kallsyms: Clean up modname and modbuildid initialization in kallsyms_lookup_buildid()

The @modname and @modbuildid optional return parameters are set only
when the symbol is in a module.

Always initialize them so that they do not need to be cleared when
the module is not in a module. It simplifies the logic and makes
the code even slightly more safe.

Note that bpf_address_lookup() function will get updated in a separate
patch.

Signed-off-by: Petr Mladek <[email protected]>

Author: pmladek

kernel/kallsyms.c

@@ -359,6 +359,14 @@ static int kallsyms_lookup_buildid(unsigned long addr,
 	 * or empty string.
 	 */
 	namebuf[0] = 0;
+	/*
+	 * Initialize the module-related return values. They are not set
+	 * when the symbol is in vmlinux or it is a bpf address.
+	 */
+	if (modname)
+		*modname = NULL;
+	if (modbuildid)
+		*modbuildid = NULL;
 
 	if (is_ksym_addr(addr)) {
 		unsigned long pos;
@@ -367,10 +375,6 @@ static int kallsyms_lookup_buildid(unsigned long addr,
 		/* Grab name */
 		kallsyms_expand_symbol(get_symbol_offset(pos),
 				       namebuf, KSYM_NAME_LEN);
-		if (modname)
-			*modname = NULL;
-		if (modbuildid)
-			*modbuildid = NULL;
 
 		return strlen(namebuf);
 	}