Add pthread_mutexattr_get/set_protocol and non-standard sem_get/set_protocol. These may use to enable or disable priority inheritance on a single semaphore.

include/nuttx/semaphore.h

@@ -61,12 +61,13 @@
 struct inode;
 struct nsem_inode_s
 {
+  sem_t ns_sem;                     /* The contained semaphore */
+
   /* Inode payload unique to named semaphores.  ns_inode must appear first
    * in this structure in order to support casting between type sem_t and
    * types of struct nsem_inode_s. */
 
   FAR struct inode *ns_inode;       /* Containing inode */
-  sem_t ns_sem;                     /* The semaphore */
 };
 #endif
 

include/pthread.h

@@ -135,6 +135,12 @@
 
 #define PTHREAD_BARRIER_SERIAL_THREAD 0x1000
 
+/* Values for protocol attribute */
+
+#define PTHREAD_PRIO_NONE             SEM_PRIO_NONE
+#define PTHREAD_PRIO_INHERIT          SEM_PRIO_INHERIT
+#define PTHREAD_PRIO_PROTECT          SEM_PRIO_PROTECT
+
 /* Definitions to map some non-standard, BSD thread management interfaces to
  * the non-standard Linux-like prctl() interface.  Since these are simple
  * mappings to prctl, they will return 0 on success and -1 on failure with the
@@ -212,6 +218,9 @@ typedef struct pthread_cond_s pthread_cond_t;
 struct pthread_mutexattr_s
 {
   uint8_t pshared;  /* PTHREAD_PROCESS_PRIVATE or PTHREAD_PROCESS_SHARED */
+#ifdef CONFIG_PRIORITY_INHERITANCE
+  uint8_t proto;    /* See PTHREAD_PRIO_* definitions */
+#endif
 #ifdef CONFIG_MUTEX_TYPES
   uint8_t type;     /* Type of the mutex.  See PTHREAD_MUTEX_* definitions */
 #endif
@@ -395,6 +404,15 @@ int pthread_mutex_lock(FAR pthread_mutex_t *mutex);
 int pthread_mutex_trylock(FAR pthread_mutex_t *mutex);
 int pthread_mutex_unlock(FAR pthread_mutex_t *mutex);
 
+#ifdef CONFIG_PRIORITY_INHERITANCE
+/* Manage priority inheritance */
+
+int pthread_mutexattr_getprotocol(FAR const pthread_mutexattr_t *attr,
+                                  FAR int *protocol);
+int pthread_mutexattr_setprotocol(FAR pthread_mutexattr_t *attr,
+                                  int protocol);
+#endif
+
 /* Operations on condition variables */
 
 int pthread_condattr_init(FAR pthread_condattr_t *attr);

include/semaphore.h

@@ -57,6 +57,17 @@ extern "C"
  * Pre-processor Definitions
  ****************************************************************************/
 
+/* Values for protocol attribute */
+
+#define SEM_PRIO_NONE             0
+#define SEM_PRIO_INHERIT          1
+#define SEM_PRIO_PROTECT          2
+
+/* Bit definitions for the struct sem_s flags field */
+
+#define PRIOINHERIT_FLAGS_DISABLE (1 << 0)  /* Bit 0: Priority inheritance
+                                             * is disabled for this semaphore. */
+
 /****************************************************************************
  * Public Type Declarations
  ****************************************************************************/
@@ -92,6 +103,7 @@ struct sem_s
    */
 
 #ifdef CONFIG_PRIORITY_INHERITANCE
+  uint8_t flags;                 /* See PRIOINHERIT_FLAGS_* definitions */
 # if CONFIG_SEM_PREALLOCHOLDERS > 0
   FAR struct semholder_s *hhead; /* List of holders of semaphore counts */
 # else
@@ -106,9 +118,9 @@ typedef struct sem_s sem_t;
 
 #ifdef CONFIG_PRIORITY_INHERITANCE
 # if CONFIG_SEM_PREALLOCHOLDERS > 0
-#  define SEM_INITIALIZER(c) {(c), NULL}  /* semcount, hhead */
+#  define SEM_INITIALIZER(c) {(c), 0, NULL}  /* semcount, flags, hhead */
 # else
-#  define SEM_INITIALIZER(c) {(c), SEMHOLDER_INITIALIZER} /* semcount, holder */
+#  define SEM_INITIALIZER(c) {(c), 0, SEMHOLDER_INITIALIZER} /* semcount, flags, holder */
 # endif
 #else
 #  define SEM_INITIALIZER(c) {(c)} /* semcount */
@@ -141,6 +153,13 @@ int        sem_close(FAR sem_t *sem);
 int        sem_unlink(FAR const char *name);
 #endif
 
+#ifdef CONFIG_PRIORITY_INHERITANCE
+/* Non-standard interfaces to manage priority inheritance */
+
+int        sem_getprotocol(FAR sem_t *sem, FAR int *protocol);
+int        sem_setprotocol(FAR sem_t *sem, int protocol);
+#endif
+
 #undef EXTERN
 #ifdef __cplusplus
 }

include/sys/syscall.h

@@ -91,15 +91,23 @@
 #define SYS_sem_trywait                (CONFIG_SYS_RESERVED+18)
 #define SYS_sem_wait                   (CONFIG_SYS_RESERVED+19)
 
+#ifdef CONFIG_PRIORITY_INHERITANCE
+#  define SYS_sem_getprotocol          (CONFIG_SYS_RESERVED+20)
+#  define SYS_sem_setprotocol          (CONFIG_SYS_RESERVED+21)
+#  define __SYS_named_sem              (CONFIG_SYS_RESERVED+22)
+#else
+#  define __SYS_named_sem              (CONFIG_SYS_RESERVED+20)
+#endif
+
 /* Named semaphores */
 
 #ifdef CONFIG_FS_NAMED_SEMAPHORES
-#  define SYS_sem_open                 (CONFIG_SYS_RESERVED+20)
-#  define SYS_sem_close                (CONFIG_SYS_RESERVED+21)
-#  define SYS_sem_unlink               (CONFIG_SYS_RESERVED+22)
-#  define __SYS_task_create            (CONFIG_SYS_RESERVED+23)
+#  define SYS_sem_open                 __SYS_named_sem
+#  define SYS_sem_close                (__SYS_named_sem+1)
+#  define SYS_sem_unlink               (__SYS_named_sem+2)
+#  define __SYS_task_create            (__SYS_named_sem+3)
 #else
-#  define __SYS_task_create            (CONFIG_SYS_RESERVED+20)
+#  define __SYS_task_create            __SYS_named_sem
 #endif
 
 /* Task creation APIs based on global entry points cannot be use with

libc/pthread/Make.defs

@@ -54,6 +54,10 @@ ifeq ($(CONFIG_MUTEX_TYPES),y)
 CSRCS += pthread_mutexattr_settype.c pthread_mutexattr_gettype.c
 endif
 
+ifeq ($(CONFIG_PRIORITY_INHERITANCE),y)
+CSRCS += pthread_mutexattr_setprotocol.c pthread_mutexattr_getprotocol.c
+endif
+
 ifeq ($(CONFIG_BUILD_PROTECTED),y)
 CSRCS += pthread_startup.c
 endif

libc/pthread/pthread_attr_destroy.c

@@ -52,8 +52,7 @@
  * Function:  pthread_attr_destroy
  *
  * Description:
- *    An attributes object can be deleted when it is no longer
- *     needed.
+ *    An attributes object can be deleted when it is no longer needed.
  *
  * Parameters:
  *   attr

libc/pthread/pthread_mutexattr_destroy.c

@@ -55,7 +55,6 @@
  *
  * Parameters:
  *    attr
- *    pshared
  *
  * Return Value:
  *   0 if successful.  Otherwise, an error code.

libc/pthread/pthread_mutexattr_getprotocol.c

@@ -0,0 +1,73 @@
+/****************************************************************************
+ * libc/pthread/pthread_mutexattr_getprotocol.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <pthread.h>
+#include <assert.h>
+#include <debug.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function: pthread_mutexattr_getprotocol
+ *
+ * Description:
+ *    Return the value of the mutex protocol attribute.
+ *
+ * Parameters:
+ *    attr     - A pointer to the mutex attributes to be queried.
+ *    protocol - The user provided location in which to store the protocol
+ *               value.
+ *
+ * Return Value:
+ *   0 if successful.  Otherwise, an error code.
+ *
+ ****************************************************************************/
+
+int pthread_mutexattr_getprotocol(FAR const pthread_mutexattr_t *attr,
+                                  FAR int *protocol)
+{
+  DEBUGASSERT(attr != NULL && protocol != NULL);
+
+  linfo("Returning %d\n", attr->proto);
+  return attr->proto;
+}

libc/pthread/pthread_mutexattr_setprotocol.c

@@ -0,0 +1,79 @@
+/****************************************************************************
+ * libc/pthread/pthread_mutexattr_setprotocol.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <pthread.h>
+#include <assert.h>
+#include <errno.h>
+#include <debug.h>
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function: pthread_mutexattr_setprotocol
+ *
+ * Description:
+ *    Set mutex protocol attribute.
+ *
+ * Parameters:
+ *    attr     - A pointer to the mutex attributes to be modified
+ *    protocol - The new protocol to use
+ *
+ * Return Value:
+ *   0 if successful.  Otherwise, an error code.
+ *
+ ****************************************************************************/
+
+int pthread_mutexattr_setprotocol(FAR pthread_mutexattr_t *attr,
+                                  int protocol)
+{
+  linfo("attr=0x%p protocol=%d\n", attr, protocol);
+  DEBUGASSERT(attr != NULL);
+
+  if (protocol >= PTHREAD_PRIO_NONE && protocol <= PTHREAD_PRIO_PROTECT)
+    {
+      attr->proto = protocol;
+      return OK;
+    }
+
+  return EINVAL;
+}

libc/semaphore/sem_init.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * libc/sem/sem_init.c
  *
- *   Copyright (C) 2007-2009, 2011-2012 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011-2012, 2016 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -44,26 +44,6 @@
 #include <semaphore.h>
 #include <errno.h>
 
-/****************************************************************************
- * Pre-processor Definitions
- ****************************************************************************/
-
-/****************************************************************************
- * Private Type Declarations
- ****************************************************************************/
-
-/****************************************************************************
- * Public Data
- ****************************************************************************/
-
-/****************************************************************************
- * Private Data
- ****************************************************************************/
-
-/****************************************************************************
- * Private Functions
- ****************************************************************************/
-
 /****************************************************************************
  * Public Functions
  ****************************************************************************/
@@ -108,6 +88,7 @@ int sem_init(FAR sem_t *sem, int pshared, unsigned int value)
       /* Initialize to support priority inheritance */
 
 #ifdef CONFIG_PRIORITY_INHERITANCE
+      sem->flags         = 0;
 #  if CONFIG_SEM_PREALLOCHOLDERS > 0
       sem->hhead         = NULL;
 #  else

sched/pthread/pthread_mutexinit.c

@@ -1,7 +1,7 @@
 /****************************************************************************
  * sched/pthread/pthread_mutexinit.c
  *
- *   Copyright (C) 2007-2009, 2011 Gregory Nutt. All rights reserved.
+ *   Copyright (C) 2007-2009, 2011, 2016 Gregory Nutt. All rights reserved.
  *   Author: Gregory Nutt <gnutt@nuttx.org>
  *
  * Redistribution and use in source and binary forms, with or without
@@ -66,11 +66,15 @@
  *
  ****************************************************************************/
 
-int pthread_mutex_init(FAR pthread_mutex_t *mutex, FAR const pthread_mutexattr_t *attr)
+int pthread_mutex_init(FAR pthread_mutex_t *mutex,
+                       FAR const pthread_mutexattr_t *attr)
 {
   int pshared = 0;
 #ifdef CONFIG_MUTEX_TYPES
   uint8_t type = PTHREAD_MUTEX_DEFAULT;
+#endif
+#ifdef CONFIG_PRIORITY_INHERITANCE
+  uint8_t proto = PTHREAD_PRIO_INHERIT;
 #endif
   int ret = OK;
   int status;
@@ -88,6 +92,9 @@ int pthread_mutex_init(FAR pthread_mutex_t *mutex, FAR const pthread_mutexattr_t
       if (attr)
         {
           pshared = attr->pshared;
+#ifdef CONFIG_PRIORITY_INHERITANCE
+          proto   = attr->proto;
+#endif
 #ifdef CONFIG_MUTEX_TYPES
           type    = attr->type;
 #endif
@@ -102,9 +109,19 @@ int pthread_mutex_init(FAR pthread_mutex_t *mutex, FAR const pthread_mutexattr_t
       status = sem_init((FAR sem_t *)&mutex->sem, pshared, 1);
       if (status != OK)
         {
-          ret = EINVAL;
+          ret = get_errno();
         }
 
+#ifdef CONFIG_PRIORITY_INHERITANCE
+      /* Initialize the semaphore protocol */
+
+      status = sem_setprotocol((FAR sem_t *)&mutex->sem, proto);
+      if (status != OK)
+        {
+          ret = get_errno();
+        }
+#endif
+
       /* Set up attributes unique to the mutex type */
 
 #ifdef CONFIG_MUTEX_TYPES

sched/semaphore/Make.defs

@@ -33,12 +33,15 @@
 #
 ############################################################################
 
+# Add semaphore-related files to the build
+
 CSRCS += sem_destroy.c sem_wait.c sem_trywait.c sem_tickwait.c
 CSRCS += sem_timedwait.c sem_timeout.c sem_post.c sem_recover.c
 CSRCS += sem_reset.c sem_waitirq.c
 
 ifeq ($(CONFIG_PRIORITY_INHERITANCE),y)
 CSRCS += sem_initialize.c sem_holder.c
+CSRCS += sem_setprotocol.c sem_getprotocol.c
 endif
 
 ifeq ($(CONFIG_SPINLOCK),y)

sched/semaphore/sem_getprotocol.c

@@ -0,0 +1,85 @@
+/****************************************************************************
+ * sched/semaphore/sem_getprotocol.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <semaphore.h>
+#include <assert.h>
+
+#include "semaphore/semaphore.h"
+
+#ifdef CONFIG_PRIORITY_INHERITANCE
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function: sem_getprotocol
+ *
+ * Description:
+ *    Return the value of the semaphore protocol attribute.
+ *
+ * Parameters:
+ *    sem      - A pointer to the semaphore whose attributes are to be
+ *               queried.
+ *    protocol - The user provided location in which to store the protocol
+ *               value.
+ *
+ * Return Value:
+ *   0 if successful.  Otherwise, -1 is returned and the errno value is set
+ *   appropriately.
+ *
+ ****************************************************************************/
+
+int sem_getprotocol(FAR sem_t *sem, FAR int *protocol)
+{
+  DEBUGASSERT(sem != NULL);
+
+  if ((sem->flags & PRIOINHERIT_FLAGS_DISABLE) != 0)
+    {
+      return SEM_PRIO_NONE;
+    }
+  else
+    {
+      return SEM_PRIO_INHERIT;
+    }
+}
+
+#endif /* CONFIG_PRIORITY_INHERITANCE */

sched/semaphore/sem_holder.c

@@ -790,7 +790,7 @@ void sem_initholders(void)
  * Name: sem_destroyholder
  *
  * Description:
- *   Called from sem_destroy() to handle any holders of a semaphore when
+ *   Called from sem_destroyholder() to handle any holders of a semaphore when
  *   it is destroyed.
  *
  * Parameters:
@@ -855,6 +855,13 @@ void sem_addholder_tcb(FAR struct tcb_s *htcb, FAR sem_t *sem)
 {
   FAR struct semholder_s *pholder;
 
+  /* If priority inheritance is disabled for this thread, then do not add
+   * the holder.  If there are never holders of the semaphore, the priority
+   * inheritance is effectively disabled.
+   */
+
+  if ((sem->flags & PRIOINHERIT_FLAGS_DISABLE) == 0)
+    {
       /* Find or allocate a container for this new holder */
 
       pholder = sem_findorallocateholder(sem, htcb);
@@ -867,6 +874,7 @@ void sem_addholder_tcb(FAR struct tcb_s *htcb, FAR sem_t *sem)
           pholder->htcb = htcb;
           pholder->counts++;
         }
+    }
 }
 
 /****************************************************************************

sched/semaphore/sem_setprotocol.c

@@ -0,0 +1,110 @@
+/****************************************************************************
+ * sched/semaphore/sem_setprotocol.c
+ *
+ *   Copyright (C) 2016 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <semaphore.h>
+#include <assert.h>
+#include <errno.h>
+
+#include "semaphore/semaphore.h"
+
+#ifdef CONFIG_PRIORITY_INHERITANCE
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function: sem_setprotocol
+ *
+ * Description:
+ *    Set semaphore protocol attribute.
+ *
+ * Parameters:
+ *    sem      - A pointer to the semaphore whose attributes are to be
+ *               modified
+ *    protocol - The new protocol to use
+ *
+ * Return Value:
+ *   0 if successful.  Otherwise, -1 is returned and the errno value is set
+ *   appropriately.
+ *
+ ****************************************************************************/
+
+int sem_setprotocol(FAR sem_t *sem, int protocol)
+{
+  int errcode;
+
+  DEBUGASSERT(sem != NULL);
+
+  switch (protocol)
+    {
+      case SEM_PRIO_NONE:
+        /* Disable priority inheritance */
+
+        sem->flags |= PRIOINHERIT_FLAGS_DISABLE;
+
+        /* Remove any current holders */
+
+        sem_destroyholder(sem);
+        return OK;
+
+      case SEM_PRIO_INHERIT:
+        /* Enable priority inheritance (dangerous) */
+
+        sem->flags &= ~PRIOINHERIT_FLAGS_DISABLE;
+        return OK;
+
+      case SEM_PRIO_PROTECT:
+        /* Not yet supported */
+
+        errcode = ENOSYS;
+        break;
+
+      default:
+        errcode = EINVAL;
+        break;
+    }
+
+  set_errno(errcode);
+  return ERROR;
+}
+
+#endif /* CONFIG_PRIORITY_INHERITANCE */

syscall/syscall.csv

@@ -117,7 +117,9 @@
 "sem_close","semaphore.h","defined(CONFIG_FS_NAMED_SEMAPHORES)","int","FAR sem_t*"
 "sem_destroy","semaphore.h","","int","FAR sem_t*"
 "sem_open","semaphore.h","defined(CONFIG_FS_NAMED_SEMAPHORES)","FAR sem_t*","FAR const char*","int","..."
+"sem_getprotocol","semaphore.h","defined(CONFIG_PRIORITY_INHERITANCE)","int","FAR sem_t*","FAR int*"
 "sem_post","semaphore.h","","int","FAR sem_t*"
+"sem_setprotocol","semaphore.h","defined(CONFIG_PRIORITY_INHERITANCE)","int","FAR sem_t*","int"
 "sem_timedwait","semaphore.h","","int","FAR sem_t*","FAR const struct timespec *"
 "sem_trywait","semaphore.h","","int","FAR sem_t*"
 "sem_unlink","semaphore.h","defined(CONFIG_FS_NAMED_SEMAPHORES)","int","FAR const char*"

syscall/syscall_lookup.h

@@ -61,12 +61,17 @@ SYSCALL_LOOKUP(uname,                     1, STUB_uname)
 
 /* Semaphores */
 
-SYSCALL_LOOKUP(sem_destroy,               2, STUB_sem_destroy)
+SYSCALL_LOOKUP(sem_destroy,               1, STUB_sem_destroy)
 SYSCALL_LOOKUP(sem_post,                  1, STUB_sem_post)
 SYSCALL_LOOKUP(sem_timedwait,             2, STUB_sem_timedwait)
 SYSCALL_LOOKUP(sem_trywait,               1, STUB_sem_trywait)
 SYSCALL_LOOKUP(sem_wait,                  1, STUB_sem_wait)
 
+#ifdef CONFIG_PRIORITY_INHERITANCE
+SYSCALL_LOOKUP(sem_getprotocol,           2, STUB_sem_getprotocol)
+SYSCALL_LOOKUP(sem_setprotocol,           2, STUB_sem_setprotocol)
+#endif
+
 /* Named semaphores */
 
 #ifdef CONFIG_FS_NAMED_SEMAPHORES

syscall/syscall_stublookup.c

@@ -82,13 +82,16 @@ uintptr_t STUB_uname(int nbr, uintptr_t parm1);
 
 uintptr_t STUB_sem_close(int nbr, uintptr_t parm1);
 uintptr_t STUB_sem_destroy(int nbr, uintptr_t parm1);
+uintptr_t STUB_sem_getprotocol(int nbr, uintptr_t parm1, uintptr_t parm2);
 uintptr_t STUB_sem_open(int nbr, uintptr_t parm1, uintptr_t parm2,
             uintptr_t parm3, uintptr_t parm4, uintptr_t parm5, uintptr_t parm6);
 uintptr_t STUB_sem_post(int nbr, uintptr_t parm1);
+uintptr_t STUB_sem_setprotocol(int nbr, uintptr_t parm1, uintptr_t parm2);
 uintptr_t STUB_sem_timedwait(int nbr, uintptr_t parm1, uintptr_t parm2);
 uintptr_t STUB_sem_trywait(int nbr, uintptr_t parm1);
 uintptr_t STUB_sem_unlink(int nbr, uintptr_t parm1);
 uintptr_t STUB_sem_wait(int nbr, uintptr_t parm1);
+
 uintptr_t STUB_pgalloc(int nbr, uintptr_t parm1, uintptr_t parm2);
 uintptr_t STUB_task_create(int nbr, uintptr_t parm1, uintptr_t parm2,
             uintptr_t parm3, uintptr_t parm4, uintptr_t parm5);