Merge tag 'rxrpc-next-20171018' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

David Howells says:

====================
rxrpc: Add bits for kernel services

Here are some patches that add a few things for kernel services to use:

 (1) Allow service upgrade to be requested and allow the resultant actual
     service ID to be obtained.

 (2) Allow the RTT time of a call to be obtained.

 (3) Allow a kernel service to find out if a call is still alive on a
     server between transmitting a request and getting the reply.

 (4) Allow data transmission to ignore signals if transmission progress is
     being made in reasonable time.  This is also usable by userspace by
     passing MSG_WAITALL to sendmsg()[*].

[*] I'm not sure this is the right interface for this or whether a sockopt
    should be used instead.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 51 insertions, 2 deletions

diff --git a/Documentation/networking/rxrpc.txt b/Documentation/networking/rxrpc.txt
index 810620153a44..b5407163d53b 100644
--- a/Documentation/networking/rxrpc.txt
+++ b/Documentation/networking/rxrpc.txt
@@ -280,6 +280,18 @@ Interaction with the user of the RxRPC socket:
      nominated by a socket option.
 
 
+Notes on sendmsg:
+
+ (*) MSG_WAITALL can be set to tell sendmsg to ignore signals if the peer is
+     making progress at accepting packets within a reasonable time such that we
+     manage to queue up all the data for transmission.  This requires the
+     client to accept at least one packet per 2*RTT time period.
+
+     If this isn't set, sendmsg() will return immediately, either returning
+     EINTR/ERESTARTSYS if nothing was consumed or returning the amount of data
+     consumed.
+
+
 Notes on recvmsg:
 
  (*) If there's a sequence of data messages belonging to a particular call on
@@ -782,7 +794,9 @@ The kernel interface functions are as follows:
 				struct key *key,
 				unsigned long user_call_ID,
 				s64 tx_total_len,
-				gfp_t gfp);
+				gfp_t gfp,
+				rxrpc_notify_rx_t notify_rx,
+				bool upgrade);
 
      This allocates the infrastructure to make a new RxRPC call and assigns
      call and connection numbers.  The call will be made on the UDP port that
@@ -803,6 +817,13 @@ The kernel interface functions are as follows:
      allows the kernel to encrypt directly to the packet buffers, thereby
      saving a copy.  The value may not be less than -1.
 
+     notify_rx is a pointer to a function to be called when events such as
+     incoming data packets or remote aborts happen.
+
+     upgrade should be set to true if a client operation should request that
+     the server upgrade the service to a better one.  The resultant service ID
+     is returned by rxrpc_kernel_recv_data().
+
      If this function is successful, an opaque reference to the RxRPC call is
      returned.  The caller now holds a reference on this and it must be
      properly ended.
@@ -850,7 +871,8 @@ The kernel interface functions are as follows:
 				   size_t size,
 				   size_t *_offset,
 				   bool want_more,
-				   u32 *_abort)
+				   u32 *_abort,
+				   u16 *_service)
 
       This is used to receive data from either the reply part of a client call
       or the request part of a service call.  buf and size specify how much
@@ -873,6 +895,9 @@ The kernel interface functions are as follows:
       If a remote ABORT is detected, the abort code received will be stored in
       *_abort and ECONNABORTED will be returned.
 
+      The service ID that the call ended up with is returned into *_service.
+      This can be used to see if a call got a service upgrade.
+
  (*) Abort a call.
 
 	void rxrpc_kernel_abort_call(struct socket *sock,
@@ -1020,6 +1045,30 @@ The kernel interface functions are as follows:
 
      It returns 0 if the call was requeued and an error otherwise.
 
+ (*) Get call RTT.
+
+	u64 rxrpc_kernel_get_rtt(struct socket *sock, struct rxrpc_call *call);
+
+     Get the RTT time to the peer in use by a call.  The value returned is in
+     nanoseconds.
+
+ (*) Check call still alive.
+
+	u32 rxrpc_kernel_check_life(struct socket *sock,
+				    struct rxrpc_call *call);
+
+     This returns a number that is updated when ACKs are received from the peer
+     (notably including PING RESPONSE ACKs which we can elicit by sending PING
+     ACKs to see if the call still exists on the server).  The caller should
+     compare the numbers of two calls to see if the call is still alive after
+     waiting for a suitable interval.
+
+     This allows the caller to work out if the server is still contactable and
+     if the call is still alive on the server whilst waiting for the server to
+     process a client operation.
+
+     This function may transmit a PING ACK.
+
 
 =======================
 CONFIGURABLE PARAMETERS