[SCSI] scsi_dh: Implement common device table handling

Instead of having each and every driver implement its own
device table scanning code we should rather implement a common
routine and scan the device tables there.
This allows us also to implement a general notifier chain
callback for all device handler instead for one per handler.

[sekharan: Fix rejections caused by conflicting bug fix]
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 170 insertions, 32 deletions

diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c
index ab6c21cd9689..3f798171ed69 100644
--- a/drivers/scsi/device_handler/scsi_dh.c
+++ b/drivers/scsi/device_handler/scsi_dh.c
@@ -33,7 +33,7 @@ static struct scsi_device_handler *get_device_handler(const char *name)
 
         spin_lock(&list_lock);
         list_for_each_entry(tmp, &scsi_dh_list, list) {
-                if (!strcmp(tmp->name, name)) {
+                if (!strncmp(tmp->name, name, strlen(tmp->name))) {
                         found = tmp;
                         break;
                 }
@@ -42,51 +42,173 @@ static struct scsi_device_handler *get_device_handler(const char *name)
         return found;
 }
 
-static int scsi_dh_notifier_add(struct device *dev, void *data)
+static int device_handler_match(struct scsi_device_handler *tmp,
+                                struct scsi_device *sdev)
 {
-        struct scsi_device_handler *scsi_dh = data;
+        int i;
+
+        for(i = 0; tmp->devlist[i].vendor; i++) {
+                if (!strncmp(sdev->vendor, tmp->devlist[i].vendor,
+                             strlen(tmp->devlist[i].vendor)) &&
+                    !strncmp(sdev->model, tmp->devlist[i].model,
+                             strlen(tmp->devlist[i].model))) {
+                        return 1;
+                }
+        }
 
-        scsi_dh->nb.notifier_call(&scsi_dh->nb, BUS_NOTIFY_ADD_DEVICE, dev);
         return 0;
 }
 
 /*
- * scsi_register_device_handler - register a device handler personality
- *      module.
- * @scsi_dh - device handler to be registered.
+ * scsi_dh_handler_attach - Attach a device handler to a device
+ * @sdev - SCSI device the device handler should attach to
+ * @scsi_dh - The device handler to attach
+ */
+static int scsi_dh_handler_attach(struct scsi_device *sdev,
+                                  struct scsi_device_handler *scsi_dh)
+{
+        int err = 0;
+
+        if (sdev->scsi_dh_data) {
+                if (sdev->scsi_dh_data->scsi_dh != scsi_dh)
+                        err = -EBUSY;
+        } else if (scsi_dh->attach)
+                err = scsi_dh->attach(sdev);
+
+        return err;
+}
+
+/*
+ * scsi_dh_handler_detach - Detach a device handler from a device
+ * @sdev - SCSI device the device handler should be detached from
+ * @scsi_dh - Device handler to be detached
  *
- * Returns 0 on success, -EBUSY if handler already registered.
+ * Detach from a device handler. If a device handler is specified,
+ * only detach if the currently attached handler is equal to it.
  */
-int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
+static void scsi_dh_handler_detach(struct scsi_device *sdev,
+                                   struct scsi_device_handler *scsi_dh)
 {
-        int ret = -EBUSY;
-        struct scsi_device_handler *tmp;
+        if (!sdev->scsi_dh_data)
+                return;
 
-        tmp = get_device_handler(scsi_dh->name);
-        if (tmp)
-                goto done;
+        if (scsi_dh && scsi_dh != sdev->scsi_dh_data->scsi_dh)
+                return;
 
-        ret = bus_register_notifier(&scsi_bus_type, &scsi_dh->nb);
+        if (!scsi_dh)
+                scsi_dh = sdev->scsi_dh_data->scsi_dh;
+
+        if (scsi_dh && scsi_dh->detach)
+                scsi_dh->detach(sdev);
+}
+
+/*
+ * scsi_dh_notifier - notifier chain callback
+ */
+static int scsi_dh_notifier(struct notifier_block *nb,
+                            unsigned long action, void *data)
+{
+        struct device *dev = data;
+        struct scsi_device *sdev;
+        int err = 0;
+        struct scsi_device_handler *tmp, *devinfo = NULL;
+
+        if (!scsi_is_sdev_device(dev))
+                return 0;
+
+        sdev = to_scsi_device(dev);
 
-        bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
         spin_lock(&list_lock);
-        list_add(&scsi_dh->list, &scsi_dh_list);
+        list_for_each_entry(tmp, &scsi_dh_list, list) {
+                if (device_handler_match(tmp, sdev)) {
+                        devinfo = tmp;
+                        break;
+                }
+        }
         spin_unlock(&list_lock);
 
-done:
-        return ret;
+        if (!devinfo)
+                goto out;
+
+        if (action == BUS_NOTIFY_ADD_DEVICE) {
+                err = scsi_dh_handler_attach(sdev, devinfo);
+        } else if (action == BUS_NOTIFY_DEL_DEVICE) {
+                scsi_dh_handler_detach(sdev, NULL);
+        }
+out:
+        return err;
 }
-EXPORT_SYMBOL_GPL(scsi_register_device_handler);
 
+/*
+ * scsi_dh_notifier_add - Callback for scsi_register_device_handler
+ */
+static int scsi_dh_notifier_add(struct device *dev, void *data)
+{
+        struct scsi_device_handler *scsi_dh = data;
+        struct scsi_device *sdev;
+
+        if (!scsi_is_sdev_device(dev))
+                return 0;
+
+        if (!get_device(dev))
+                return 0;
+
+        sdev = to_scsi_device(dev);
+
+        if (device_handler_match(scsi_dh, sdev))
+                scsi_dh_handler_attach(sdev, scsi_dh);
+
+        put_device(dev);
+
+        return 0;
+}
+
+/*
+ * scsi_dh_notifier_remove - Callback for scsi_unregister_device_handler
+ */
 static int scsi_dh_notifier_remove(struct device *dev, void *data)
 {
         struct scsi_device_handler *scsi_dh = data;
+        struct scsi_device *sdev;
+
+        if (!scsi_is_sdev_device(dev))
+                return 0;
+
+        if (!get_device(dev))
+                return 0;
+
+        sdev = to_scsi_device(dev);
+
+        scsi_dh_handler_detach(sdev, scsi_dh);
+
+        put_device(dev);
 
-        scsi_dh->nb.notifier_call(&scsi_dh->nb, BUS_NOTIFY_DEL_DEVICE, dev);
         return 0;
 }
 
 /*
+ * scsi_register_device_handler - register a device handler personality
+ *      module.
+ * @scsi_dh - device handler to be registered.
+ *
+ * Returns 0 on success, -EBUSY if handler already registered.
+ */
+int scsi_register_device_handler(struct scsi_device_handler *scsi_dh)
+{
+        if (get_device_handler(scsi_dh->name))
+                return -EBUSY;
+
+        spin_lock(&list_lock);
+        list_add(&scsi_dh->list, &scsi_dh_list);
+        spin_unlock(&list_lock);
+        bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh, scsi_dh_notifier_add);
+        printk(KERN_INFO "%s: device handler registered\n", scsi_dh->name);
+
+        return SCSI_DH_OK;
+}
+EXPORT_SYMBOL_GPL(scsi_register_device_handler);
+
+/*
  * scsi_unregister_device_handler - register a device handler personality
  *      module.
  * @scsi_dh - device handler to be unregistered.
@@ -95,23 +217,18 @@ static int scsi_dh_notifier_remove(struct device *dev, void *data)
  */
 int scsi_unregister_device_handler(struct scsi_device_handler *scsi_dh)
 {
-        int ret = -ENODEV;
-        struct scsi_device_handler *tmp;
-
-        tmp = get_device_handler(scsi_dh->name);
-        if (!tmp)
-                goto done;
-
-        ret = bus_unregister_notifier(&scsi_bus_type, &scsi_dh->nb);
+        if (!get_device_handler(scsi_dh->name))
+                return -ENODEV;
 
         bus_for_each_dev(&scsi_bus_type, NULL, scsi_dh,
-                                        scsi_dh_notifier_remove);
+                         scsi_dh_notifier_remove);
+
         spin_lock(&list_lock);
         list_del(&scsi_dh->list);
         spin_unlock(&list_lock);
+        printk(KERN_INFO "%s: device handler unregistered\n", scsi_dh->name);
 
-done:
-        return ret;
+        return SCSI_DH_OK;
 }
 EXPORT_SYMBOL_GPL(scsi_unregister_device_handler);
 
@@ -157,6 +274,27 @@ int scsi_dh_handler_exist(const char *name)
 }
 EXPORT_SYMBOL_GPL(scsi_dh_handler_exist);
 
+static struct notifier_block scsi_dh_nb = {
+        .notifier_call = scsi_dh_notifier
+};
+
+static int __init scsi_dh_init(void)
+{
+        int r;
+
+        r = bus_register_notifier(&scsi_bus_type, &scsi_dh_nb);
+
+        return r;
+}
+
+static void __exit scsi_dh_exit(void)
+{
+        bus_unregister_notifier(&scsi_bus_type, &scsi_dh_nb);
+}
+
+module_init(scsi_dh_init);
+module_exit(scsi_dh_exit);
+
 MODULE_DESCRIPTION("SCSI device handler");
 MODULE_AUTHOR("Chandra Seetharaman <sekharan@us.ibm.com>");
 MODULE_LICENSE("GPL");