rxrpc: Allow the reply time to be obtained on a client call

Allow the timestamp on the sk_buff holding the first DATA packet of a reply
to be queried.  This can then be used as a base for the expiry time
calculation on the callback promise duration indicated by an operation
result.

Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/Documentation/networking/rxrpc.txt b/Documentation/networking/rxrpc.txt
index b5407163d53bea922c58af999aeb4c49b17ed266..67879992b4c2f05cd134d1de25e29cd40abed445 100644 (file)
--- a/Documentation/networking/rxrpc.txt
+++ b/Documentation/networking/rxrpc.txt
@@ -1069,6 +1069,17 @@ The kernel interface functions are as follows:
 
      This function may transmit a PING ACK.
 
+ (*) Get reply timestamp.
+
+       bool rxrpc_kernel_get_reply_time(struct socket *sock,
+                                        struct rxrpc_call *call,
+                                        ktime_t *_ts)
+
+     This allows the timestamp on the first DATA packet of the reply of a
+     client call to be queried, provided that it is still in the Rx ring.  If
+     successful, the timestamp will be stored into *_ts and true will be
+     returned; false will be returned otherwise.
+
 
 =======================
 CONFIGURABLE PARAMETERS

diff --git a/include/net/af_rxrpc.h b/include/net/af_rxrpc.h
index f53edb3754bc4fe5203794dc444bc328dafc9c38..c4c912554dee7b6601b4ead033a8ed7db8e692ea 100644 (file)
--- a/include/net/af_rxrpc.h
+++ b/include/net/af_rxrpc.h
@@ -13,6 +13,7 @@
 #define _NET_RXRPC_H
 
 #include <linux/rxrpc.h>
+#include <linux/ktime.h>
 
 struct key;
 struct sock;
@@ -77,5 +78,7 @@ int rxrpc_kernel_retry_call(struct socket *, struct rxrpc_call *,
 int rxrpc_kernel_check_call(struct socket *, struct rxrpc_call *,
                            enum rxrpc_call_completion *, u32 *);
 u32 rxrpc_kernel_check_life(struct socket *, struct rxrpc_call *);
+bool rxrpc_kernel_get_reply_time(struct socket *, struct rxrpc_call *,
+                                ktime_t *);
 
 #endif /* _NET_RXRPC_H */

diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c
index 816b19a78809349984f3fee0fbccbc7a32cda031..eaf19ebaa964e6442cfa4117f862fb4aca9b2345 100644 (file)
--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -715,3 +715,46 @@ int rxrpc_kernel_recv_data(struct socket *sock, struct rxrpc_call *call,
        goto out;
 }
 EXPORT_SYMBOL(rxrpc_kernel_recv_data);
+
+/**
+ * rxrpc_kernel_get_reply_time - Get timestamp on first reply packet
+ * @sock: The socket that the call exists on
+ * @call: The call to query
+ * @_ts: Where to put the timestamp
+ *
+ * Retrieve the timestamp from the first DATA packet of the reply if it is
+ * in the ring.  Returns true if successful, false if not.
+ */
+bool rxrpc_kernel_get_reply_time(struct socket *sock, struct rxrpc_call *call,
+                                ktime_t *_ts)
+{
+       struct sk_buff *skb;
+       rxrpc_seq_t hard_ack, top, seq;
+       bool success = false;
+
+       mutex_lock(&call->user_mutex);
+
+       if (READ_ONCE(call->state) != RXRPC_CALL_CLIENT_RECV_REPLY)
+               goto out;
+
+       hard_ack = call->rx_hard_ack;
+       if (hard_ack != 0)
+               goto out;
+
+       seq = hard_ack + 1;
+       top = smp_load_acquire(&call->rx_top);
+       if (after(seq, top))
+               goto out;
+
+       skb = call->rxtx_buffer[seq & RXRPC_RXTX_BUFF_MASK];
+       if (!skb)
+               goto out;
+
+       *_ts = skb_get_ktime(skb);
+       success = true;
+
+out:
+       mutex_unlock(&call->user_mutex);
+       return success;
+}
+EXPORT_SYMBOL(rxrpc_kernel_get_reply_time);