi-Flex"},
-        {"NETAPP", "LUN"},
-        {"NETAPP", "LUN C-Mode"},
-        {"AIX", "NVDISK"},
-        {"Promise", "VTrak"},
-        {NULL, NULL}
-};
+static bool alua_match(struct scsi_device *sdev)
+{
+        return (scsi_device_tpgs(sdev) != 0);
+}
 
 static int alua_bus_attach(struct scsi_device *sdev);
 static void alua_bus_detach(struct scsi_device *sdev);
@@ -701,12 +688,12 @@ static void alua_bus_detach(struct scsi_device *sdev);
 static struct scsi_device_handler alua_dh = {
         .name = ALUA_DH_NAME,
         .module = THIS_MODULE,
-        .devlist = alua_dev_list,
         .attach = alua_bus_attach,
         .detach = alua_bus_detach,
         .prep_fn = alua_prep_fn,
         .check_sense = alua_check_sense,
         .activate = alua_activate,
+        .match = alua_match,
 };
 
 /*