The sysfs "create_child" interface creates pkey based child interface but
derives the name from parent device name and pkey value.
This makes administration difficult where pkey values can change but
policies encoded with device names do not.

We add ability to create a child interface with a user specified name and a
specified pkey with a new sysfs "create_named_child" interface (and also
add a corresponding "delete_named_child" interface).

We also add a new module api interface to query pkey from a netdevice so
any kernel users of pkey based child interfaces can query it - since with
device name decoupled from pkey, it can no longer be deduced from parsing
the device name by other kernel users.

Signed-off-by: Mukesh Kacker <redacted>
Reviewed-by: Yuval Shaia <redacted>
Reviewed-by: Chien-Hua Yen <redacted>
Signed-off-by: Yuval Shaia <redacted>
---
 Documentation/infiniband/ipoib.txt        |  12 ++
 drivers/infiniband/ulp/ipoib/ipoib.h      |   3 +
 drivers/infiniband/ulp/ipoib/ipoib_main.c | 187 ++++++++++++++++++++++++++++++
 drivers/infiniband/ulp/ipoib/ipoib_vlan.c |  76 +++++++++++-
 4 files changed, 272 insertions(+), 6 deletions(-)

diff --git a/Documentation/infiniband/ipoib.txt b/Documentation/infiniband/ipoib.txt
index 47c1dd9818f2..1db53c9b2906 100644
--- a/Documentation/infiniband/ipoib.txt
+++ b/Documentation/infiniband/ipoib.txt

@@ -21,6 +21,18 @@ Partitions and P_Keys

     echo 0x8001 > /sys/class/net/ib0/delete_child

+  Interfaces with a user chosen name can be created in a similar
+  manner with a different name and P_Key, by writing them into the
+  main interface's /sys/class/net/<intf name>/create_named_child
+  For example:
+     echo "epart2 0x8002" > /sys/class/net/ib1/create_named_child
+
+   This will create an interfaces named epart2 with P_Key 0x8002 and
+   parent ib1. To remove a named subinterface, use the
+   "delete_named_child" file:
+
+     echo epart2 > /sys/class/net/ib1/delete_named_child