From 3b81e58047cfc76ce9f8c72aebfca22080049873 Mon Sep 17 00:00:00 2001
From: Gregory Nutt <gnutt@nuttx.org>
Date: Sat, 28 Jun 2014 11:35:14 -0600
Subject: [PATCH] NET:  Fix some errors in recent network I/O buffering when
 stack runs from interrupt level

---
 include/nuttx/net/net.h |  2 +-
 net/iob/iob_alloc.c     | 16 ++++++++++++----
 sched/os_start.c        |  7 +------
 sched/sem_trywait.c     |  4 ++--
 4 files changed, 16 insertions(+), 13 deletions(-)

diff --git a/include/nuttx/net/net.h b/include/nuttx/net/net.h
index 707a499b004..fb7ff913663 100644
--- a/include/nuttx/net/net.h
+++ b/include/nuttx/net/net.h
@@ -156,7 +156,7 @@ int net_checksd(int fd, int oflags);
  * under sched/
  */
 
-void weak_function net_initialize(void);
+void net_initialize(void);
 void net_initlist(FAR struct socketlist *list);
 void net_releaselist(FAR struct socketlist *list);
 
diff --git a/net/iob/iob_alloc.c b/net/iob/iob_alloc.c
index 179908d4693..1bfbab7c41d 100644
--- a/net/iob/iob_alloc.c
+++ b/net/iob/iob_alloc.c
@@ -107,8 +107,7 @@ static FAR struct iob_s *iob_tryalloc(bool throttled)
 #if CONFIG_IOB_THROTTLE > 0
   /* If there are free I/O buffers for this allocation */
 
-  DEBUGVERIFY(sem_getvalue(sem, &semcount));
-  if (semcount > 0)
+  if (sem->semcount > 0)
 #endif
     {
       /* Take the I/O buffer from the head of the free list */
@@ -122,9 +121,18 @@ static FAR struct iob_s *iob_tryalloc(bool throttled)
            */
 
           g_iob_freelist = iob->io_flink;
-          DEBUGVERIFY(sem_trywait(&g_iob_sem));
+
+          /* Take a semaphore count.  Note that we cannot do this in
+           * in the orthodox way by calling sem_wait() or sem_trywait()
+           * because this function may be called from an interrupt
+           * handler. Fortunately we know at at least one free buffer
+           * so a simple decrement is all that is needed.
+           */
+
+          g_iob_sem.semcount--;
+          DEBUGASSERT(g_iob_sem.semcount >= 0);
+
 #if CONFIG_IOB_THROTTLE > 0
-          //DEBUGVERIFY(sem_trywait(&g_throttle_sem));
           g_throttle_sem.semcount--;
           DEBUGASSERT(g_throttle_sem.semcount >= -CONFIG_IOB_THROTTLE);
 #endif
diff --git a/sched/os_start.c b/sched/os_start.c
index a7cd4b9f4ff..194b42ab2ba 100644
--- a/sched/os_start.c
+++ b/sched/os_start.c
@@ -448,12 +448,7 @@ void os_start(void)
   /* Initialize the network system */
 
 #ifdef CONFIG_NET
-#if 0
-  if (net_initialize != NULL)
-#endif
-    {
-      net_initialize();
-    }
+  net_initialize();
 #endif
 
   /* The processor specific details of running the operating system
diff --git a/sched/sem_trywait.c b/sched/sem_trywait.c
index ce3e80b3ac5..38de330a519 100644
--- a/sched/sem_trywait.c
+++ b/sched/sem_trywait.c
@@ -116,8 +116,8 @@ int sem_trywait(FAR sem_t *sem)
 
       saved_state = irqsave();
 
-      /* Any further errors could only be occurred because the semaphore
-       * is not available.
+      /* Any further errors could only occurr because the semaphore is not
+       * available.
        */
 
       set_errno(EAGAIN);