rxrpc: Fix decision on when to generate an IDLE ACK

Fix the decision on when to generate an IDLE ACK by keeping a count of the
number of packets we've received, but not yet soft-ACK'd, and the number of
packets we've processed, but not yet hard-ACK'd, rather than trying to keep
track of which DATA sequence numbers correspond to those points.

We then generate an ACK when either counter exceeds 2.  The counters are
both cleared when we transcribe the information into any sort of ACK packet
for transmission.  IDLE and DELAY ACKs are skipped if both counters are 0
(ie. no change).

Fixes: b18aaa4b6b6b ("rxrpc: Send an ACK after every few DATA packets we receive")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h
index 4a3ab0ed6e0629d48c61c50b49cbdcb5d4638dea..1c714336b8635c665b02e015c5074248dc584b3e 100644 (file)
--- a/include/trace/events/rxrpc.h
+++ b/include/trace/events/rxrpc.h
@@ -1509,7 +1509,7 @@ TRACE_EVENT(rxrpc_call_reset,
                    __entry->call_serial = call->rx_serial;
                    __entry->conn_serial = call->conn->hi_serial;
                    __entry->tx_seq = call->tx_hard_ack;
-                   __entry->rx_seq = call->ackr_seen;
+                   __entry->rx_seq = call->rx_hard_ack;
                           ),
 
            TP_printk("c=%08x %08x:%08x r=%08x/%08x tx=%08x rx=%08x",

diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h
index 8465985a4cb6a2c85484bc89f117b7a4f7058cf9..dce056adb78cf44dcc57f561cad0d908f3b1ae66 100644 (file)
--- a/net/rxrpc/ar-internal.h
+++ b/net/rxrpc/ar-internal.h
@@ -680,8 +680,8 @@ struct rxrpc_call {
        u8                      ackr_reason;    /* reason to ACK */
        rxrpc_serial_t          ackr_serial;    /* serial of packet being ACK'd */
        rxrpc_seq_t             ackr_highest_seq; /* Higest sequence number received */
-       rxrpc_seq_t             ackr_consumed;  /* Highest packet shown consumed */
-       rxrpc_seq_t             ackr_seen;      /* Highest packet shown seen */
+       atomic_t                ackr_nr_unacked; /* Number of unacked packets */
+       atomic_t                ackr_nr_consumed; /* Number of packets needing hard ACK */
 
        /* RTT management */
        rxrpc_serial_t          rtt_serial[4];  /* Serial number of DATA or PING sent */

diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c
index 2e61545ad8ca5e5ad9bacf5791bbdcde1c7f436c..1145cb14d86f863efe877ceaf73f90466398d785 100644 (file)
--- a/net/rxrpc/input.c
+++ b/net/rxrpc/input.c
@@ -412,8 +412,8 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
 {
        struct rxrpc_skb_priv *sp = rxrpc_skb(skb);
        enum rxrpc_call_state state;
-       unsigned int j, nr_subpackets;
-       rxrpc_serial_t serial = sp->hdr.serial, ack_serial = 0;
+       unsigned int j, nr_subpackets, nr_unacked = 0;
+       rxrpc_serial_t serial = sp->hdr.serial, ack_serial = serial;
        rxrpc_seq_t seq0 = sp->hdr.seq, hard_ack;
        bool immediate_ack = false, jumbo_bad = false;
        u8 ack = 0;
@@ -569,6 +569,8 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
                        sp = NULL;
                }
 
+               nr_unacked++;
+
                if (last) {
                        set_bit(RXRPC_CALL_RX_LAST, &call->flags);
                        if (!ack) {
@@ -588,9 +590,14 @@ static void rxrpc_input_data(struct rxrpc_call *call, struct sk_buff *skb)
                        }
                        call->rx_expect_next = seq + 1;
                }
+               if (!ack)
+                       ack_serial = serial;
        }
 
 ack:
+       if (atomic_add_return(nr_unacked, &call->ackr_nr_unacked) > 2 && !ack)
+               ack = RXRPC_ACK_IDLE;
+
        if (ack)
                rxrpc_propose_ACK(call, ack, ack_serial,
                                  immediate_ack, true,

diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index 46aae9b7006fad7bb4909120ff88dbfc816b8224..9683617db7049c1e0db8dbd29d6d51b18fada2ad 100644 (file)
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -74,11 +74,18 @@ static size_t rxrpc_fill_out_ack(struct rxrpc_connection *conn,
                                 u8 reason)
 {
        rxrpc_serial_t serial;
+       unsigned int tmp;
        rxrpc_seq_t hard_ack, top, seq;
        int ix;
        u32 mtu, jmax;
        u8 *ackp = pkt->acks;
 
+       tmp = atomic_xchg(&call->ackr_nr_unacked, 0);
+       tmp |= atomic_xchg(&call->ackr_nr_consumed, 0);
+       if (!tmp && (reason == RXRPC_ACK_DELAY ||
+                    reason == RXRPC_ACK_IDLE))
+               return 0;
+
        /* Barrier against rxrpc_input_data(). */
        serial = call->ackr_serial;
        hard_ack = READ_ONCE(call->rx_hard_ack);
@@ -223,6 +230,10 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call, bool ping,
        n = rxrpc_fill_out_ack(conn, call, pkt, &hard_ack, &top, reason);
 
        spin_unlock_bh(&call->lock);
+       if (n == 0) {
+               kfree(pkt);
+               return 0;
+       }
 
        iov[0].iov_base = pkt;
        iov[0].iov_len  = sizeof(pkt->whdr) + sizeof(pkt->ack) + n;
@@ -259,13 +270,6 @@ int rxrpc_send_ack_packet(struct rxrpc_call *call, bool ping,
                                          ntohl(pkt->ack.serial),
                                          false, true,
                                          rxrpc_propose_ack_retry_tx);
-               } else {
-                       spin_lock_bh(&call->lock);
-                       if (after(hard_ack, call->ackr_consumed))
-                               call->ackr_consumed = hard_ack;
-                       if (after(top, call->ackr_seen))
-                               call->ackr_seen = top;
-                       spin_unlock_bh(&call->lock);
                }
 
                rxrpc_set_keepalive(call);

diff --git a/net/rxrpc/recvmsg.c b/net/rxrpc/recvmsg.c
index eca6dda26c77eba836b53ee1983d3636340cc918..250f23bc1c076d363fa8d9c3f3e3142f3ef9f7f6 100644 (file)
--- a/net/rxrpc/recvmsg.c
+++ b/net/rxrpc/recvmsg.c
@@ -260,11 +260,9 @@ static void rxrpc_rotate_rx_window(struct rxrpc_call *call)
                rxrpc_end_rx_phase(call, serial);
        } else {
                /* Check to see if there's an ACK that needs sending. */
-               if (after_eq(hard_ack, call->ackr_consumed + 2) ||
-                   after_eq(top, call->ackr_seen + 2) ||
-                   (hard_ack == top && after(hard_ack, call->ackr_consumed)))
-                       rxrpc_propose_ACK(call, RXRPC_ACK_DELAY, serial,
-                                         true, true,
+               if (atomic_inc_return(&call->ackr_nr_consumed) > 2)
+                       rxrpc_propose_ACK(call, RXRPC_ACK_IDLE, serial,
+                                         true, false,
                                          rxrpc_propose_ack_rotate_rx);
                if (call->ackr_reason && call->ackr_reason != RXRPC_ACK_DELAY)
                        rxrpc_send_ack_packet(call, false, NULL);