From 76db92af3f904b1c1d78b113510f2fb9f2eb6b29 Mon Sep 17 00:00:00 2001
From: Evan Lojewski <github@meklort.com>
Date: Sat, 11 Jul 2020 14:30:46 -0600
Subject: network: Fix a hang that can occur when the network drops during a
 transmission. (#86)

---
 libs/NCSI/ncsi.c  | 10 ++++++++--
 libs/Network/rx.c | 30 ++++++++++++++++++++++++++++--
 2 files changed, 36 insertions(+), 4 deletions(-)

(limited to 'libs')

diff --git a/libs/NCSI/ncsi.c b/libs/NCSI/ncsi.c
index 91197a4..55b7dbc 100644
--- a/libs/NCSI/ncsi.c
+++ b/libs/NCSI/ncsi.c
@@ -69,7 +69,7 @@
 uint8_t gPackageID = ((0 << PACKAGE_ID_SHIFT) | CHANNEL_ID_PACKAGE);
 
 // Response frame - global and usable by one thread at a time only.
-NetworkFrame_t gResponseFrame = 
+NetworkFrame_t gResponseFrame =
 {
     .responsePacket = {
         .DestinationAddress = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF},
@@ -717,8 +717,14 @@ void NCSI_TxPacket(uint32_t *packet, uint32_t packet_len)
     txControl.bits.LastByteCount = packet_len; /* 2 bits - automatically rounded. */
 
     // Wait for enough free space.
-    while (APE_PERI.BmcToNcTxStatus.bits.InFifo < packetWords)
+    int max_loops = 0x10000;
+    while (APE_PERI.BmcToNcTxStatus.bits.InFifo < packetWords && --max_loops)
+        ;
+
+    if (!max_loops)
     {
+        printf("Error waiting for fifo space. Dropping NCSI packet.");
+        return;
     }
 
     // Transmit.
diff --git a/libs/Network/rx.c b/libs/Network/rx.c
index f1710d2..bb721d2 100644
--- a/libs/Network/rx.c
+++ b/libs/Network/rx.c
@@ -179,8 +179,34 @@ bool Network_PassthroughRxPatcket(NetworkPort_t *port)
                 words--;
             }
 
-            while (APE_PERI.BmcToNcTxStatus.bits.InFifo < words)
-                ;
+            if (control.bits.first && APE_PERI.BmcToNcTxStatus.bits.InFifo < words)
+            {
+                // Not enough space in the fifo.
+                // Exit and check back next loop - after the network has been reset if needed.
+                return false;
+            }
+            else
+            {
+                // This can hang durning network reconfiguration events.
+                // Timeout if no packets are draining - recovery code outside of this block will handle it.
+                int max_loops = 0x10000;
+                while (APE_PERI.BmcToNcTxStatus.bits.InFifo < words && --max_loops)
+                {
+                    // TODO: This should check for a network problem and exit if that is the case.
+                }
+
+                if (!max_loops)
+                {
+                    printf("Error waiting for fifo space. Network may be down.");
+                    // Drop all packets that remain and exit.
+                    retire.bits.Head = blockid;
+                    retire.bits.Tail = rxbuf.bits.Tail;
+                    *((RegAPERxPoolRetire_t *)port->rx_retire) = retire;
+
+                    // Tell the hardware that there are no more bytes to send.
+                    APE_PERI.BmcToNcTxBufferLast.r32 = 0;
+                }
+            }
 
             if (control.bits.not_last)
             {
-- 
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