[PATCH] bonding: document undocumented active_slave sysfs entry.

["Nicolas de Pesloüan" <nicolas.2p.debian@free.fr>]

Signed-off-by: Nicolas de Pesloüan <nicolas.2p.debian@free.fr>
cc: Jay Vosburgh <fubar@us.ibm.com>
cc: Andy Gospodarek <andy@greyhouse.net>

---
 Documentation/networking/bonding.txt |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/Documentation/networking/bonding.txt b/Documentation/networking/bonding.txt
index 91df678..83b44c2 100644
--- a/Documentation/networking/bonding.txt
+++ b/Documentation/networking/bonding.txt
@@ -196,6 +196,20 @@ or, for backwards compatibility, the option value.  E.g.,
 
 	The parameters are as follows:
 
+active_slave
+
+	Specifies the active slave for modes that support it (active-backup,
+	balance-alb and balance-tlb). The possible values are one of the
+	currently enslaved slaves. The selected slave must be up and the
+	underlying link must be up too.
+	
+	Note that this is only available through the sysfs interface. No module
+	parameter by that name exists.
+
+	The default value is empty (no active slave). It will automatically be
+	set every time an active slave is selected by normal bonding operation.
+	The current active slave can be read from this sysfs entry.
+
 ad_select
 
 	Specifies the 802.3ad aggregation selection logic to use.  The
-- 
1.7.7.3