Fix Windows thread calling vTaskSuspendAll / xTaskResumeAll.

Author: Jason Carroll

source/portable/NetworkInterface/WinPCap/NetworkInterface.c

@@ -103,6 +103,20 @@ static void prvInterruptSimulatorTask( void * pvParameters );
  */
 static void prvCreateThreadSafeBuffers( void );
 
+/*
+ * This function is equivalent to uxStreamBufferAdd from
+ * FreeRTOS_Stream_Buffer.c in the case that the stream buffer is being used
+ * as a normal circular buffer (i.e. only the tail and head pointers are
+ * needed). Thus, this function does not take the offset argument, and does not
+ * update the front pointer of the stream buffer. This allows the removal of
+ * the calls to vTaskSuspendAll and xTaskResumeAll, as the head and front
+ * pointer no longer need to be atomically updated, allowing this function to be
+ * safely used by a Windows thread.
+ */
+static size_t prvStreamBufferAdd( StreamBuffer_t * pxBuffer,
+                                  const uint8_t * pucData,
+                                  size_t uxByteCount );
+
 /*
  * Utility function used to format print messages only.
  */
@@ -189,6 +203,59 @@ static void prvCreateThreadSafeBuffers( void )
         xRecvBuffer->LENGTH = xRECV_BUFFER_SIZE + 1;
     }
 }
+
+/*-----------------------------------------------------------*/
+
+static size_t prvStreamBufferAdd( StreamBuffer_t * pxBuffer,
+                                  const uint8_t * pucData,
+                                  size_t uxByteCount )
+{
+    size_t uxSpace, uxNextHead, uxFirst;
+    size_t uxCount = uxByteCount;
+
+    uxSpace = uxStreamBufferGetSpace( pxBuffer );
+
+    /* The number of bytes that can be written is the minimum of the number of
+     * bytes requested and the number available. */
+    uxCount = FreeRTOS_min_size_t( uxSpace, uxCount );
+
+    if( uxCount != 0U )
+    {
+        uxNextHead = pxBuffer->uxHead;
+
+        if( pucData != NULL )
+        {
+            /* Calculate the number of bytes that can be added in the first
+            * write - which may be less than the total number of bytes that need
+            * to be added if the buffer will wrap back to the beginning. */
+            uxFirst = FreeRTOS_min_size_t( pxBuffer->LENGTH - uxNextHead, uxCount );
+
+            /* Write as many bytes as can be written in the first write. */
+            ( void ) memcpy( &( pxBuffer->ucArray[ uxNextHead ] ), pucData, uxFirst );
+
+            /* If the number of bytes written was less than the number that
+             * could be written in the first write... */
+            if( uxCount > uxFirst )
+            {
+                /* ...then write the remaining bytes to the start of the
+                 * buffer. */
+                ( void ) memcpy( pxBuffer->ucArray, &( pucData[ uxFirst ] ), uxCount - uxFirst );
+            }
+        }
+
+        uxNextHead += uxCount;
+
+        if( uxNextHead >= pxBuffer->LENGTH )
+        {
+            uxNextHead -= pxBuffer->LENGTH;
+        }
+
+        pxBuffer->uxHead = uxNextHead;
+    }
+
+    return uxCount;
+}
+
 /*-----------------------------------------------------------*/
 
 BaseType_t xNetworkInterfaceOutput( NetworkBufferDescriptor_t * const pxNetworkBuffer,
@@ -255,7 +322,7 @@ static pcap_if_t * prvPrintAvailableNetworkInterfaces( void )
         {
             /* Print out the list of network interfaces.  The first in the list
              * is interface '1', not interface '0'. */
-            for( xInterface = pxAllNetworkInterfaces; xInterface != NULL; xInterface = xInterface->next )
+            for(xInterface = pxAllNetworkInterfaces; xInterface != NULL; xInterface = xInterface->next)
             {
                 /* The descriptions of the devices can be full of spaces, clean them
                  * a little.  printf() can only be used here because the network is not
@@ -350,7 +417,7 @@ static void prvOpenSelectedNetworkInterface( pcap_if_t * pxAllNetworkInterfaces
     /* Walk the list of devices until the selected device is located. */
     pxInterface = pxAllNetworkInterfaces;
 
-    for( x = 0L; x < ( xConfigNetworkInterfaceToUse - 1L ); x++ )
+    for(x = 0L; x < ( xConfigNetworkInterfaceToUse - 1L ); x++)
     {
         pxInterface = pxInterface->next;
     }
@@ -459,8 +526,16 @@ void pcap_callback( u_char * user,
          * Otherwise, there is no action. */
         iptraceDUMP_PACKET( ( const uint8_t * ) pkt_data, ( size_t ) pkt_header->caplen, pdTRUE );
 
-        uxStreamBufferAdd( xRecvBuffer, 0, ( const uint8_t * ) pkt_header, sizeof( *pkt_header ) );
-        uxStreamBufferAdd( xRecvBuffer, 0, ( const uint8_t * ) pkt_data, ( size_t ) pkt_header->caplen );
+        /* NOTE. The prvStreamBufferAdd function is used here in place of
+         * uxStreamBufferAdd since the uxStreamBufferAdd call will suspend
+         * the FreeRTOS scheduler to atomically update the head and front
+         * of the stream buffer. Since xRecvBuffer is being used as a regular
+         * circular buffer (i.e. only the head and tail are needed), this call
+         * only updates the head of the buffer, removing the need to suspend
+         * the scheduler, and allowing this function to be safely called from
+         * a Windows thread. */
+        prvStreamBufferAdd( xRecvBuffer, ( const uint8_t * ) pkt_header, sizeof( *pkt_header ) );
+        prvStreamBufferAdd( xRecvBuffer, ( const uint8_t * ) pkt_data, ( size_t ) pkt_header->caplen );
     }
 }
 /*-----------------------------------------------------------*/
@@ -704,7 +779,7 @@ void vNetworkInterfaceAllocateRAMToBuffers( NetworkBufferDescriptor_t pxNetworkB
     }
     else
     {
-        for( uxIndex = 0; uxIndex < ipconfigNUM_NETWORK_BUFFER_DESCRIPTORS; uxIndex++ )
+        for(uxIndex = 0; uxIndex < ipconfigNUM_NETWORK_BUFFER_DESCRIPTORS; uxIndex++)
         {
             size_t uxOffset = uxIndex * BUFFER_SIZE_ROUNDED_UP;
             NetworkBufferDescriptor_t ** ppDescriptor;