More fixes to problems noted by cppcheck. Some are kind of risky; some are real bugs.

fs/nxffs/nxffs_stat.c

@@ -151,7 +151,6 @@ int nxffs_stat(FAR struct inode *mountpt, FAR const char *relpath,
 
   memset(buf, 0, sizeof(struct stat));
   buf->st_blksize = volume->geo.blocksize;
-  buf->st_blocks  = entry.datlen / (volume->geo.blocksize - SIZEOF_NXFFS_BLOCK_HDR);
 
   /* The requested directory must be the volume-relative "root" directory */
 
@@ -166,6 +165,7 @@ int nxffs_stat(FAR struct inode *mountpt, FAR const char *relpath,
           goto errout_with_semaphore;
         }
 
+      buf->st_blocks  = entry.datlen / (volume->geo.blocksize - SIZEOF_NXFFS_BLOCK_HDR);
       buf->st_mode    = S_IFREG|S_IXOTH|S_IXGRP|S_IXUSR;
       buf->st_size    = entry.datlen;
       buf->st_atime   = entry.utc;

libc/syslog/lib_syslog.c

@@ -108,7 +108,7 @@ static inline int vsyslog_internal(FAR const char *fmt, va_list ap)
 
   /* Get the current time */
 
-  ret = clock_systimespec(&ts);
+  (void)clock_systimespec(&ts);
 #endif
 
 #if defined(CONFIG_SYSLOG)

libc/unistd/lib_execl.c

@@ -146,6 +146,7 @@ int execl(FAR const char *path, ...)
       if (++nargs > MAX_EXECL_ARGS)
         {
           set_errno(E2BIG);
+          va_end(ap);
           return ERROR;
         }
     }

net/iob/iob_trimtail.c

@@ -86,7 +86,6 @@ FAR struct iob_s *iob_trimtail(FAR struct iob_s *iob, unsigned int trimlen)
   FAR struct iob_s *entry;
   FAR struct iob_s *penultimate;
   FAR struct iob_s *last;
-  unsigned int iosize;
   int len;
 
   nlldbg("iob=%p pktlen=%d trimlen=%d\n", iob, iob->io_pktlen, trimlen);
@@ -105,14 +104,9 @@ FAR struct iob_s *iob_trimtail(FAR struct iob_s *iob, unsigned int trimlen)
 
           penultimate = NULL;
           last = NULL;
-          iosize = 0;
 
           for (entry = iob; entry; entry = entry->io_flink)
             {
-              /* Accumulate the total size of all buffers in the list */
-
-              iosize += entry->io_len;
-
               /* Remember the last and the next to the last in the chain */
 
               penultimate = last;

net/route/netdev_router.c

@@ -163,7 +163,6 @@ void netdev_router(FAR struct net_driver_s *dev, net_ipaddr_t target,
 #else
       net_ipaddr_copy(*router, match.target);
 #endif
-      ret = OK;
     }
   else
     {

sched/init/os_start.c

@@ -341,6 +341,7 @@ void os_start(void)
 
   sem_initialize();
 
+#if defined(MM_KERNEL_USRHEAP_INIT) || defined(CONFIG_MM_KERNEL_HEAP) || defined(CONFIG_MM_PGALLOC)
   /* Initialize the memory manager */
 
   {
@@ -375,6 +376,7 @@ void os_start(void)
     mm_pginitialize(heap_start, heap_size);
 #endif
   }
+#endif
 
 #if defined(CONFIG_SCHED_HAVE_PARENT) && defined(CONFIG_SCHED_CHILD_STATUS)
   /* Initialize tasking data structures */

sched/sched/sched_timerexpiration.c

@@ -467,12 +467,9 @@ static void sched_timer_start(unsigned int ticks)
        ret = up_timer_start(&ts);
 #endif
 
-      /* [Re-]start the interval timer */
-
-      ret = up_timer_start(&ts);
       if (ret < 0)
         {
-          slldbg("ERROR: up_timer_start failed: %d\n");
+          slldbg("ERROR: up_timer_start/up_alarm_start failed: %d\n");
           UNUSED(ret);
         }
     }

sched/wdog/wd_start.c

@@ -452,7 +452,7 @@ unsigned int wd_timer(int ticks)
       /* There are.  Decrement the lag counter */
 
       wdog->lag -= decr;
-      ticks     -= ticks;
+      ticks     -= decr;
 
       /* Check if the watchdog at the head of the list is ready to run */
 

sched/wqueue/kwork_inherit.c

@@ -176,9 +176,11 @@ static void lpwork_boostworker(pid_t wpid, uint8_t reqprio)
 static void lpwork_restoreworker(pid_t wpid, uint8_t reqprio)
 {
   FAR struct tcb_s *wtcb;
+#if CONFIG_SEM_NNESTPRIO > 0
   uint8_t wpriority;
   int index;
   int selected;
+#endif
 
   /* Get the TCB of the low priority worker thread from the process ID. */