From 0109bcad8c61a19cf19a43f39cdfff7bedfa78e1 Mon Sep 17 00:00:00 2001
From: Gustavo Henrique Nihei <gustavo.nihei@espressif.com>
Date: Tue, 30 Mar 2021 14:04:27 -0300
Subject: [PATCH] libs/libc: Update pthread_once according to the specification

OpenGroup specification was updated regarding the return value for
pthread_once, which after Issue 7 states that "the [EINVAL] error for an
uninitialized pthread_once_t object is removed; this condition results
in undefined behavior".
---
 libs/libc/pthread/pthread_once.c | 45 +++++++++++++++-----------------
 1 file changed, 21 insertions(+), 24 deletions(-)

diff --git a/libs/libc/pthread/pthread_once.c b/libs/libc/pthread/pthread_once.c
index c662f15de8..0e6060a008 100644
--- a/libs/libc/pthread/pthread_once.c
+++ b/libs/libc/pthread/pthread_once.c
@@ -24,10 +24,10 @@
 
 #include <nuttx/config.h>
 
+#include <assert.h>
 #include <stdbool.h>
 #include <pthread.h>
 #include <sched.h>
-#include <errno.h>
 #include <debug.h>
 
 /****************************************************************************
@@ -38,14 +38,14 @@
  * Name: pthread_once
  *
  * Description:
- *   The  first call to pthread_once() by any thread with a given
+ *   The first call to pthread_once() by any thread with a given
  *   once_control, will call the init_routine with no arguments. Subsequent
  *   calls to pthread_once() with the same once_control will have no effect.
  *   On return from pthread_once(), init_routine will have completed.
  *
  * Input Parameters:
  *   once_control - Determines if init_routine should be called.
- *     once_control should be declared and initializeed as follows:
+ *     once_control should be declared and initialized as follows:
  *
  *        pthread_once_t once_control = PTHREAD_ONCE_INIT;
  *
@@ -53,8 +53,8 @@
  *   init_routine - The initialization routine that will be called once.
  *
  * Returned Value:
- *   0 (OK) on success or EINVAL if either once_control or init_routine are
- *   invalid
+ *   0 (OK) on success or an error number shall be returned to
+ *   indicate the error.
  *
  * Assumptions:
  *
@@ -65,31 +65,28 @@ int pthread_once(FAR pthread_once_t *once_control,
 {
   /* Sanity checks */
 
-  if (once_control && init_routine)
+  DEBUGASSERT(once_control != NULL);
+  DEBUGASSERT(init_routine != NULL);
+
+  /* Prohibit pre-emption while we test and set the once_control. */
+
+  sched_lock();
+
+  if (!*once_control)
     {
-      /* Prohibit pre-emption while we test and set the once_control */
+      *once_control = true;
 
-      sched_lock();
-      if (!*once_control)
-        {
-          *once_control = true;
-
-          /* Call the init_routine with pre-emption enabled. */
-
-          sched_unlock();
-          init_routine();
-          return OK;
-        }
-
-      /* The init_routine has already been called.
-       * Restore pre-emption and return
-       */
+      /* Call the init_routine with pre-emption enabled. */
 
       sched_unlock();
+      init_routine();
       return OK;
     }
 
-  /* One of the two arguments is NULL */
+  /* The init_routine has already been called.
+   * Restore pre-emption and return.
+   */
 
-  return EINVAL;
+  sched_unlock();
+  return OK;
 }