sched/wdog: wd_start() is an internal OS function and should not set the errno value. Reviewed and updated every call to wd_start() to verify if return value is used and if so if the errno value is accessed.

Documentation/NuttxPortingGuide.html

@@ -12,7 +12,7 @@
       <h1><big><font color="#3c34ec">
         <i>NuttX RTOS Porting Guide</i>
       </font></big></h1>
-      <p>Last Updated: October 12, 2017</p>
+      <p>Last Updated: January 31, 2018</p>
     </td>
   </tr>
 </table>
@@ -2605,7 +2605,7 @@ pointer to a watchdog structure.
 <p>
 <b>Returned Value:</b>
 <ul>
-<li>OK or ERROR
+<li>Zero (<code>OK</code>) is returned on success; a negated <code>errno</code> value is return to indicate the nature of any failure.
 </ul>
 
 <p>
@@ -2662,7 +2662,7 @@ wd_start() on a given watchdog ID has any effect.
 <p>
 <b>Returned Value:</b>
 <ul>
-<li>OK or ERROR
+<li>Zero (<code>OK</code>) is returned on success; a negated <code>errno</code> value is return to indicate the nature of any failure.
 </ul>
 
 <p>

arch/arm/src/efm32/efm32_spi.c

@@ -1493,7 +1493,7 @@ static void spi_exchange(struct spi_dev_s *dev, const void *txbuffer,
       ret = wd_start(priv->wdog, (int)ticks, spi_dma_timeout, 1, (uint32_t)priv);
       if (ret < 0)
         {
-          spierr("ERROR: Failed to start timeout\n");
+          spierr("ERROR: Failed to start timeout: %d\n", ret);
         }
 
       /* Then wait for each to complete.  TX should complete first */

arch/arm/src/kinetis/kinetis_i2c.c

@@ -1183,7 +1183,7 @@ static int kinetis_i2c_transfer(struct i2c_master_s *dev,
 
       /* Wait for transfer complete */
 
-      wd_start(priv->timeout, I2C_TIMEOUT, kinetis_i2c_timeout, 1,
+      (void)wd_start(priv->timeout, I2C_TIMEOUT, kinetis_i2c_timeout, 1,
                      (uint32_t)priv);
       kinetis_i2c_wait(priv);
 

arch/arm/src/kinetis/kinetis_sdhc.c

@@ -2465,7 +2465,7 @@ static sdio_eventset_t kinetis_eventwait(FAR struct sdio_dev_s *dev,
       delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)kinetis_eventtimeout,
                        1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
           mcerr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/kinetis/kinetis_usbdev.c

@@ -1112,7 +1112,8 @@ static void khci_delayedrestart(struct khci_usbdev_s *priv, uint8_t epno)
 
   /* And start (or re-start) the watchdog timer */
 
-  wd_start(priv->wdog, RESTART_DELAY, khci_rqrestart, 1, (uint32_t)priv);
+  (void)wd_start(priv->wdog, RESTART_DELAY, khci_rqrestart, 1,
+                 (uint32_t)priv);
 }
 
 /****************************************************************************

arch/arm/src/lpc11xx/lpc11_i2c.c

@@ -215,7 +215,8 @@ static int lpc11_i2c_start(struct lpc11_i2cdev_s *priv)
            priv->base + LPC11_I2C_CONCLR_OFFSET);
   putreg32(I2C_CONSET_STA, priv->base + LPC11_I2C_CONSET_OFFSET);
 
-  wd_start(priv->timeout, I2C_TIMEOUT, lpc11_i2c_timeout, 1, (uint32_t)priv);
+  (void)wd_start(priv->timeout, I2C_TIMEOUT, lpc11_i2c_timeout, 1,
+                 (uint32_t)priv);
   nxsem_wait(&priv->wait);
 
   wd_cancel(priv->timeout);

arch/arm/src/lpc17xx/lpc17_i2c.c

@@ -215,7 +215,8 @@ static int lpc17_i2c_start(struct lpc17_i2cdev_s *priv)
            priv->base + LPC17_I2C_CONCLR_OFFSET);
   putreg32(I2C_CONSET_STA, priv->base + LPC17_I2C_CONSET_OFFSET);
 
-  wd_start(priv->timeout, I2C_TIMEOUT, lpc17_i2c_timeout, 1, (uint32_t)priv);
+  (void)wd_start(priv->timeout, I2C_TIMEOUT, lpc17_i2c_timeout, 1,
+                 (uint32_t)priv);
   nxsem_wait(&priv->wait);
 
   wd_cancel(priv->timeout);

arch/arm/src/lpc17xx/lpc17_sdcard.c

@@ -2307,7 +2307,7 @@ static sdio_eventset_t lpc17_eventwait(FAR struct sdio_dev_s *dev,
       delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)lpc17_eventtimeout,
                        1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
           mcerr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/lpc2378/lpc23xx_i2c.c

@@ -220,7 +220,8 @@ static int lpc2378_i2c_start(struct lpc2378_i2cdev_s *priv)
            priv->base + I2C_CONCLR_OFFSET);
   putreg32(I2C_CONSET_STA, priv->base + I2C_CONSET_OFFSET);
 
-  wd_start(priv->timeout, I2C_TIMEOUT, lpc2378_i2c_timeout, 1, (uint32_t)priv);
+  (void)wd_start(priv->timeout, I2C_TIMEOUT, lpc2378_i2c_timeout, 1,
+                 (uint32_t)priv);
   nxsem_wait(&priv->wait);
 
   wd_cancel(priv->timeout);

arch/arm/src/lpc31xx/lpc31_i2c.c

@@ -490,7 +490,7 @@ static int i2c_transfer(FAR struct i2c_master_s *dev, FAR struct i2c_msg_s *msgs
 
   /* Start a watchdog to timeout the transfer if the bus is locked up... */
 
-  wd_start(priv->timeout, I2C_TIMEOUT, i2c_timeout, 1, (uint32_t)priv);
+  (void)wd_start(priv->timeout, I2C_TIMEOUT, i2c_timeout, 1, (uint32_t)priv);
 
   /* Wait for the transfer to complete */
 

arch/arm/src/lpc43xx/lpc43_i2c.c

@@ -202,7 +202,8 @@ static int lpc43_i2c_start(struct lpc43_i2cdev_s *priv)
            priv->base + LPC43_I2C_CONCLR_OFFSET);
   putreg32(I2C_CONSET_STA, priv->base + LPC43_I2C_CONSET_OFFSET);
 
-  wd_start(priv->timeout, I2C_TIMEOUT, lpc43_i2c_timeout, 1, (uint32_t)priv);
+  (void)wd_start(priv->timeout, I2C_TIMEOUT, lpc43_i2c_timeout, 1,i
+                 (uint32_t)priv);
   nxsem_wait(&priv->wait);
 
   wd_cancel(priv->timeout);

arch/arm/src/lpc43xx/lpc43_sdmmc.c

@@ -2262,7 +2262,7 @@ static sdio_eventset_t lpc43_eventwait(FAR struct sdio_dev_s *dev,
       delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)lpc43_eventtimeout,
                        1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
           mcerr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/lpc54xx/lpc54_i2c_master.c

@@ -765,10 +765,9 @@ static int lpc54_i2c_transfer(FAR struct i2c_master_s *dev,
   priv->result = OK;
 
   /* Set up the transfer timeout */
-  /* wd_start(priv->timeout ...);  */
 
-  wd_start(priv->timeout, priv->nmsgs * I2C_WDOG_TIMEOUT, lpc54_i2c_timeout,
+  (void)wd_start(priv->timeout, priv->nmsgs * I2C_WDOG_TIMEOUT,
-           1, (uint32_t)priv);
+                 lpc54_i2c_timeout, 1, (uint32_t)priv);
 
   /* Initiate the transfer */
 

arch/arm/src/lpc54xx/lpc54_sdmmc.c

@@ -2262,7 +2262,7 @@ static sdio_eventset_t lpc54_eventwait(FAR struct sdio_dev_s *dev,
       delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)lpc54_eventtimeout,
                        1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
           mcerr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/sam34/sam_hsmci.c

@@ -2317,7 +2317,7 @@ static sdio_eventset_t sam_eventwait(FAR struct sdio_dev_s *dev,
       delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)sam_eventtimeout,
                        1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
           mcerr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/sam34/sam_spi.c

@@ -1590,7 +1590,7 @@ static void spi_exchange(struct spi_dev_s *dev, const void *txbuffer,
 
       ret = wd_start(spics->dmadog, DMA_TIMEOUT_TICKS,
                      (wdentry_t)spi_dmatimeout, 1, (uint32_t)spics);
-      if (ret != OK)
+      if (ret < 0)
         {
            spierr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/sam34/sam_twi.c

@@ -386,7 +386,7 @@ static int twi_wait(struct twi_dev_s *priv)
 {
   /* Start a timeout to avoid hangs */
 
-  wd_start(priv->timeout, TWI_TIMEOUT, twi_timeout, 1, (uint32_t)priv);
+  (void)wd_start(priv->timeout, TWI_TIMEOUT, twi_timeout, 1, (uint32_t)priv);
 
   /* Wait for either the TWI transfer or the timeout to complete */
 

arch/arm/src/sama5/sam_hsmci.c

@@ -2745,7 +2745,7 @@ static sdio_eventset_t sam_eventwait(FAR struct sdio_dev_s *dev,
       delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)sam_eventtimeout,
                        1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
            lcderr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/sama5/sam_spi.c

@@ -1520,7 +1520,7 @@ static void spi_exchange(struct spi_dev_s *dev, const void *txbuffer,
 
       ret = wd_start(spics->dmadog, DMA_TIMEOUT_TICKS,
                      (wdentry_t)spi_dmatimeout, 1, (uint32_t)spics);
-      if (ret != OK)
+      if (ret < 0)
         {
            spierr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/sama5/sam_tsd.c

@@ -597,7 +597,8 @@ static void sam_tsd_bottomhalf(void *arg)
        * this case; we rely on the timer expiry to get us going again.
        */
 
-      wd_start(priv->wdog, TSD_WDOG_DELAY, sam_tsd_expiry, 1, (uint32_t)priv);
+      (void)wd_start(priv->wdog, TSD_WDOG_DELAY, sam_tsd_expiry, 1,
+                     (uint32_t)priv);
       ier = 0;
       goto ignored;
     }
@@ -675,7 +676,8 @@ static void sam_tsd_bottomhalf(void *arg)
 
       /* Continue to sample the position while the pen is down */
 
-      wd_start(priv->wdog, TSD_WDOG_DELAY, sam_tsd_expiry, 1, (uint32_t)priv);
+      (void)wd_start(priv->wdog, TSD_WDOG_DELAY, sam_tsd_expiry, 1,
+                     (uint32_t)priv);
 
       /* Check the thresholds.  Bail if (1) this is not the first
        * measurement and (2) there is no significant difference from

arch/arm/src/sama5/sam_twi.c

@@ -487,7 +487,7 @@ static int twi_wait(struct twi_dev_s *priv, unsigned int size)
    * TWI transfer stalls.
    */
 
-  wd_start(priv->timeout, timeout, twi_timeout, 1, (uint32_t)priv);
+  (void)wd_start(priv->timeout, timeout, twi_timeout, 1, (uint32_t)priv);
 
   /* Wait for either the TWI transfer or the timeout to complete */
 

arch/arm/src/samv7/sam_hsmci.c

@@ -2791,7 +2791,7 @@ static sdio_eventset_t sam_eventwait(FAR struct sdio_dev_s *dev,
       delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)sam_eventtimeout,
                        1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
            mcerr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/samv7/sam_qspi.c

@@ -885,7 +885,7 @@ static int qspi_memory_dma(struct sam_qspidev_s *priv,
 
       ret = wd_start(priv->dmadog, DMA_TIMEOUT_TICKS,
                      (wdentry_t)qspi_dma_timeout, 1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
            spierr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/samv7/sam_spi.c

@@ -1864,7 +1864,7 @@ static void spi_exchange(struct spi_dev_s *dev, const void *txbuffer,
 
       ret = wd_start(spics->dmadog, DMA_TIMEOUT_TICKS,
                      (wdentry_t)spi_dmatimeout, 1, (uint32_t)spics);
-      if (ret != OK)
+      if (ret < 0)
         {
            spierr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/samv7/sam_twihs.c

@@ -491,7 +491,8 @@ static int twi_wait(struct twi_dev_s *priv, unsigned int size)
    * TWIHS transfer stalls.
    */
 
-  wd_start(priv->timeout, (timeout * size), twi_timeout, 1, (uint32_t)priv);
+  (void)wd_start(priv->timeout, (timeout * size), twi_timeout, 1,
+                 (uint32_t)priv);
 
   /* Wait for either the TWIHS transfer or the timeout to complete */
 

arch/arm/src/stm32/stm32_sdio.c

@@ -2500,7 +2500,7 @@ static sdio_eventset_t stm32_eventwait(FAR struct sdio_dev_s *dev,
       delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)stm32_eventtimeout,
                        1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
           mcerr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/stm32f7/stm32_sdmmc.c

@@ -2691,7 +2691,7 @@ static sdio_eventset_t stm32_eventwait(FAR struct sdio_dev_s *dev,
       delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)stm32_eventtimeout,
                        1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
           mcerr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/stm32l4/stm32l4_qspi.c

@@ -1447,7 +1447,7 @@ static int qspi_memory_dma(struct stm32l4_qspidev_s *priv,
 
       ret = wd_start(priv->dmadog, DMA_TIMEOUT_TICKS,
                      (wdentry_t)qspi_dma_timeout, 1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
            spierr("ERROR: wd_start failed: %d\n", ret);
         }

arch/arm/src/stm32l4/stm32l4_sdmmc.c

@@ -2637,7 +2637,7 @@ static sdio_eventset_t stm32_eventwait(FAR struct sdio_dev_s *dev,
       delay = MSEC2TICK(timeout);
       ret   = wd_start(priv->waitwdog, delay, (wdentry_t)stm32_eventtimeout,
                        1, (uint32_t)priv);
-      if (ret != OK)
+      if (ret < 0)
         {
           mcerr("ERROR: wd_start failed: %d\n", ret);
         }

arch/mips/src/pic32mx/pic32mx-usbdev.c

@@ -1031,7 +1031,8 @@ static void pic32mx_delayedrestart(struct pic32mx_usbdev_s *priv, uint8_t epno)
 
   /* And start (or re-start) the watchdog timer */
 
-  wd_start(priv->wdog, RESTART_DELAY, pic32mx_rqrestart, 1, (uint32_t)priv);
+  (void)wd_start(priv->wdog, RESTART_DELAY, pic32mx_rqrestart, 1,
+                 (uint32_t)priv);
 }
 
 /****************************************************************************

drivers/input/ads7843e.c

@@ -607,7 +607,8 @@ static void ads7843e_worker(FAR void *arg)
        * later.
        */
 
-       wd_start(priv->wdog, ADS7843E_WDOG_DELAY, ads7843e_wdog, 1, (uint32_t)priv);
+       (void)wd_start(priv->wdog, ADS7843E_WDOG_DELAY, ads7843e_wdog, 1,
+                      (uint32_t)priv);
        goto ignored;
     }
   else

drivers/input/max11802.c

@@ -592,7 +592,7 @@ static void max11802_worker(FAR void *arg)
 
        iinfo("Previous pen up event still in buffer\n");
        max11802_notify(priv);
-       wd_start(priv->wdog, MAX11802_WDOG_DELAY, max11802_wdog, 1,
+       (void)wd_start(priv->wdog, MAX11802_WDOG_DELAY, max11802_wdog, 1,
                       (uint32_t)priv);
        goto ignored;
     }
@@ -632,8 +632,8 @@ static void max11802_worker(FAR void *arg)
 
       /* Continue to sample the position while the pen is down */
 
-      wd_start(priv->wdog, MAX11802_WDOG_DELAY, max11802_wdog, 1,
+      (void)wd_start(priv->wdog, MAX11802_WDOG_DELAY, max11802_wdog, 1,
-               (uint32_t)priv);
+i                    (uint32_t)priv);
 
       /* Check if data is valid */
 

drivers/wireless/ieee80211/bcmf_driver.c

@@ -886,7 +886,7 @@ int bcmf_wl_start_scan(FAR struct bcmf_dev_s *priv, struct iwreq *iwr)
 
   /*  Start scan_timeout timer */
 
-  wd_start(priv->scan_timeout, BCMF_SCAN_TIMEOUT_TICK,
+  (void)wd_start(priv->scan_timeout, BCMF_SCAN_TIMEOUT_TICK,
                  bcmf_wl_scan_timeout, (wdparm_t)priv);
 
   return OK;

drivers/wireless/ieee80211/bcmf_sdio.c

@@ -665,8 +665,8 @@ int bcmf_bus_sdio_initialize(FAR struct bcmf_dev_s *priv,
 
   /* Start the waitdog timer */
 
-  wd_start(sbus->waitdog, BCMF_WAITDOG_TIMEOUT_TICK, bcmf_sdio_waitdog_timeout,
+  (void)wd_start(sbus->waitdog, BCMF_WAITDOG_TIMEOUT_TICK,
-           (wdparm_t)priv);
+                 bcmf_sdio_waitdog_timeout, (wdparm_t)priv);
 
   /* Spawn bcmf daemon thread */
 
@@ -760,7 +760,7 @@ int bcmf_sdio_thread(int argc, char **argv)
 
       /* Restart the waitdog timer */
 
-      wd_start(sbus->waitdog, BCMF_WAITDOG_TIMEOUT_TICK,
+      (void)wd_start(sbus->waitdog, BCMF_WAITDOG_TIMEOUT_TICK,
                      bcmf_sdio_waitdog_timeout, (wdparm_t)priv);
 
       /* Wake up device */

fs/mount/fs_automount.c

@@ -303,11 +303,8 @@ static int automount_unmount(FAR struct automounter_state_s *priv)
                              (uint32_t)((uintptr_t)priv));
               if (ret < 0)
                 {
-                  errcode = get_errno();
+                  ferr("ERROR: wd_start failed: %d\n", ret);
-                  DEBUGASSERT(errcode > 0);
+                  return ret;
-
-                  ferr("ERROR: wd_start failed: %d\n", errcode);
-                  return -ret;
                 }
             }
 

include/nuttx/wdog.h

@@ -1,7 +1,8 @@
 /****************************************************************************
  * include/nuttx/wdog.h
  *
- *   Copyright (C) 2007-2009, 2014-2015 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2014-2015, 2018 Gregory Nutt. All rights
+ *     reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -196,7 +197,8 @@ WDOG_ID wd_create(void);
  *          watchdog structure.
  *
  * Return Value:
- *   Returns OK or ERROR
+ *   Zero (OK) is returned on success; a negated errno value is return to
+ *   indicate the nature of any failure.
  *
  * Assumptions:
  *   The caller has assured that the watchdog is no longer in use.
@@ -230,7 +232,8 @@ int wd_delete(WDOG_ID wdog);
  *   parm1..4 - parameters to pass to wdentry
  *
  * Return Value:
- *   OK or ERROR
+ *   Zero (OK) is returned on success; a negated errno value is return to
+ *   indicate the nature of any failure.
  *
  * Assumptions:
  *   The watchdog routine runs in the context of the timer interrupt handler

sched/mqueue/mq_timedreceive.c

@@ -239,7 +239,7 @@ ssize_t nxmq_timedreceive(mqd_t mqdes, FAR char *msg, size_t msglen,
 
       /* Start the watchdog */
 
-      wd_start(rtcb->waitdog, ticks, (wdentry_t)nxmq_rcvtimeout,
+      (void)wd_start(rtcb->waitdog, ticks, (wdentry_t)nxmq_rcvtimeout,
                      1, getpid());
     }
 

sched/mqueue/mq_timedsend.c

@@ -271,7 +271,8 @@ int nxmq_timedsend(mqd_t mqdes, FAR const char *msg, size_t msglen, int prio,
 
   /* Start the watchdog and begin the wait for MQ not full */
 
-  wd_start(rtcb->waitdog, ticks, (wdentry_t)nxmq_sndtimeout, 1, getpid());
+  (void)wd_start(rtcb->waitdog, ticks, (wdentry_t)nxmq_sndtimeout,
+                 1, getpid());
 
   /* And wait for the message queue to be non-empty */
 

sched/pthread/pthread_condtimedwait.c

@@ -274,8 +274,10 @@ int pthread_cond_timedwait(FAR pthread_cond_t *cond, FAR pthread_mutex_t *mutex,
                     {
                       /* Start the watchdog */
 
-                      wd_start(rtcb->waitdog, ticks, (wdentry_t)pthread_condtimedout,
+                      (void)wd_start(rtcb->waitdog, ticks,
-                               2, (uint32_t)mypid, (uint32_t)SIGCONDTIMEDOUT);
+                                     (wdentry_t)pthread_condtimedout,
+                                     2, (uint32_t)mypid,
+                                     (uint32_t)SIGCONDTIMEDOUT);
 
                       /* Take the condition semaphore.  Do not restore interrupts
                        * until we return from the wait.  This is necessary to

sched/signal/sig_timedwait.c

@@ -356,8 +356,8 @@ int nxsig_timedwait(FAR const sigset_t *set, FAR struct siginfo *info,
 
               /* Start the watchdog */
 
-              wd_start(rtcb->waitdog, waitticks, (wdentry_t)nxsig_timeout,
+              (void)wd_start(rtcb->waitdog, waitticks,
-                       1, wdparm.pvarg);
+                             (wdentry_t)nxsig_timeout, 1, wdparm.pvarg);
 
               /* Now wait for either the signal or the watchdog */
 

sched/timer/timer_settime.c

@@ -1,7 +1,8 @@
 /****************************************************************************
  * sched/timer/timer_settime.c
  *
- *   Copyright (C) 2007-2010, 2013-2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2010, 2013-2016, 2018 Gregory Nutt. All rights
+ *     reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -390,6 +391,15 @@ int timer_settime(timer_t timerid, int flags,
       timer->pt_last = delay;
       ret = wd_start(timer->pt_wdog, delay, (wdentry_t)timer_timeout,
                      1, (uint32_t)((wdparm_t)timer));
+      if (ret < 0)
+        {
+          set_errno(-ret);
+          ret = ERROR;
+        }
+      else
+        {
+          ret = OK;
+        }
     }
 
   leave_critical_section(intflags);

sched/wdog/wd_delete.c

@@ -68,7 +68,8 @@
  *          watchdog structure.
  *
  * Return Value:
- *   Returns OK or ERROR
+ *   Zero (OK) is returned on success; a negated errno value is return to
+ *   indicate the nature of any failure.
  *
  * Assumptions:
  *   The caller has assured that the watchdog is no longer in use.

sched/wdog/wd_start.c

@@ -1,7 +1,8 @@
 /****************************************************************************
  * sched/wdog/wd_start.c
  *
- *   Copyright (C) 2007-2009, 2012, 2014, 2016 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2012, 2014, 2016, 2018 Gregory Nutt.  All
+ *     rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -103,8 +104,6 @@ typedef void (*wdentry4_t)(int argc, wdparm_t arg1, wdparm_t arg2,
  * Return Value:
  *   None
  *
- * Assumptions:
- *
  ****************************************************************************/
 
 static inline void wd_expiration(void)
@@ -211,7 +210,8 @@ static inline void wd_expiration(void)
  *   parm1..4 - parameters to pass to wdentry
  *
  * Return Value:
- *   OK or ERROR
+ *   Zero (OK) is returned on success; a negated errno value is return to
+ *   indicate the nature of any failure.
  *
  * Assumptions:
  *   The watchdog routine runs in the context of the timer interrupt handler
@@ -229,12 +229,11 @@ int wd_start(WDOG_ID wdog, int32_t delay, wdentry_t wdentry,  int argc, ...)
   irqstate_t flags;
   int i;
 
-  /* Verify the wdog */
+  /* Verify the wdog and setup parameters */
 
-  if (!wdog || argc > CONFIG_MAX_WDOGPARMS || delay < 0)
+  if (wdog == NULL || argc > CONFIG_MAX_WDOGPARMS || delay < 0)
     {
-      set_errno(EINVAL);
+      return -EINVAL;
-      return ERROR;
     }
 
   /* Check if the watchdog has been started. If so, stop it.