Phonet: provide pipe socket option to retrieve the pipe identifier

User-space sometimes needs this information. In particular, the GPRS
context or the AT commands pipe setups may use the pipe handle as a
reference.

This removes the settable pipe handle with CONFIG_PHONET_PIPECTRLR.
It did not handle error cases correctly. Furthermore, the kernel
*could* implement a smart scheme for allocating handles (if ever
needed), but userspace really cannot.

Signed-off-by: Rémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 4 insertions, 3 deletions

diff --git a/Documentation/networking/phonet.txt b/Documentation/networking/phonet.txt
index 24ad2adba6e5..cacac968c1c3 100644
--- a/Documentation/networking/phonet.txt
+++ b/Documentation/networking/phonet.txt
@@ -181,6 +181,10 @@ The pipe protocol provides two socket options at the SOL_PNPIPE level:
     interface index of the network interface created by PNPIPE_ENCAP,
     or zero if encapsulation is off.
 
+  PNPIPE_HANDLE is a read-only integer value. It contains the underlying
+    identifier ("pipe handle") of the pipe. This is only defined for
+    socket descriptors that are already connected or being connected.
+
 
 Phonet Pipe-controller Implementation
 -------------------------------------
@@ -199,9 +203,6 @@ between itself and a remote pipe-end point (e.g. modem).
 
 The implementation adds socket options at SOL_PNPIPE level:
 
- PNPIPE_PIPE_HANDLE
-        It accepts an integer argument for setting value of pipe handle.
-
   PNPIPE_ENABLE accepts one integer value (int). If set to zero, the pipe
     is disabled. If the value is non-zero, the pipe is enabled. If the pipe
     is not (yet) connected, ENOTCONN is error is returned.