5 files changed, 79 insertions, 4 deletions

diff --git a/Documentation/networking/rxrpc.txt b/Documentation/networking/rxrpc.txt
index aa08d2625f05..16a924c486bf 100644
--- a/Documentation/networking/rxrpc.txt
+++ b/Documentation/networking/rxrpc.txt
@@ -926,3 +926,22 @@ adjusted through sysctls in /proc/net/rxrpc/:
      The amount of time in seconds after a transport was last used before we
      remove it from the transport list.  Whilst a transport is in existence, it
      serves to anchor the peer data and keeps the connection ID counter.
+
+ (*) rxrpc_rx_window_size
+
+     The size of the receive window in packets.  This is the maximum number of
+     unconsumed received packets we're willing to hold in memory for any
+     particular call.
+
+ (*) rxrpc_rx_mtu
+
+     The maximum packet MTU size that we're willing to receive in bytes.  This
+     indicates to the peer whether we're willing to accept jumbo packets.
+
+ (*) rxrpc_rx_jumbo_max
+
+     The maximum number of packets that we're willing to accept in a jumbo
+     packet.  Non-terminal packets in a jumbo packet must contain a four byte
+     header plus exactly 1412 bytes of data.  The terminal packet must contain
+     a four byte header plus any amount of data.  In any event, a jumbo packet
+     may not exceed rxrpc_rx_mtu in size.
diff --git a/net/rxrpc/ar-ack.c b/net/rxrpc/ar-ack.c
index 1a490d976e7e..c6be17a959a6 100644
--- a/net/rxrpc/ar-ack.c
+++ b/net/rxrpc/ar-ack.c
@@ -43,6 +43,26 @@ unsigned rxrpc_soft_ack_delay = 1 * HZ;
  */
 unsigned rxrpc_idle_ack_delay = 0.5 * HZ;
 
+/*
+ * Receive window size in packets.  This indicates the maximum number of
+ * unconsumed received packets we're willing to retain in memory.  Once this
+ * limit is hit, we should generate an EXCEEDS_WINDOW ACK and discard further
+ * packets.
+ */
+unsigned rxrpc_rx_window_size = 32;
+
+/*
+ * Maximum Rx MTU size.  This indicates to the sender the size of jumbo packet
+ * made by gluing normal packets together that we're willing to handle.
+ */
+unsigned rxrpc_rx_mtu = 5692;
+
+/*
+ * The maximum number of fragments in a received jumbo packet that we tell the
+ * sender that we're willing to handle.
+ */
+unsigned rxrpc_rx_jumbo_max = 4;
+
 static const char *rxrpc_acks(u8 reason)
 {
         static const char *const str[] = {
@@ -1195,11 +1215,11 @@ send_ACK:
         mtu = call->conn->trans->peer->if_mtu;
         mtu -= call->conn->trans->peer->hdrsize;
         ackinfo.maxMTU  = htonl(mtu);
-        ackinfo.rwind   = htonl(32);
+        ackinfo.rwind   = htonl(rxrpc_rx_window_size);
 
         /* permit the peer to send us jumbo packets if it wants to */
-        ackinfo.rxMTU   = htonl(5692);
-        ackinfo.jumbo_max = htonl(4);
+        ackinfo.rxMTU   = htonl(rxrpc_rx_mtu);
+        ackinfo.jumbo_max = htonl(rxrpc_rx_jumbo_max);
 
         hdr.serial = htonl(atomic_inc_return(&call->conn->serial));
         _proto("Tx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
diff --git a/net/rxrpc/ar-call.c b/net/rxrpc/ar-call.c
index 1e0903a2a0db..6e4d58c9b042 100644
--- a/net/rxrpc/ar-call.c
+++ b/net/rxrpc/ar-call.c
@@ -99,7 +99,7 @@ static struct rxrpc_call *rxrpc_alloc_call(gfp_t gfp)
         call->rx_data_expect = 1;
         call->rx_data_eaten = 0;
         call->rx_first_oos = 0;
-        call->ackr_win_top = call->rx_data_eaten + 1 + RXRPC_MAXACKS;
+        call->ackr_win_top = call->rx_data_eaten + 1 + rxrpc_rx_window_size;
         call->creation_jif = jiffies;
         return call;
 }
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 036e1dd84223..1ecd070e9149 100644
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -436,6 +436,9 @@ int rxrpc_reject_call(struct rxrpc_sock *);
 extern unsigned rxrpc_requested_ack_delay;
 extern unsigned rxrpc_soft_ack_delay;
 extern unsigned rxrpc_idle_ack_delay;
+extern unsigned rxrpc_rx_window_size;
+extern unsigned rxrpc_rx_mtu;
+extern unsigned rxrpc_rx_jumbo_max;
 
 void __rxrpc_propose_ACK(struct rxrpc_call *, u8, __be32, bool);
 void rxrpc_propose_ACK(struct rxrpc_call *, u8, __be32, bool);
diff --git a/net/rxrpc/sysctl.c b/net/rxrpc/sysctl.c
index cdc85e72af5d..50a98a910eb1 100644
--- a/net/rxrpc/sysctl.c
+++ b/net/rxrpc/sysctl.c
@@ -17,6 +17,9 @@
 static struct ctl_table_header *rxrpc_sysctl_reg_table;
 static const unsigned zero = 0;
 static const unsigned one = 1;
+static const unsigned four = 4;
+static const unsigned n_65535 = 65535;
+static const unsigned n_max_acks = RXRPC_MAXACKS;
 
 /*
  * RxRPC operating parameters.
@@ -94,6 +97,36 @@ static struct ctl_table rxrpc_sysctl_table[] = {
                 .proc_handler   = proc_dointvec_minmax,
                 .extra1         = (void *)&one,
         },
+
+        /* Non-time values */
+        {
+                .procname       = "rx_window_size",
+                .data           = &rxrpc_rx_window_size,
+                .maxlen         = sizeof(unsigned),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = (void *)&one,
+                .extra2         = (void *)&n_max_acks,
+        },
+        {
+                .procname       = "rx_mtu",
+                .data           = &rxrpc_rx_mtu,
+                .maxlen         = sizeof(unsigned),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = (void *)&one,
+                .extra1         = (void *)&n_65535,
+        },
+        {
+                .procname       = "rx_jumbo_max",
+                .data           = &rxrpc_rx_jumbo_max,
+                .maxlen         = sizeof(unsigned),
+                .mode           = 0644,
+                .proc_handler   = proc_dointvec_minmax,
+                .extra1         = (void *)&one,
+                .extra2         = (void *)&four,
+        },
+
         { }
 };