mm/iob and sched/semaphore: Work around some issues with the IOB throttle semaphore. It has some odd behaviors that can cause assertions in sem_post(). Also, it seems to get outside of its range occasionally. Need to REVISIT this.

configs/same70-xplained/README.txt

@@ -105,7 +105,7 @@ use either the VCOM or an external RS-232 driver.  Here are some options.
 
     EDBG VCOM Interface
     ---------------- --------- --------------------------
-    EDBG Singal      SAME70
+    EDBG Signal      SAME70
     ---------------- --------- --------------------------
     EDBG_CDC_UART_RX TXD1 PB4
     EDBG_CDC_UART_TX RXD1 PA21
@@ -1416,7 +1416,7 @@ Configuration sub-directories
          CONFIG_NSH_TELNETD_DAEMONSTACKSIZE=2048
          CONFIG_NSH_TELNETD_CLIENTSTACKSIZE=2048
 
-    3. NSH built-in applications are supported.  There are, however, not
+    3. NSH built-in applications are supported.  There are, however, no
        enabled built-in applications.
 
        Binary Formats:

mm/iob/iob_free.c

@@ -133,8 +133,14 @@ FAR struct iob_s *iob_free(FAR struct iob_s *iob)
    */
 
   nxsem_post(&g_iob_sem);
+  DEBUGASSERT(g_iob_sem.semcount <= CONFIG_IOB_NBUFFERS);
+
 #if CONFIG_IOB_THROTTLE > 0
   nxsem_post(&g_throttle_sem);
+
+#if 0 /* REVISIT:  This assertion fires! */
+  DEBUGASSERT(g_throttle_sem.semcount <= (CONFIG_IOB_NBUFFERS - CONFIG_IOB_THROTTLE));
+#endif
 #endif
 
 #ifdef CONFIG_IOB_NOTIFIER

sched/semaphore/sem_post.c

@@ -114,8 +114,8 @@ int nxsem_post(FAR sem_t *sem)
        * not possible to know which thread/holder should be released.
        *
        * For this reason, it is recommended that priority inheritance be
-       * disabled via nxsem_setprotocol(SEM_PRIO_NONE) when the semahore is
-       * initialixed if the semaphore is to used for signaling purposes.
+       * disabled via nxsem_setprotocol(SEM_PRIO_NONE) when the semaphore is
+       * initialized if the semaphore is to used for signaling purposes.
        */
 
       DEBUGASSERT(sem->semcount < SEM_VALUE_MAX);
@@ -165,12 +165,14 @@ int nxsem_post(FAR sem_t *sem)
 
               up_unblock_task(stcb);
             }
+#if 0 /* REVISIT:  This can fire on IOB throttle semaphore */
           else
             {
               /* This should not happen. */
 
               DEBUGPANIC();
             }
+#endif
         }
 
       /* Check if we need to drop the priority of any threads holding