/**************************************************************************** * nuttx/graphics/nxterm/nxterm_sem.c * * Copyright (C) 2012, 2017 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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 #include #include #include #include #include "nxterm.h" #ifdef CONFIG_DEBUG_FEATURES /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: nxterm_semwait and nxterm_sempost * * Description: * If debug is on, then lower level code may attempt console output while * we are doing console output! In this case, we will toss the nested * output to avoid deadlocks and infinite loops. * * Input Parameters: * priv - Driver data structure * * Returned Value: * * ****************************************************************************/ int nxterm_semwait(FAR struct nxterm_state_s *priv) { pid_t me; int ret; /* Does I already hold the semaphore */ me = getpid(); if (priv->holder != me) { /* No.. then wait until the thread that does hold it is finished with it */ ret = nxsem_wait(&priv->exclsem); if (ret == OK) { /* No I hold the semaphore */ priv->holder = me; } return ret; } /* Abort, abort, abort! I have been re-entered */ return -EBUSY; } int nxterm_sempost(FAR struct nxterm_state_s *priv) { pid_t me = getpid(); /* Make sure that I really hold the semaphore */ DEBUGASSERT(priv->holder == me); /* Then let go of it */ priv->holder = NO_HOLDER; return nxsem_post(&priv->exclsem); } #endif /* CONFIG_DEBUG_FEATURES */