1 files changed, 33 insertions, 16 deletions

diff --git a/include/linux/genl_magic_func.h b/include/linux/genl_magic_func.h
index c8c67239f616..e458282a3728 100644
--- a/include/linux/genl_magic_func.h
+++ b/include/linux/genl_magic_func.h
@@ -190,11 +190,12 @@ static struct nlattr *nested_attr_tb[128];
 
 #undef GENL_struct
 #define GENL_struct(tag_name, tag_number, s_name, s_fields)             \
-        /* static, potentially unused */                                \
-int s_name ## _from_attrs(struct s_name *s, struct nlattr *tb[])        \
+/* *_from_attrs functions are static, but potentially unused */         \
+static int __ ## s_name ## _from_attrs(struct s_name *s,                \
+                struct genl_info *info, bool exclude_invariants)        \
 {                                                                       \
         const int maxtype = ARRAY_SIZE(s_name ## _nl_policy)-1;         \
-        struct nlattr *tla = tb[tag_number];                            \
+        struct nlattr *tla = info->attrs[tag_number];                   \
         struct nlattr **ntb = nested_attr_tb;                           \
         struct nlattr *nla;                                             \
         int err;                                                        \
@@ -211,33 +212,49 @@ int s_name ## _from_attrs(struct s_name *s, struct nlattr *tb[])	\
                                                                         \
         s_fields                                                        \
         return 0;                                                       \
-}
+}                                       __attribute__((unused))         \
+static int s_name ## _from_attrs(struct s_name *s,                      \
+                                                struct genl_info *info) \
+{                                                                       \
+        return __ ## s_name ## _from_attrs(s, info, false);             \
+}                                       __attribute__((unused))         \
+static int s_name ## _from_attrs_for_change(struct s_name *s,           \
+                                                struct genl_info *info) \
+{                                                                       \
+        return __ ## s_name ## _from_attrs(s, info, true);              \
+}                                       __attribute__((unused))         \
 
-#undef __field
-#define __field(attr_nr, attr_flag, name, nla_type, type, __get, __put) \
+#define __assign(attr_nr, attr_flag, name, nla_type, type, assignment...)       \
                 nla = ntb[__nla_type(attr_nr)];                         \
                 if (nla) {                                              \
-                        if (s)                                          \
-                                s->name = __get(nla);                   \
-                        DPRINT_FIELD("<<", nla_type, name, s, nla);     \
+                        if (exclude_invariants && ((attr_flag) & GENLA_F_INVARIANT)) {          \
+                                pr_info("<< must not change invariant attr: %s\n", #name);      \
+                                return -EEXIST;                         \
+                        }                                               \
+                        assignment;                                     \
+                } else if (exclude_invariants && ((attr_flag) & GENLA_F_INVARIANT)) {           \
+                        /* attribute missing from payload, */           \
+                        /* which was expected */                        \
                 } else if ((attr_flag) & GENLA_F_REQUIRED) {            \
                         pr_info("<< missing attr: %s\n", #name);        \
                         return -ENOMSG;                                 \
                 }
 
+#undef __field
+#define __field(attr_nr, attr_flag, name, nla_type, type, __get, __put) \
+        __assign(attr_nr, attr_flag, name, nla_type, type,              \
+                        if (s)                                          \
+                                s->name = __get(nla);                   \
+                        DPRINT_FIELD("<<", nla_type, name, s, nla))
+
 /* validate_nla() already checked nla_len <= maxlen appropriately. */
 #undef __array
 #define __array(attr_nr, attr_flag, name, nla_type, type, maxlen, __get, __put) \
-                nla = ntb[__nla_type(attr_nr)];                         \
-                if (nla) {                                              \
+        __assign(attr_nr, attr_flag, name, nla_type, type,              \
                         if (s)                                          \
                                 s->name ## _len =                       \
                                         __get(s->name, nla, maxlen);    \
-                        DPRINT_ARRAY("<<", nla_type, name, s, nla);     \
-                } else if ((attr_flag) & GENLA_F_REQUIRED) {            \
-                        pr_info("<< missing attr: %s\n", #name);        \
-                        return -ENOMSG;                                 \
-                }                                                       \
+                        DPRINT_ARRAY("<<", nla_type, name, s, nla))
 
 #include GENL_MAGIC_INCLUDE_FILE