NET: Important fix to the read-ahead buffer queue managment: Consumed bytes were being trimmed from the head of the queue, but the queue head itself was not being updated. From Rony XLN

include/nuttx/net/iob.h

@@ -249,7 +249,9 @@ FAR struct iob_s *iob_remove_queue(FAR struct iob_queue_s *iobq);
  *
  ****************************************************************************/
 
+#if CONFIG_IOB_NCHAINS > 0
 FAR struct iob_s *iob_peek_queue(FAR struct iob_queue_s *iobq);
+#endif
 
 /****************************************************************************
  * Name: iob_free_queue
@@ -318,6 +320,27 @@ void iob_concat(FAR struct iob_s *iob1, FAR struct iob_s *iob2);
 
 FAR struct iob_s *iob_trimhead(FAR struct iob_s *iob, unsigned int trimlen);
 
+/****************************************************************************
+ * Name: iob_trimhead_queue
+ *
+ * Description:
+ *   Remove bytes from the beginning of an I/O chain at the head of the
+ *   queue.  Emptied I/O buffers are freed and, hence, the head of the
+ *   queue may change.
+ *
+ *   This function is just a wrapper around iob_trimhead() that assures that
+ *   the iob at the head of queue is modified with the trimming operations.
+ *
+ * Returned Value:
+ *   The new iob at the head of the queue is returned.
+ *
+ ****************************************************************************/
+
+#if CONFIG_IOB_NCHAINS > 0
+FAR struct iob_s *iob_trimhead_queue(FAR struct iob_queue_s *qhead,
+                                     unsigned int trimlen);
+#endif
+
 /****************************************************************************
  * Name: iob_trimtail
  *

net/iob/Make.defs

@@ -41,7 +41,7 @@ NET_CSRCS += iob_add_queue.c iob_alloc.c iob_alloc_qentry.c iob_clone.c
 NET_CSRCS += iob_concat.c iob_copyin.c iob_copyout.c iob_contig.c iob_free.c
 NET_CSRCS += iob_free_chain.c iob_free_qentry.c iob_free_queue.c
 NET_CSRCS += iob_initialize.c iob_pack.c iob_peek_queue.c iob_remove_queue.c
-NET_CSRCS += iob_trimhead.c iob_trimtail.c
+NET_CSRCS += iob_trimhead.c iob_trimhead_queue.c iob_trimtail.c
 
 ifeq ($(CONFIG_DEBUG),y)
 NET_CSRCS += iob_dump.c

net/iob/iob_trimhead_queue.c

@@ -0,0 +1,127 @@
+/****************************************************************************
+ * net/iob/iob_trimhead_queue.c
+ *
+ *   Copyright (C) 2014 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#if defined(CONFIG_DEBUG) && defined(CONFIG_IOB_DEBUG)
+/* Force debug output (from this file only) */
+
+#  undef  CONFIG_DEBUG_NET
+#  define CONFIG_DEBUG_NET 1
+#endif
+
+#include <assert.h>
+#include <debug.h>
+
+#include <nuttx/net/iob.h>
+
+#include "iob.h"
+
+#if CONFIG_IOB_NCHAINS > 0
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+#ifndef NULL
+#  define NULL ((FAR void *)0)
+#endif
+
+/****************************************************************************
+ * Private Types
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: iob_trimhead_queue
+ *
+ * Description:
+ *   Remove bytes from the beginning of an I/O chain at the head of the
+ *   queue.  Emptied I/O buffers are freed and, hence, the head of the
+ *   queue may change.
+ *
+ *   This function is just a wrapper around iob_trimhead() that assures that
+ *   the I/O buffer chain at the head of queue is modified with the trimming
+ *   operation.
+ *
+ * Returned Value:
+ *   The new I/O buffer chain at the head of the queue is returned.
+ *
+ ****************************************************************************/
+
+FAR struct iob_s *iob_trimhead_queue(FAR struct iob_queue_s *qhead,
+                                     unsigned int trimlen)
+{
+  FAR struct iob_qentry_s *qentry;
+  FAR struct iob_s *iob = NULL;
+
+  /* Peek at the I/O buffer chain container at the head of the queue */
+
+  qentry = qhead->qh_head;
+  if (qentry)
+    {
+      /* Verify that the queue entry contains an I/O buffer chain */
+
+      iob = qentry->qe_head;
+      if (iob)
+        {
+          /* Trim the I/Buffer chain and update the queue head */
+
+          iob = iob_trimhead(iob, trimlen);
+          qentry->qe_head = iob;
+        }
+    }
+
+  /* Return the new I/O buffer chain at the head of the queue */
+
+  return iob;
+}
+
+#endif /* CONFIG_IOB_NCHAINS > 0 */

net/socket/recvfrom.c

@@ -376,11 +376,12 @@ static inline void recvfrom_readahead(struct recvfrom_s *pstate)
         }
       else
         {
-          /* The bytes that we have received from the from of the I/O
-           * buffer chain.
+          /* The bytes that we have received from the head of the I/O
+           * buffer chain (probably changing the head of the I/O
+           * buffer queue).
            */
 
-          (void)iob_trimhead(iob, recvlen);
+          (void)iob_trimhead_queue(&conn->readahead, recvlen);
         }
     }
 }