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 <David@Fries.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/connector/connector.txt

@@ -118,7 +118,7 @@ acknowledge number MUST be the same + 1.
 If we receive a message and its sequence number is not equal to one we
 are expecting, then it is a new message.  If we receive a message and
 its sequence number is the same as one we are expecting, but its
-acknowledge is not equal to the acknowledge number in the original
+acknowledge is not equal to the sequence number in the original
 message + 1, then it is a new message.
 
 Obviously, the protocol header contains the above id.

Documentation/w1/w1.generic

@@ -82,7 +82,7 @@ driver             - (standard) symlink to the w1 driver
 w1_master_add      - Manually register a slave device
 w1_master_attempts - the number of times a search was attempted
 w1_master_max_slave_count
-                   - the maximum slaves that may be attached to a master
+                   - maximum number of slaves to search for at a time
 w1_master_name     - the name of the device (w1_bus_masterX)
 w1_master_pullup   - 5V strong pullup 0 enabled, 1 disabled
 w1_master_remove   - Manually remove a slave device

Documentation/w1/w1.netlink

@@ -30,7 +30,7 @@ Protocol.
 			W1_SLAVE_CMD
 				userspace command for slave device
 				(read/write/touch)
-	__u8 res	- reserved
+	__u8 status	- error indication from kernel
 	__u16 len	- size of data attached to this header data
 	union {
 		__u8 id[8];			 - slave unique device id
@@ -44,10 +44,14 @@ Protocol.
 	__u8 cmd	- command opcode.
 			W1_CMD_READ 	- read command
 			W1_CMD_WRITE	- write command
-			W1_CMD_TOUCH	- touch command
-				(write and sample data back to userspace)
 			W1_CMD_SEARCH	- search command
 			W1_CMD_ALARM_SEARCH - alarm search command
+			W1_CMD_TOUCH	- touch command
+				(write and sample data back to userspace)
+			W1_CMD_RESET	- send bus reset
+			W1_CMD_SLAVE_ADD	- add slave to kernel list
+			W1_CMD_SLAVE_REMOVE	- remove slave from kernel list
+			W1_CMD_LIST_SLAVES	- get slaves list from kernel
 	__u8 res	- reserved
 	__u16 len	- length of data for this command
 		For read command data must be allocated like for write command
@@ -87,8 +91,7 @@ format:
 	id0 ... idN
 
 	Each message is at most 4k in size, so if number of master devices
-	exceeds this, it will be split into several messages,
-	cn.seq will be increased for each one.
+	exceeds this, it will be split into several messages.
 
 W1 search and alarm search commands.
 request:

drivers/w1/w1.h

@@ -203,7 +203,6 @@ enum w1_master_flags {
  * @search_id:		allows continuing a search
  * @refcnt:		reference count
  * @priv:		private data storage
- * @priv_size:		size allocated
  * @enable_pullup:	allows a strong pullup
  * @pullup_duration:	time for the next strong pullup
  * @flags:		one of w1_master_flags
@@ -214,7 +213,6 @@ enum w1_master_flags {
  * @dev:		sysfs device
  * @bus_master:		io operations available
  * @seq:		sequence number used for netlink broadcasts
- * @portid:		destination for the current netlink command
  */
 struct w1_master
 {
@@ -241,7 +239,6 @@ struct w1_master
 	atomic_t		refcnt;
 
 	void			*priv;
-	int			priv_size;
 
 	/** 5V strong pullup enabled flag, 1 enabled, zero disabled. */
 	int			enable_pullup;
@@ -260,11 +257,6 @@ struct w1_master
 	struct w1_bus_master	*bus_master;
 
 	u32			seq;
-	/* port id to send netlink responses to.  The value is temporarily
-	 * stored here while processing a message, set after locking the
-	 * mutex, zero before unlocking the mutex.
-	 */
-	u32			portid;
 };
 
 /**

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;