sched/semaphore: add support to customize semaphore max allowed value

Curernt implementation default semaphore max allowed value to SEM_VALUE_MAX.
  In some cases, user may want to change this, so provide a function to do this: sem_setmaxvalue

Signed-off-by: Chengdong Wang <wangchengdong@lixiang.com>

libs/libc/semaphore/CMakeLists.txt

@@ -36,6 +36,10 @@ if(CONFIG_FS_NAMED_SEMAPHORES)
   list(APPEND SRCS sem_open.c sem_close.c sem_unlink.c)
 endif()
 
+if(CONFIG_CUSTOM_SEMAPHORE_MAXVALUE)
+  list(APPEND SRCS sem_setmaxvalue.c)
+endif()
+
 if(CONFIG_PRIORITY_PROTECT)
   list(APPEND SRCS sem_getprioceiling.c sem_setprioceiling.c)
 endif()

libs/libc/semaphore/Make.defs

@@ -30,6 +30,10 @@ ifeq ($(CONFIG_FS_NAMED_SEMAPHORES),y)
 CSRCS += sem_open.c sem_close.c sem_unlink.c
 endif
 
+ifeq ($(CONFIG_CUSTOM_SEMAPHORE_MAXVALUE),y)
+CSRCS += sem_setmaxvalue.c
+endif
+
 ifeq ($(CONFIG_PRIORITY_PROTECT),y)
 CSRCS += sem_getprioceiling.c sem_setprioceiling.c
 endif

libs/libc/semaphore/sem_init.c

@@ -72,6 +72,10 @@ int nxsem_init(FAR sem_t *sem, int pshared, int32_t value)
 
   sem->val.semcount = (int32_t)value;
 
+#ifdef CONFIG_CUSTOM_SEMAPHORE_MAXVALUE
+  sem->maxvalue = SEM_VALUE_MAX;
+#endif
+
   /* Initialize semaphore wait list */
 
   dq_init(&sem->waitlist);

libs/libc/semaphore/sem_setmaxvalue.c

@@ -0,0 +1,66 @@
+/****************************************************************************
+ * libs/libc/semaphore/sem_setmaxvalue.c
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.  The
+ * ASF licenses this file to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the
+ * License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/trace.h>
+
+#include <nuttx/semaphore.h>
+
+#ifdef CONFIG_CUSTOM_SEMAPHORE_MAXVALUE
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: nxsem_setmaxvalue
+ *
+ * Description:
+ *  Set sem max allowed value
+ *
+ * Input Parameters:
+ *   sem     - Semaphore object
+ *   delay   - Max allowed semaphore value.
+ *
+ * Returned Value:
+ *   This is an internal OS interface and should not be used by applications.
+ *   It follows the NuttX internal error return policy:  Zero (OK) is
+ *   returned on success.  A negated errno value is returned on failure.
+ *
+ ****************************************************************************/
+
+int nxsem_setmaxvalue(FAR sem_t *sem, int32_t maxvalue)
+{
+  if (sem != NULL)
+    {
+      sem->maxvalue = maxvalue;
+      return OK;
+    }
+
+  return -EINVAL;
+}
+
+#endif /* CONFIG_PRIORITY_INHERITANCE */