[PATCH net-next 10/15] rxrpc: Don't call the tx_ack tracepoint if don't generate an ACK

[David Howells]

rxrpc_send_call_packet() is invoking the tx_ack tracepoint before it checks
whether there's an ACK to transmit (another thread may jump in and transmit
it).

Fix this by only invoking the tracepoint if we get a valid ACK to transmit.

Further, only allocate a serial number if we're going to actually transmit
something.

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

 net/rxrpc/output.c |   26 +++++++++++---------------
 1 file changed, 11 insertions(+), 15 deletions(-)

diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c
index 282cb1e36d06..5c1e008a5323 100644
--- a/net/rxrpc/output.c
+++ b/net/rxrpc/output.c
@@ -80,9 +80,6 @@ static size_t rxrpc_fill_out_ack(struct rxrpc_call *call,
        pkt->ackinfo.rwind      = htonl(call->rx_winsize);
        pkt->ackinfo.jumbo_max  = htonl(jmax);
 
-       trace_rxrpc_tx_ack(call, hard_ack + 1, serial, call->ackr_reason,
-                          top - hard_ack);
-
        *ackp++ = 0;
        *ackp++ = 0;
        *ackp++ = 0;
@@ -119,8 +116,6 @@ int rxrpc_send_call_packet(struct rxrpc_call *call, u8 type)
                return -ENOMEM;
        }
 
-       serial = atomic_inc_return(&conn->serial);
-
        msg.msg_name    = &call->peer->srx.transport;
        msg.msg_namelen = call->peer->srx.transport_len;
        msg.msg_control = NULL;
@@ -131,7 +126,6 @@ int rxrpc_send_call_packet(struct rxrpc_call *call, u8 type)
        pkt->whdr.cid           = htonl(call->cid);
        pkt->whdr.callNumber    = htonl(call->call_id);
        pkt->whdr.seq           = 0;
-       pkt->whdr.serial        = htonl(serial);
        pkt->whdr.type          = type;
        pkt->whdr.flags         = conn->out_clientflag;
        pkt->whdr.userStatus    = 0;
@@ -157,14 +151,6 @@ int rxrpc_send_call_packet(struct rxrpc_call *call, u8 
type)
 
                spin_unlock_bh(&call->lock);
 
-               _proto("Tx ACK %%%u { m=%hu f=#%u p=#%u s=%%%u r=%s n=%u }",
-                      serial,
-                      ntohs(pkt->ack.maxSkew),
-                      ntohl(pkt->ack.firstPacket),
-                      ntohl(pkt->ack.previousPacket),
-                      ntohl(pkt->ack.serial),
-                      rxrpc_acks(pkt->ack.reason),
-                      pkt->ack.nAcks);
 
                iov[0].iov_len += sizeof(pkt->ack) + n;
                iov[1].iov_base = &pkt->ackinfo;
@@ -176,7 +162,6 @@ int rxrpc_send_call_packet(struct rxrpc_call *call, u8 type)
        case RXRPC_PACKET_TYPE_ABORT:
                abort_code = call->abort_code;
                pkt->abort_code = htonl(abort_code);
-               _proto("Tx ABORT %%%u { %d }", serial, abort_code);
                iov[0].iov_len += sizeof(pkt->abort_code);
                len += sizeof(pkt->abort_code);
                ioc = 1;
@@ -188,6 +173,17 @@ int rxrpc_send_call_packet(struct rxrpc_call *call, u8 
type)
                goto out;
        }
 
+       serial = atomic_inc_return(&conn->serial);
+       pkt->whdr.serial = htonl(serial);
+       switch (type) {
+       case RXRPC_PACKET_TYPE_ACK:
+               trace_rxrpc_tx_ack(call,
+                                  ntohl(pkt->ack.firstPacket),
+                                  ntohl(pkt->ack.serial),
+                                  pkt->ack.reason, pkt->ack.nAcks);
+               break;
+       }
+
        if (ping) {
                call->ackr_ping = serial;
                smp_wmb();