powerpc/fadump: Return error when fadump registration fails

 - log an error message when registration fails and no error code listed
   in the switch is returned
 - translate the hv error code to posix error code and return it from
   fw_register
 - return the posix error code from fw_register to the process writing
   to sysfs
 - return EEXIST on re-registration
 - return success on deregistration when fadump is not registered
 - return ENODEV when no memory is reserved for fadump
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Tested-by: Hari Bathini <hbathini@linux.vnet.ibm.com>
[mpe: Use pr_err() to shrink the error print]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/kernel/fadump.c

@@ -377,9 +377,9 @@ static int __init early_fadump_param(char *p)
 }
 early_param("fadump", early_fadump_param);
 
-static void register_fw_dump(struct fadump_mem_struct *fdm)
+static int register_fw_dump(struct fadump_mem_struct *fdm)
 {
-	int rc;
+	int rc, err;
 	unsigned int wait_time;
 
 	pr_debug("Registering for firmware-assisted kernel dump...\n");
@@ -396,7 +396,11 @@ static void register_fw_dump(struct fadump_mem_struct *fdm)
 
 	} while (wait_time);
 
+	err = -EIO;
 	switch (rc) {
+	default:
+		pr_err("Failed to register. Unknown Error(%d).\n", rc);
+		break;
 	case -1:
 		printk(KERN_ERR "Failed to register firmware-assisted kernel"
 			" dump. Hardware Error(%d).\n", rc);
@@ -404,18 +408,22 @@ static void register_fw_dump(struct fadump_mem_struct *fdm)
 	case -3:
 		printk(KERN_ERR "Failed to register firmware-assisted kernel"
 			" dump. Parameter Error(%d).\n", rc);
+		err = -EINVAL;
 		break;
 	case -9:
 		printk(KERN_ERR "firmware-assisted kernel dump is already "
 			" registered.");
 		fw_dump.dump_registered = 1;
+		err = -EEXIST;
 		break;
 	case 0:
 		printk(KERN_INFO "firmware-assisted kernel dump registration"
 			" is successful\n");
 		fw_dump.dump_registered = 1;
+		err = 0;
 		break;
 	}
+	return err;
 }
 
 void crash_fadump(struct pt_regs *regs, const char *str)
@@ -956,7 +964,7 @@ static unsigned long init_fadump_header(unsigned long addr)
 	return addr;
 }
 
-static void register_fadump(void)
+static int register_fadump(void)
 {
 	unsigned long addr;
 	void *vaddr;
@@ -966,7 +974,7 @@ static void register_fadump(void)
 	 * assisted dump.
 	 */
 	if (!fw_dump.reserve_dump_area_size)
-		return;
+		return -ENODEV;
 
 	fadump_setup_crash_memory_ranges();
 
@@ -979,7 +987,7 @@ static void register_fadump(void)
 	fadump_create_elfcore_headers(vaddr);
 
 	/* register the future kernel dump with firmware. */
-	register_fw_dump(&fdm);
+	return register_fw_dump(&fdm);
 }
 
 static int fadump_unregister_dump(struct fadump_mem_struct *fdm)
@@ -1161,7 +1169,6 @@ static ssize_t fadump_register_store(struct kobject *kobj,
 	switch (buf[0]) {
 	case '0':
 		if (fw_dump.dump_registered == 0) {
-			ret = -EINVAL;
 			goto unlock_out;
 		}
 		/* Un-register Firmware-assisted dump */
@@ -1169,11 +1176,11 @@ static ssize_t fadump_register_store(struct kobject *kobj,
 		break;
 	case '1':
 		if (fw_dump.dump_registered == 1) {
-			ret = -EINVAL;
+			ret = -EEXIST;
 			goto unlock_out;
 		}
 		/* Register Firmware-assisted dump */
-		register_fadump();
+		ret = register_fadump();
 		break;
 	default:
 		ret = -EINVAL;