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/* Copyright (C) 2004 David Decotigny
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
USA.
*/
#ifndef _SOS_KSYNCH_H_
#define _SOS_KSYNCH_H_
/**
* @file synch.h
*
* Common kernel synchronisation primitives.
*/
#include <sos/errno.h>
#include <sos/kwaitq.h>
/* ====================================================================
* Kernel semaphores, NON-recursive
*/
/**
* The structure of a (NON-RECURSIVE) kernel Semaphore
*/
struct sos_ksema
{
int value;
struct sos_kwaitq kwaitq;
};
/*
* Initialize a kernel semaphore structure with the given name
*
* @param name Name of the semaphore (for debugging purpose only; safe
* [deep copied])
*
* @param initial_value The value of the semaphore before any up/down
*/
sos_ret_t sos_ksema_init(struct sos_ksema *sema, const char *name,
int initial_value);
/*
* De-initialize a kernel semaphore
*
* @return -SOS_EBUSY when semaphore could not be de-initialized
* because at least a thread is in the waitq.
*/
sos_ret_t sos_ksema_dispose(struct sos_ksema *sema);
/*
* Enters the semaphore
*
* @param timeout Maximum time to wait for the semaphore. Or NULL for
* "no limit". Updated on return to reflect the time remaining (0 when
* timeout has been triggered)
*
* @return -SOS_EINTR when timeout was triggered or when another waitq
* woke us up.
*
* @note This is a BLOCKING FUNCTION
*/
sos_ret_t sos_ksema_down(struct sos_ksema *sema,
struct sos_time *timeout);
/*
* Try to enter the semaphore without blocking.
*
* @return -SOS_EBUSY when locking the semaphore would block
*/
sos_ret_t sos_ksema_trydown(struct sos_ksema *sema);
/**
* Increments the semaphore's value, eventually waking up a thread
*/
sos_ret_t sos_ksema_up(struct sos_ksema *sema);
/* ====================================================================
* Kernel mutex (ie binary semaphore with strong ownership),
* NON-recursive !
*/
/**
* The structure of a (NON-RECURSIVE) kernel Mutex
*/
struct sos_kmutex
{
struct sos_thread *owner;
struct sos_kwaitq kwaitq;
};
/*
* Initialize a kernel mutex structure with the given name
*
* @param name Name of the mutex (for debugging purpose only; safe
* [deep copied])
*
* @param initial_value The value of the mutex before any up/down
*/
sos_ret_t sos_kmutex_init(struct sos_kmutex *mutex, const char *name);
/*
* De-initialize a kernel mutex
*
* @return -SOS_EBUSY when mutex could not be de-initialized
* because at least a thread is in the waitq.
*/
sos_ret_t sos_kmutex_dispose(struct sos_kmutex *mutex);
/*
* Lock the mutex. If the same thread multiply locks the same mutex,
* it won't hurt (no deadlock, return value = -SOS_EBUSY).
*
* @param timeout Maximum time to wait for the mutex. Or NULL for "no
* limit". Updated on return to reflect the time remaining (0 when
* timeout has been triggered)
*
* @return -SOS_EINTR when timeout was triggered or when another waitq
* woke us up, -SOS_EBUSY when the thread already owns the mutex.
*
* @note This is a BLOCKING FUNCTION
*/
sos_ret_t sos_kmutex_lock(struct sos_kmutex *mutex,
struct sos_time *timeout);
/*
* Try to lock the mutex without blocking.
*
* @return -SOS_EBUSY when locking the mutex would block
*/
sos_ret_t sos_kmutex_trylock(struct sos_kmutex *mutex);
/**
* Unlock the mutex, eventually waking up a thread
*
* @return -SOS_EPERM when the calling thread is NOT the owner of the
* mutex
*/
sos_ret_t sos_kmutex_unlock(struct sos_kmutex *mutex);
#endif /* _SOS_KSYNCH_H_ */
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