Messages in this thread | | | Date | Thu, 4 Jul 2019 10:49:13 +0200 | From | Jiri Pirko <> | Subject | Re: [PATCH net-next v6 09/15] ethtool: generic handlers for GET requests |
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Tue, Jul 02, 2019 at 01:50:24PM CEST, mkubecek@suse.cz wrote:
[...]
>+/* The structure holding data for unified processing GET requests consists of >+ * two parts: request info and reply data. Request info is related to client >+ * request and for dump request it stays constant through all processing; >+ * reply data contains data for composing a reply message. When processing >+ * a dump request, request info is filled only once but reply data is filled >+ * from scratch for each reply message. >+ * >+ * +-----------------+-----------------+------------------+-----------------+ >+ * | common_req_info | specific info | ethnl_reply_data | specific data | >+ * +-----------------+-----------------+------------------+-----------------+ >+ * |<---------- request info --------->|<----------- reply data ----------->| >+ * >+ * Request info always starts at offset 0 with struct ethnl_req_info which >+ * holds information from parsing the common header. It may be followed by >+ * other members for request attributes specific for current message type. >+ * Reply data starts with struct ethnl_reply_data which may be followed by >+ * other members holding data needed to compose a message. >+ */ >+
[...]
>+/** >+ * struct get_request_ops - unified handling of GET requests >+ * @request_cmd: command id for request (GET) >+ * @reply_cmd: command id for reply (GET_REPLY) >+ * @hdr_attr: attribute type for request header >+ * @max_attr: maximum (top level) attribute type >+ * @data_size: total length of data structure >+ * @repdata_offset: offset of "reply data" part (struct ethnl_reply_data)
For example, this looks quite scarry for me. You have one big chunk of data (according to the scheme above) specific for cmd with reply starting at arbitrary offset.
>+ * @request_policy: netlink policy for message contents >+ * @header_policy: (optional) netlink policy for request header >+ * @default_infomask: default infomask (to use if none specified) >+ * @all_reqflags: allowed request specific flags >+ * @allow_nodev_do: allow non-dump request with no device identification >+ * @parse_request: >+ * Parse request except common header (struct ethnl_req_info). Common >+ * header is already filled on entry, the rest up to @repdata_offset >+ * is zero initialized. This callback should only modify type specific >+ * request info by parsed attributes from request message. >+ * @prepare_data: >+ * Retrieve and prepare data needed to compose a reply message. Calls to >+ * ethtool_ops handlers should be limited to this callback. Common reply >+ * data (struct ethnl_reply_data) is filled on entry, type specific part >+ * after it is zero initialized. This callback should only modify the >+ * type specific part of reply data. Device identification from struct >+ * ethnl_reply_data is to be used as for dump requests, it iterates >+ * through network devices which common_req_info::dev points to the >+ * device from client request. >+ * @reply_size: >+ * Estimate reply message size. Returned value must be sufficient for >+ * message payload without common reply header. The callback may returned >+ * estimate higher than actual message size if exact calculation would >+ * not be worth the saved memory space. >+ * @fill_reply: >+ * Fill reply message payload (except for common header) from reply data. >+ * The callback must not generate more payload than previously called >+ * ->reply_size() estimated. >+ * @cleanup: >+ * Optional cleanup called when reply data is no longer needed. Can be >+ * used e.g. to free any additional data structures outside the main >+ * structure which were allocated by ->prepare_data(). When processing >+ * dump requests, ->cleanup() is called for each message. >+ * >+ * Description of variable parts of GET request handling when using the unified >+ * infrastructure. When used, a pointer to an instance of this structure is to >+ * be added to &get_requests array and generic handlers ethnl_get_doit(), >+ * ethnl_get_dumpit(), ethnl_get_start() and ethnl_get_done() used in >+ * @ethnl_genl_ops >+ */ >+struct get_request_ops { >+ u8 request_cmd; >+ u8 reply_cmd; >+ u16 hdr_attr; >+ unsigned int max_attr; >+ unsigned int data_size; >+ unsigned int repdata_offset; >+ const struct nla_policy *request_policy; >+ const struct nla_policy *header_policy; >+ u32 default_infomask; >+ u32 all_reqflags; >+ bool allow_nodev_do; >+ >+ int (*parse_request)(struct ethnl_req_info *req_info, >+ struct nlattr **tb, >+ struct netlink_ext_ack *extack); >+ int (*prepare_data)(struct ethnl_req_info *req_info, >+ struct genl_info *info); >+ int (*reply_size)(const struct ethnl_req_info *req_info); >+ int (*fill_reply)(struct sk_buff *skb, >+ const struct ethnl_req_info *req_info); >+ void (*cleanup)(struct ethnl_req_info *req_info); >+}; >+ > #endif /* _NET_ETHTOOL_NETLINK_H */ >-- >2.22.0 >
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