rxrpc: Make rxrpc_kernel_get_srtt() indicate validity

Fix rxrpc_kernel_get_srtt() to indicate the validity of the returned
smoothed RTT.  If we haven't had any valid samples yet, the SRTT isn't
useful.

Fixes: c410bf01933e ("rxrpc: Fix the excessive initial retransmission timeout")
Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/fs/afs/fs_probe.c b/fs/afs/fs_probe.c
index 5d9ef51..e7e98ad 100644 (file)
--- a/fs/afs/fs_probe.c
+++ b/fs/afs/fs_probe.c
@@ -161,8 +161,8 @@ responded:
                }
        }
 
-       rtt_us = rxrpc_kernel_get_srtt(call->net->socket, call->rxcall);
-       if (rtt_us < server->probe.rtt) {
+       if (rxrpc_kernel_get_srtt(call->net->socket, call->rxcall, &rtt_us) &&
+           rtt_us < server->probe.rtt) {
                server->probe.rtt = rtt_us;
                server->rtt = rtt_us;
                alist->preferred = index;

diff --git a/fs/afs/vl_probe.c b/fs/afs/vl_probe.c
index e3aa013..081b7e5 100644 (file)
--- a/fs/afs/vl_probe.c
+++ b/fs/afs/vl_probe.c
@@ -92,8 +92,8 @@ responded:
                }
        }
 
-       rtt_us = rxrpc_kernel_get_srtt(call->net->socket, call->rxcall);
-       if (rtt_us < server->probe.rtt) {
+       if (rxrpc_kernel_get_srtt(call->net->socket, call->rxcall, &rtt_us) &&
+           rtt_us < server->probe.rtt) {
                server->probe.rtt = rtt_us;
                alist->preferred = index;
                have_result = true;

diff --git a/include/net/af_rxrpc.h b/include/net/af_rxrpc.h
index 91eacbd..f6abcc0 100644 (file)
--- a/include/net/af_rxrpc.h
+++ b/include/net/af_rxrpc.h
@@ -59,7 +59,7 @@ bool rxrpc_kernel_abort_call(struct socket *, struct rxrpc_call *,
 void rxrpc_kernel_end_call(struct socket *, struct rxrpc_call *);
 void rxrpc_kernel_get_peer(struct socket *, struct rxrpc_call *,
                           struct sockaddr_rxrpc *);
-u32 rxrpc_kernel_get_srtt(struct socket *, struct rxrpc_call *);
+bool rxrpc_kernel_get_srtt(struct socket *, struct rxrpc_call *, u32 *);
 int rxrpc_kernel_charge_accept(struct socket *, rxrpc_notify_rx_t,
                               rxrpc_user_attach_call_t, unsigned long, gfp_t,
                               unsigned int);

diff --git a/net/rxrpc/peer_object.c b/net/rxrpc/peer_object.c
index ca29976..68396d0 100644 (file)
--- a/net/rxrpc/peer_object.c
+++ b/net/rxrpc/peer_object.c
@@ -502,11 +502,21 @@ EXPORT_SYMBOL(rxrpc_kernel_get_peer);
  * rxrpc_kernel_get_srtt - Get a call's peer smoothed RTT
  * @sock: The socket on which the call is in progress.
  * @call: The call to query
+ * @_srtt: Where to store the SRTT value.
  *
- * Get the call's peer smoothed RTT.
+ * Get the call's peer smoothed RTT in uS.
  */
-u32 rxrpc_kernel_get_srtt(struct socket *sock, struct rxrpc_call *call)
+bool rxrpc_kernel_get_srtt(struct socket *sock, struct rxrpc_call *call,
+                          u32 *_srtt)
 {
-       return call->peer->srtt_us >> 3;
+       struct rxrpc_peer *peer = call->peer;
+
+       if (peer->rtt_count == 0) {
+               *_srtt = 1000000; /* 1S */
+               return false;
+       }
+
+       *_srtt = call->peer->srtt_us >> 3;
+       return true;
 }
 EXPORT_SYMBOL(rxrpc_kernel_get_srtt);