From 8a0427d192e6043834414210dd14cc1289daff18 Mon Sep 17 00:00:00 2001 From: David Fries Date: Tue, 8 Apr 2014 22:37:09 -0500 Subject: w1: optional bundling of netlink kernel replies Applications can submit a set of commands in one packet to the kernel, and in some cases it is required such as reading the temperature sensor results. This adds an option W1_CN_BUNDLE to the flags of cn_msg to request the kernel to reply in one packet for efficiency. The cn_msg flags now check for unknown flag values and return an error if one is seen. See "Proper handling of unknown flags in system calls" http://lwn.net/Articles/588444/ This corrects the ack values returned as per the protocol standard, namely the original ack for status messages and seq + 1 for all others such as the data returned from a read. Some of the common variable names have been standardized as follows. struct cn_msg *cn struct w1_netlink_msg *msg struct w1_netlink_cmd *cmd struct w1_master *dev When an argument and a function scope variable would collide, add req_ to the argument. Signed-off-by: David Fries Acked-by: Evgeniy Polyakov Signed-off-by: Greg Kroah-Hartman --- drivers/w1/w1_netlink.h | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) (limited to 'drivers/w1/w1_netlink.h') diff --git a/drivers/w1/w1_netlink.h b/drivers/w1/w1_netlink.h index 1e9504e67650..c99a9ce05e62 100644 --- a/drivers/w1/w1_netlink.h +++ b/drivers/w1/w1_netlink.h @@ -27,6 +27,17 @@ #include "w1.h" +/** + * enum w1_cn_msg_flags - bitfield flags for struct cn_msg.flags + * + * @W1_CN_BUNDLE: Request bundling replies into fewer messagse. Be prepared + * to handle multiple struct cn_msg, struct w1_netlink_msg, and + * struct w1_netlink_cmd in one packet. + */ +enum w1_cn_msg_flags { + W1_CN_BUNDLE = 1, +}; + /** * enum w1_netlink_message_types - message type * @@ -49,6 +60,19 @@ enum w1_netlink_message_types { W1_LIST_MASTERS, }; +/** + * struct w1_netlink_msg - holds w1 message type, id, and result + * + * @type: one of enum w1_netlink_message_types + * @status: kernel feedback for success 0 or errno failure value + * @len: length of data following w1_netlink_msg + * @id: union holding master bus id (msg.id) and slave device id (id[8]). + * @data: start address of any following data + * + * The base message structure for w1 messages over netlink. + * The netlink connector data sequence is, struct nlmsghdr, struct cn_msg, + * then one or more struct w1_netlink_msg (each with optional data). + */ struct w1_netlink_msg { __u8 type; @@ -66,6 +90,7 @@ struct w1_netlink_msg /** * enum w1_commands - commands available for master or slave operations + * * @W1_CMD_READ: read len bytes * @W1_CMD_WRITE: write len bytes * @W1_CMD_SEARCH: initiate a standard search, returns only the slave @@ -93,6 +118,17 @@ enum w1_commands { W1_CMD_MAX }; +/** + * struct w1_netlink_cmd - holds the command and data + * + * @cmd: one of enum w1_commands + * @res: reserved + * @len: length of data following w1_netlink_cmd + * @data: start address of any following data + * + * One or more struct w1_netlink_cmd is placed starting at w1_netlink_msg.data + * each with optional data. + */ struct w1_netlink_cmd { __u8 cmd; -- cgit v1.2.1