[PATCH] fix reading string module parameters in sysfs

Reading the contents of a module_param_string through sysfs currently
oopses because the param_get_charp() function cannot operate on a
kparam_string struct.  This introduces the required param_get_string.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/moduleparam.h

@@ -73,7 +73,7 @@ struct kparam_array
 #define module_param_string(name, string, len, perm)			\
 	static struct kparam_string __param_string_##name		\
 		= { len, string };					\
-	module_param_call(name, param_set_copystring, param_get_charp,	\
+	module_param_call(name, param_set_copystring, param_get_string,	\
 		   &__param_string_##name, perm)
 
 /* Called on module insert or kernel boot */
@@ -140,6 +140,7 @@ extern int param_array_set(const char *val, struct kernel_param *kp);
 extern int param_array_get(char *buffer, struct kernel_param *kp);
 
 extern int param_set_copystring(const char *val, struct kernel_param *kp);
+extern int param_get_string(char *buffer, struct kernel_param *kp);
 
 int param_array(const char *name,
 		const char *val,

kernel/params.c

@@ -339,6 +339,12 @@ int param_set_copystring(const char *val, struct kernel_param *kp)
 	return 0;
 }
 
+int param_get_string(char *buffer, struct kernel_param *kp)
+{
+	struct kparam_string *kps = kp->arg;
+	return strlcpy(buffer, kps->string, kps->maxlen);
+}
+
 EXPORT_SYMBOL(param_set_short);
 EXPORT_SYMBOL(param_get_short);
 EXPORT_SYMBOL(param_set_ushort);
@@ -360,3 +366,4 @@ EXPORT_SYMBOL(param_get_invbool);
 EXPORT_SYMBOL(param_array_set);
 EXPORT_SYMBOL(param_array_get);
 EXPORT_SYMBOL(param_set_copystring);
+EXPORT_SYMBOL(param_get_string);