Fix wait loop and void cast (#24)

* Simplify EINTR/ECANCEL error handling

1. Add semaphore uninterruptible wait function
2 .Replace semaphore wait loop with a single uninterruptible wait
3. Replace all sem_xxx to nxsem_xxx

* Unify the void cast usage

1. Remove void cast for function because many place ignore the returned value witout cast
2. Replace void cast for variable with UNUSED macro

arch/x86/src/common/up_assert.c

@@ -235,7 +235,7 @@ static void up_dumpstate(void)
 #ifdef CONFIG_ARCH_USBDUMP
   /* Dump USB trace data */
 
-  (void)usbtrace_enumerate(assert_tracecallback, NULL);
+  usbtrace_enumerate(assert_tracecallback, NULL);
 #endif
 }
 #else
@@ -251,13 +251,13 @@ static void _up_assert(int errorcode)
 {
   /* Flush any buffered SYSLOG data */
 
-  (void)syslog_flush();
+  syslog_flush();
 
   /* Are we in an interrupt handler or the idle task? */
 
   if (g_current_regs || (running_task())->flink == NULL)
     {
-       (void)up_irq_save();
+       up_irq_save();
         for (;;)
           {
 #if CONFIG_BOARD_RESET_ON_ASSERT >= 1
@@ -298,7 +298,7 @@ void up_assert(const uint8_t *filename, int lineno)
 
   /* Flush any buffered SYSLOG data (from prior to the assertion) */
 
-  (void)syslog_flush();
+  syslog_flush();
 
 #if CONFIG_TASK_NAME_SIZE > 0
   _alert("Assertion failed at file:%s line: %d task: %s\n",
@@ -312,7 +312,7 @@ void up_assert(const uint8_t *filename, int lineno)
 
   /* Flush any buffered SYSLOG data (from the above) */
 
-  (void)syslog_flush();
+  syslog_flush();
 
 #ifdef CONFIG_BOARD_CRASHDUMP
   board_crashdump(up_getsp(), running_task(), filename, lineno);

arch/x86/src/common/up_blocktask.c

@@ -160,7 +160,7 @@ void up_block_task(struct tcb_s *tcb, tstate_t task_state)
           * thread at the head of the ready-to-run list.
           */
 
-         (void)group_addrenv(rtcb);
+         group_addrenv(rtcb);
 #endif
           /* Reset scheduler parameters */
 

arch/x86/src/common/up_exit.c

@@ -147,7 +147,7 @@ void _exit(int status)
    * The IRQ state will be restored when the next task is started.
    */
 
-  (void)enter_critical_section();
+  enter_critical_section();
 
   sinfo("TCB=%p exiting\n", tcb);
 
@@ -162,7 +162,7 @@ void _exit(int status)
 
   /* Destroy the task at the head of the ready to run list. */
 
-  (void)nxtask_exit();
+  nxtask_exit();
 
   /* Now, perform the context switch to the new ready-to-run task at the
    * head of the list.
@@ -177,7 +177,7 @@ void _exit(int status)
    * the ready-to-run list.
    */
 
-  (void)group_addrenv(tcb);
+  group_addrenv(tcb);
 #endif
 
   /* Reset scheduler parameters */

arch/x86/src/common/up_initialize.c

@@ -183,7 +183,7 @@ void up_initialize(void)
 #ifdef CONFIG_PSEUDOTERM_SUSV1
   /* Register the master pseudo-terminal multiplexor device */
 
-  (void)ptmx_register();
+  ptmx_register();
 #endif
 
   /* Early initialization of the system logging device.  Some SYSLOG channel
@@ -212,19 +212,19 @@ void up_initialize(void)
 #ifdef CONFIG_NETDEV_LOOPBACK
   /* Initialize the local loopback device */
 
-  (void)localhost_initialize();
+  localhost_initialize();
 #endif
 
 #ifdef CONFIG_NET_TUN
   /* Initialize the TUN device */
 
-  (void)tun_initialize();
+  tun_initialize();
 #endif
 
 #ifdef CONFIG_NETDEV_TELNET
   /* Initialize the Telnet session factory */
 
-  (void)telnet_initialize();
+  telnet_initialize();
 #endif
 
   /* Initialize USB -- device and/or host */

arch/x86/src/common/up_releasepending.c

@@ -130,7 +130,7 @@ void up_release_pending(void)
            * thread at the head of the ready-to-run list.
            */
 
-          (void)group_addrenv(rtcb);
+          group_addrenv(rtcb);
 #endif
           /* Update scheduler parameters */
 

arch/x86/src/common/up_reprioritizertr.c

@@ -183,7 +183,7 @@ void up_reprioritize_rtr(struct tcb_s *tcb, uint8_t priority)
                * thread at the head of the ready-to-run list.
                */
 
-              (void)group_addrenv(rtcb);
+              group_addrenv(rtcb);
 #endif
               /* Update scheduler parameters */
 

arch/x86/src/common/up_unblocktask.c

@@ -144,7 +144,7 @@ void up_unblock_task(struct tcb_s *tcb)
           * thread at the head of the ready-to-run list.
           */
 
-         (void)group_addrenv(rtcb);
+         group_addrenv(rtcb);
 #endif
           /* Update scheduler parameters */
 

arch/x86/src/i486/up_sigdeliver.c

@@ -106,7 +106,7 @@ void up_sigdeliver(void)
    */
 
   sinfo("Resuming\n");
-  (void)up_irq_save();
+  up_irq_save();
   rtcb->pterrno        = saved_errno;
 
   /* Modify the saved return state with the actual saved values in the

arch/x86/src/qemu/qemu_handlers.c

@@ -126,7 +126,7 @@ static uint32_t *common_handler(int irq, uint32_t *regs)
        * thread at the head of the ready-to-run list.
        */
 
-      (void)group_addrenv(NULL);
+      group_addrenv(NULL);
 #endif
     }
 #endif

arch/x86/src/qemu/qemu_keypad.c

@@ -317,5 +317,5 @@ static ssize_t keypad_read(struct file *filep, FAR char *buf, size_t buflen)
 
 void qemu_keypad(void)
 {
-  (void)register_driver("/dev/keypad", &g_keypadops, 0444, NULL);
+  register_driver("/dev/keypad", &g_keypadops, 0444, NULL);
 }

arch/x86/src/qemu/qemu_timerisr.c

@@ -123,7 +123,7 @@ void x86_timer_initialize(void)
 
   /* Attach to the timer interrupt handler */
 
-  (void)irq_attach(IRQ0, (xcpt_t)qemu_timerisr, NULL);
+  irq_attach(IRQ0, (xcpt_t)qemu_timerisr, NULL);
 
   /* Send the command byte to configure counter 0 */
 

arch/x86/src/qemu/qemu_vga.c

@@ -515,5 +515,5 @@ void qemu_vga(void)
     }
 
   memset(g_pscreen, g_bg_color, VGA_XRES * VGA_YRES);
-  (void)register_driver("/dev/lcd", &g_vgaops, 0666, NULL);
+  register_driver("/dev/lcd", &g_vgaops, 0666, NULL);
 }