sem: Remove PRIOINHERIT_FLAGS_ENABLE and use SEM_PRIO_INHERIT instead

and refine the code to prepare the support of new flags

Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>

include/nuttx/mutex.h

@@ -37,8 +37,8 @@
  ****************************************************************************/
 
 #define NXRMUTEX_NO_HOLDER   (pid_t)-1
-#define NXMUTEX_INITIALIZER  NXSEM_INITIALIZER(1, PRIOINHERIT_FLAGS_ENABLE)
+#define NXMUTEX_INITIALIZER  NXSEM_INITIALIZER(1, SEM_PRIO_INHERIT)
-#define NXRMUTEX_INITIALIZER {NXSEM_INITIALIZER(1, PRIOINHERIT_FLAGS_ENABLE), \
+#define NXRMUTEX_INITIALIZER {NXSEM_INITIALIZER(1, SEM_PRIO_INHERIT), \
                               NXRMUTEX_NO_HOLDER, 0}
 
 /****************************************************************************

include/semaphore.h

@@ -41,17 +41,12 @@
 #define SEM_PRIO_NONE             0
 #define SEM_PRIO_INHERIT          1
 #define SEM_PRIO_PROTECT          2
+#define SEM_PRIO_MASK             3
 
 /* Value returned by sem_open() in the event of a failure. */
 
 #define SEM_FAILED                NULL
 
-/* Bit definitions for the struct sem_s flags field */
-
-#define PRIOINHERIT_FLAGS_ENABLE (1 << 0)  /* Bit 0: Priority inheritance
-                                            * is enabled for this semaphore.
-                                            */
-
 /****************************************************************************
  * Public Type Declarations
  ****************************************************************************/

libs/libc/semaphore/sem_getprotocol.c

@@ -55,15 +55,7 @@ int sem_getprotocol(FAR sem_t *sem, FAR int *protocol)
   DEBUGASSERT(sem != NULL && protocol != NULL);
 
 #ifdef CONFIG_PRIORITY_INHERITANCE
-  if ((sem->flags & PRIOINHERIT_FLAGS_ENABLE) != 0)
+  *protocol = sem->flags;
-    {
-      *protocol = SEM_PRIO_INHERIT;
-    }
-  else
-    {
-      *protocol = SEM_PRIO_NONE;
-    }
-
 #else
   *protocol = SEM_PRIO_NONE;
 #endif

sched/semaphore/sem_holder.c

@@ -700,6 +700,7 @@ void nxsem_destroyholder(FAR sem_t *sem)
 void nxsem_add_holder_tcb(FAR struct tcb_s *htcb, FAR sem_t *sem)
 {
   FAR struct semholder_s *pholder;
+  uint8_t prioinherit = sem->flags & SEM_PRIO_MASK;
 
   /* If priority inheritance is disabled for this thread or it is IDLE
    * thread, then do not add the holder.
@@ -707,7 +708,7 @@ void nxsem_add_holder_tcb(FAR struct tcb_s *htcb, FAR sem_t *sem)
    * inheritance is effectively disabled.
    */
 
-  if (!is_idle_task(htcb) && (sem->flags & PRIOINHERIT_FLAGS_ENABLE) != 0)
+  if (!is_idle_task(htcb) && prioinherit == SEM_PRIO_INHERIT)
     {
       /* Find or allocate a container for this new holder */
 

sched/semaphore/sem_post.c

@@ -121,8 +121,8 @@ int nxsem_post(FAR sem_t *sem)
    * will do nothing.
    */
 
-  prioinherit = sem->flags & PRIOINHERIT_FLAGS_ENABLE;
+  prioinherit = sem->flags & SEM_PRIO_MASK;
-  if (prioinherit != 0)
+  if (prioinherit == SEM_PRIO_INHERIT)
     {
       sched_lock();
     }
@@ -188,7 +188,7 @@ int nxsem_post(FAR sem_t *sem)
    */
 
 #ifdef CONFIG_PRIORITY_INHERITANCE
-  if (prioinherit != 0)
+  if (prioinherit == SEM_PRIO_INHERIT)
     {
       nxsem_restore_baseprio(stcb, sem);
       sched_unlock();

sched/semaphore/sem_setprotocol.c

@@ -76,25 +76,18 @@ int nxsem_set_protocol(FAR sem_t *sem, int protocol)
 {
   DEBUGASSERT(sem != NULL);
 
-  switch (protocol)
+  switch (protocol & SEM_PRIO_MASK)
     {
       case SEM_PRIO_NONE:
 
-        /* Disable priority inheritance */
-
-        sem->flags &= ~PRIOINHERIT_FLAGS_ENABLE;
-
         /* Remove any current holders */
 
         nxsem_destroyholder(sem);
-        return OK;
+        break;
 
       case SEM_PRIO_INHERIT:
 
-        /* Enable priority inheritance (dangerous) */
+        break;
-
-        sem->flags |= PRIOINHERIT_FLAGS_ENABLE;
-        return OK;
 
       case SEM_PRIO_PROTECT:
 
@@ -103,10 +96,11 @@ int nxsem_set_protocol(FAR sem_t *sem, int protocol)
         return -ENOTSUP;
 
       default:
-        break;
+        return -EINVAL;
     }
 
-  return -EINVAL;
+  sem->flags = protocol;
+  return OK;
 }
 
 /****************************************************************************

sched/semaphore/sem_wait.c

@@ -108,7 +108,7 @@ int nxsem_wait(FAR sem_t *sem)
   else
     {
 #ifdef CONFIG_PRIORITY_INHERITANCE
-      uint8_t prioinherit = sem->flags & PRIOINHERIT_FLAGS_ENABLE;
+      uint8_t prioinherit = sem->flags & SEM_PRIO_MASK;
 #endif
 
       /* First, verify that the task is not already waiting on a
@@ -130,7 +130,7 @@ int nxsem_wait(FAR sem_t *sem)
        */
 
 #ifdef CONFIG_PRIORITY_INHERITANCE
-      if (prioinherit != 0)
+      if (prioinherit == SEM_PRIO_INHERIT)
         {
           /* Disable context switching.  The following operations must be
            * atomic with regard to the scheduler.