tcp: track pending timers

Also removes delack timer and reuses the u32 for the pending timers
list.

Type: fix
Ticket: VPP-1923

Signed-off-by: Florin Coras <fcoras@cisco.com>
Change-Id: I4edbb72d5b2aa5e14f87659f49e675af1e834aca

6 files changed, 10 insertions, 42 deletions

diff --git a/src/vnet/tcp/tcp.c b/src/vnet/tcp/tcp.c
index 3703a4aa358..c30a69304bc 100644
--- a/src/vnet/tcp/tcp.c
+++ b/src/vnet/tcp/tcp.c
@@ -1064,7 +1064,6 @@ tcp_timer_waitclose_handler (tcp_connection_t * tc)
 static timer_expiration_handler *timer_expiration_handlers[TCP_N_TIMERS] =
 {
     tcp_timer_retransmit_handler,
-    tcp_timer_delack_handler,
     tcp_timer_persist_handler,
     tcp_timer_waitclose_handler,
     tcp_timer_retransmit_syn_handler,
@@ -1096,6 +1095,13 @@ tcp_dispatch_pending_timers (tcp_worker_ctx_t * wrk)
       if (PREDICT_FALSE (!tc))
 	continue;
 
+      /* Skip if the timer is not pending. Probably it was reset while
+       * wating for dispatch */
+      if (PREDICT_FALSE (!(tc->pending_timers & (1 << timer_id))))
+	continue;
+
+      tc->pending_timers &= ~(1 << timer_id);
+
       /* Skip timer if it was rearmed while pending dispatch */
       if (PREDICT_FALSE (tc->timers[timer_id] != TCP_TIMER_HANDLE_INVALID))
 	continue;
@@ -1241,6 +1247,7 @@ tcp_expired_timers_dispatch (u32 * expired_timers)
       TCP_EVT (TCP_EVT_TIMER_POP, connection_index, timer_id);
 
       tc->timers[timer_id] = TCP_TIMER_HANDLE_INVALID;
+      tc->pending_timers |= (1 << timer_id);
     }
 
   clib_fifo_add (wrk->pending_timers, expired_timers, n_expired);
diff --git a/src/vnet/tcp/tcp.h b/src/vnet/tcp/tcp.h
index 5c66412dfea..91783a6e025 100644
--- a/src/vnet/tcp/tcp.h
+++ b/src/vnet/tcp/tcp.h
@@ -28,7 +28,6 @@
 
 typedef void (timer_expiration_handler) (tcp_connection_t * tc);
 
-extern timer_expiration_handler tcp_timer_delack_handler;
 extern timer_expiration_handler tcp_timer_retransmit_handler;
 extern timer_expiration_handler tcp_timer_persist_handler;
 extern timer_expiration_handler tcp_timer_retransmit_syn_handler;
diff --git a/src/vnet/tcp/tcp_input.c b/src/vnet/tcp/tcp_input.c
index cc373f5b665..bdaa28ec3d0 100644
--- a/src/vnet/tcp/tcp_input.c
+++ b/src/vnet/tcp/tcp_input.c
@@ -1263,26 +1263,6 @@ tcp_session_enqueue_ooo (tcp_connection_t * tc, vlib_buffer_t * b,
   return TCP_ERROR_ENQUEUED_OOO;
 }
 
-/**
- * Check if ACK could be delayed. If ack can be delayed, it should return
- * true for a full frame. If we're always acking return 0.
- */
-always_inline int
-tcp_can_delack (tcp_connection_t * tc)
-{
-  /* Send ack if ... */
-  if (TCP_ALWAYS_ACK
-      /* just sent a rcv wnd 0
-         || (tc->flags & TCP_CONN_SENT_RCV_WND0) != 0 */
-      /* constrained to send ack */
-      || (tc->flags & TCP_CONN_SNDACK) != 0
-      /* we're almost out of tx wnd */
-      || tcp_available_cc_snd_space (tc) < 4 * tc->snd_mss)
-    return 0;
-
-  return 1;
-}
-
 static int
 tcp_buffer_discard_bytes (vlib_buffer_t * b, u32 n_bytes_to_drop)
 {
@@ -1371,14 +1351,6 @@ in_order:
   /* In order data, enqueue. Fifo figures out by itself if any out-of-order
    * segments can be enqueued after fifo tail offset changes. */
   error = tcp_session_enqueue_data (tc, b, n_data_bytes);
-  if (tcp_can_delack (tc))
-    {
-      if (!tcp_timer_is_active (tc, TCP_TIMER_DELACK))
-	tcp_timer_set (&wrk->timer_wheel, tc, TCP_TIMER_DELACK,
-		       tcp_cfg.delack_time);
-      goto done;
-    }
-
   tcp_program_ack (tc);
 
 done:
diff --git a/src/vnet/tcp/tcp_output.c b/src/vnet/tcp/tcp_output.c
index 46c5661f7c1..e9bff5b954a 100644
--- a/src/vnet/tcp/tcp_output.c
+++ b/src/vnet/tcp/tcp_output.c
@@ -1064,17 +1064,6 @@ tcp_program_retransmit (tcp_connection_t * tc)
 }
 
 /**
- * Delayed ack timer handler
- *
- * Sends delayed ACK when timer expires
- */
-void
-tcp_timer_delack_handler (tcp_connection_t * tc)
-{
-  tcp_send_ack (tc);
-}
-
-/**
  * Send window update ack
  *
  * Ensures that it will be sent only once, after a zero rwnd has been
diff --git a/src/vnet/tcp/tcp_timer.h b/src/vnet/tcp/tcp_timer.h
index d34fdcb146d..914b5aaeeb7 100644
--- a/src/vnet/tcp/tcp_timer.h
+++ b/src/vnet/tcp/tcp_timer.h
@@ -31,6 +31,7 @@ always_inline void
 tcp_timer_reset (tcp_timer_wheel_t * tw, tcp_connection_t * tc, u8 timer_id)
 {
   ASSERT (tc->c_thread_index == vlib_get_thread_index ());
+  tc->pending_timers &= ~(1 << timer_id);
   if (tc->timers[timer_id] == TCP_TIMER_HANDLE_INVALID)
     return;
 
diff --git a/src/vnet/tcp/tcp_types.h b/src/vnet/tcp/tcp_types.h
index 8b599400b8c..3cf4e9e33ef 100644
--- a/src/vnet/tcp/tcp_types.h
+++ b/src/vnet/tcp/tcp_types.h
@@ -62,7 +62,6 @@ typedef enum _tcp_state
 /** TCP timers */
 #define foreach_tcp_timer               \
   _(RETRANSMIT, "RETRANSMIT")           \
-  _(DELACK, "DELAYED ACK")              \
   _(PERSIST, "PERSIST")                 \
   _(WAITCLOSE, "WAIT CLOSE")            \
   _(RETRANSMIT_SYN, "RETRANSMIT SYN")   \
@@ -281,6 +280,7 @@ typedef struct _tcp_connection
   u8 cfg_flags;			/**< Connection configuration flags */
   u16 flags;			/**< Connection flags (see tcp_conn_flags_e) */
   u32 timers[TCP_N_TIMERS];	/**< Timer handles into timer wheel */
+  u32 pending_timers;		/**< Expired timers not yet handled */
 
   u64 segs_in;		/** RFC4022/4898 tcpHCInSegs/tcpEStatsPerfSegsIn */
   u64 bytes_in;		/** RFC4898 tcpEStatsPerfHCDataOctetsIn */