drbd: prepare the transition from connector to genetlink

This adds the new API header and helper files.

Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Lars Ellenberg <lars.ellenberg@linbit.com>

1 files changed, 260 insertions, 0 deletions

diff --git a/include/linux/genl_magic_struct.h b/include/linux/genl_magic_struct.h
new file mode 100644
index 000000000000..745ebfd6c7e5
--- /dev/null
+++ b/include/linux/genl_magic_struct.h
@@ -0,0 +1,260 @@
+#ifndef GENL_MAGIC_STRUCT_H
+#define GENL_MAGIC_STRUCT_H
+
+#ifndef GENL_MAGIC_FAMILY
+# error "you need to define GENL_MAGIC_FAMILY before inclusion"
+#endif
+
+#ifndef GENL_MAGIC_VERSION
+# error "you need to define GENL_MAGIC_VERSION before inclusion"
+#endif
+
+#ifndef GENL_MAGIC_INCLUDE_FILE
+# error "you need to define GENL_MAGIC_INCLUDE_FILE before inclusion"
+#endif
+
+#include <linux/genetlink.h>
+#include <linux/types.h>
+
+#define CONCAT__(a,b)   a ## b
+#define CONCAT_(a,b)    CONCAT__(a,b)
+
+extern int CONCAT_(GENL_MAGIC_FAMILY, _genl_register)(void);
+extern void CONCAT_(GENL_MAGIC_FAMILY, _genl_unregister)(void);
+
+/*
+ * Extension of genl attribute validation policies                      {{{2
+ */
+
+/**
+ * GENLA_F_FLAGS - policy type flags to ease compatible ABI evolvement
+ *
+ * @GENLA_F_REQUIRED: attribute has to be present, or message is considered invalid.
+ * Adding new REQUIRED attributes breaks ABI compatibility, so don't do that.
+ *
+ * @GENLA_F_MANDATORY: if present, receiver _must_ understand it.
+ * Without this, unknown attributes (> maxtype) are _silently_ ignored
+ * by validate_nla().
+ *
+ * To be used for API extensions, so older kernel can reject requests for not
+ * yet implemented features, if newer userland tries to use them even though
+ * the genl_family version clearly indicates they are not available.
+ *
+ * @GENLA_F_MAY_IGNORE: To clearly document the fact, for good measure.
+ * To be used for API extensions for things that have sane defaults,
+ * so newer userland can still talk to older kernel, knowing it will
+ * silently ignore these attributes if not yet known.
+ *
+ * NOTE: These flags overload
+ *   NLA_F_NESTED               (1 << 15)
+ *   NLA_F_NET_BYTEORDER        (1 << 14)
+ * from linux/netlink.h, which are not useful for validate_nla():
+ * NET_BYTEORDER is not used anywhere, and NESTED would be specified by setting
+ * .type = NLA_NESTED in the appropriate policy.
+ *
+ * See also: nla_type()
+ */
+enum {
+        GENLA_F_MAY_IGNORE      = 0,
+        GENLA_F_MANDATORY       = 1 << 14,
+        GENLA_F_REQUIRED        = 1 << 15,
+
+        /* This will not be present in the __u16 .nla_type, but can be
+         * triggered on in <struct>_to_skb, to exclude "sensitive"
+         * information from broadcasts, or on unpriviledged get requests.
+         * This is useful because genetlink multicast groups can be listened in
+         * on by anyone.  */
+        GENLA_F_SENSITIVE       = 1 << 16,
+};
+
+#define __nla_type(x)   ((__u16)((__u16)(x) & (__u16)NLA_TYPE_MASK))
+
+/*                                                                      }}}1
+ * MAGIC
+ * multi-include macro expansion magic starts here
+ */
+
+/* MAGIC helpers                                                        {{{2 */
+
+/* possible field types */
+#define __flg_field(attr_nr, attr_flag, name) \
+        __field(attr_nr, attr_flag, name, NLA_FLAG, char, \
+                        nla_get_flag, __nla_put_flag)
+#define __u8_field(attr_nr, attr_flag, name)    \
+        __field(attr_nr, attr_flag, name, NLA_U8, unsigned char, \
+                        nla_get_u8, NLA_PUT_U8)
+#define __u16_field(attr_nr, attr_flag, name)   \
+        __field(attr_nr, attr_flag, name, NLA_U16, __u16, \
+                        nla_get_u16, NLA_PUT_U16)
+#define __u32_field(attr_nr, attr_flag, name)   \
+        __field(attr_nr, attr_flag, name, NLA_U32, __u32, \
+                        nla_get_u32, NLA_PUT_U32)
+#define __u64_field(attr_nr, attr_flag, name)   \
+        __field(attr_nr, attr_flag, name, NLA_U64, __u64, \
+                        nla_get_u64, NLA_PUT_U64)
+#define __str_field(attr_nr, attr_flag, name, maxlen) \
+        __array(attr_nr, attr_flag, name, NLA_NUL_STRING, char, maxlen, \
+                        nla_strlcpy, NLA_PUT)
+#define __bin_field(attr_nr, attr_flag, name, maxlen) \
+        __array(attr_nr, attr_flag, name, NLA_BINARY, char, maxlen, \
+                        nla_memcpy, NLA_PUT)
+
+#define __nla_put_flag(skb, attrtype, value)            \
+        do {                                            \
+                if (value)                              \
+                        NLA_PUT_FLAG(skb, attrtype);    \
+        } while (0)
+
+#define GENL_op_init(args...)   args
+#define GENL_doit(handler)              \
+        .doit = handler,                \
+        .flags = GENL_ADMIN_PERM,
+#define GENL_dumpit(handler)            \
+        .dumpit = handler,              \
+        .flags = GENL_ADMIN_PERM,
+
+/*                                                                      }}}1
+ * Magic: define the enum symbols for genl_ops
+ * Magic: define the enum symbols for top level attributes
+ * Magic: define the enum symbols for nested attributes
+ *                                                                      {{{2
+ */
+
+#undef GENL_struct
+#define GENL_struct(tag_name, tag_number, s_name, s_fields)
+
+#undef GENL_mc_group
+#define GENL_mc_group(group)
+
+#undef GENL_notification
+#define GENL_notification(op_name, op_num, mcast_group, tla_list)       \
+        op_name = op_num,
+
+#undef GENL_op
+#define GENL_op(op_name, op_num, handler, tla_list)                     \
+        op_name = op_num,
+
+enum {
+#include GENL_MAGIC_INCLUDE_FILE
+};
+
+#undef GENL_notification
+#define GENL_notification(op_name, op_num, mcast_group, tla_list)
+
+#undef GENL_op
+#define GENL_op(op_name, op_num, handler, attr_list)
+
+#undef GENL_struct
+#define GENL_struct(tag_name, tag_number, s_name, s_fields) \
+                tag_name = tag_number,
+
+enum {
+#include GENL_MAGIC_INCLUDE_FILE
+};
+
+#undef GENL_struct
+#define GENL_struct(tag_name, tag_number, s_name, s_fields)     \
+enum {                                                          \
+        s_fields                                                \
+};
+
+#undef __field
+#define __field(attr_nr, attr_flag, name, nla_type, type, __get, __put) \
+        T_ ## name = (__u16)(attr_nr | attr_flag),
+
+#undef __array
+#define __array(attr_nr, attr_flag, name, nla_type, type, maxlen, __get, __put) \
+        T_ ## name = (__u16)(attr_nr | attr_flag),
+
+#include GENL_MAGIC_INCLUDE_FILE
+
+/*                                                                      }}}1
+ * Magic: compile time assert unique numbers for operations
+ * Magic: -"- unique numbers for top level attributes
+ * Magic: -"- unique numbers for nested attributes
+ *                                                                      {{{2
+ */
+
+#undef GENL_struct
+#define GENL_struct(tag_name, tag_number, s_name, s_fields)
+
+#undef GENL_op
+#define GENL_op(op_name, op_num, handler, attr_list)    \
+        case op_name:
+
+#undef GENL_notification
+#define GENL_notification(op_name, op_num, mcast_group, tla_list)       \
+        case op_name:
+
+static inline void ct_assert_unique_operations(void)
+{
+        switch (0) {
+#include GENL_MAGIC_INCLUDE_FILE
+                ;
+        }
+}
+
+#undef GENL_op
+#define GENL_op(op_name, op_num, handler, attr_list)
+
+#undef GENL_notification
+#define GENL_notification(op_name, op_num, mcast_group, tla_list)
+
+#undef GENL_struct
+#define GENL_struct(tag_name, tag_number, s_name, s_fields)             \
+                case tag_number:
+
+static inline void ct_assert_unique_top_level_attributes(void)
+{
+        switch (0) {
+#include GENL_MAGIC_INCLUDE_FILE
+                ;
+        }
+}
+
+#undef GENL_struct
+#define GENL_struct(tag_name, tag_number, s_name, s_fields)             \
+static inline void ct_assert_unique_ ## s_name ## _attributes(void)     \
+{                                                                       \
+        switch (0) {                                                    \
+                s_fields                                                \
+                        ;                                               \
+        }                                                               \
+}
+
+#undef __field
+#define __field(attr_nr, attr_flag, name, nla_type, type, __get, __put) \
+        case attr_nr:
+
+#undef __array
+#define __array(attr_nr, attr_flag, name, nla_type, type, maxlen, __get, __put) \
+        case attr_nr:
+
+#include GENL_MAGIC_INCLUDE_FILE
+
+/*                                                                      }}}1
+ * Magic: declare structs
+ * struct <name> {
+ *      fields
+ * };
+ *                                                                      {{{2
+ */
+
+#undef GENL_struct
+#define GENL_struct(tag_name, tag_number, s_name, s_fields)             \
+struct s_name { s_fields };
+
+#undef __field
+#define __field(attr_nr, attr_flag, name, nla_type, type, __get, __put) \
+        type name;
+
+#undef __array
+#define __array(attr_nr, attr_flag, name, nla_type, type, maxlen, __get, __put) \
+        type name[maxlen];      \
+        __u32 name ## _len;
+
+#include GENL_MAGIC_INCLUDE_FILE
+
+/* }}}1 */
+#endif /* GENL_MAGIC_STRUCT_H */
+/* vim: set foldmethod=marker nofoldenable : */