amd64_edac: make driver loading more robust

Currently, the module does not initialize fully when the DIMMs aren't
ECC but remains still loaded. Propagate the error when no instance of
the driver is properly initialized and prevent further loading.

Reorganize and polish error handling in amd64_edac_init() while at it.
Signed-off-by: Borislav Petkov <borislav.petkov@amd.com>

drivers/edac/amd64_edac.c

@@ -3014,25 +3014,29 @@ static void amd64_setup_pci_device(void)
 static int __init amd64_edac_init(void)
 {
 	int nb, err = -ENODEV;
+	bool load_ok = false;
 
 	edac_printk(KERN_INFO, EDAC_MOD_STR, EDAC_AMD64_VERSION "\n");
 
 	opstate_init();
 
 	if (cache_k8_northbridges() < 0)
-		return err;
+		goto err_ret;
 
 	msrs = msrs_alloc();
+	if (!msrs)
+		goto err_ret;
 
 	err = pci_register_driver(&amd64_pci_driver);
 	if (err)
-		return err;
+		goto err_pci;
 
 	/*
 	 * At this point, the array 'pvt_lookup[]' contains pointers to alloc'd
 	 * amd64_pvt structs. These will be used in the 2nd stage init function
 	 * to finish initialization of the MC instances.
 	 */
+	err = -ENODEV;
 	for (nb = 0; nb < num_k8_northbridges; nb++) {
 		if (!pvt_lookup[nb])
 			continue;
@@ -3040,16 +3044,21 @@ static int __init amd64_edac_init(void)
 		err = amd64_init_2nd_stage(pvt_lookup[nb]);
 		if (err)
 			goto err_2nd_stage;
+
+		load_ok = true;
 	}
 
+	if (load_ok) {
 		amd64_setup_pci_device();
-
 		return 0;
+	}
 
 err_2nd_stage:
-	debugf0("2nd stage failed\n");
 	pci_unregister_driver(&amd64_pci_driver);
-
+err_pci:
+	msrs_free(msrs);
+	msrs = NULL;
+err_ret:
 	return err;
 }