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/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