genode/base-codezero/src/base/lock/lock_helper.h

113 lines
2.6 KiB
C++

/*
* \brief Helper functions for the Lock implementation
* \author Norman Feske
* \date 2010-04-20
*
* For documentation about the interface, please revisit the 'base-pistachio'
* implementation.
*/
/*
* Copyright (C) 2010-2012 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
/* Genode includes */
#include <base/native_types.h>
#include <base/thread.h>
/* Codezero includes */
#include <codezero/syscalls.h>
/**
* Resolve 'Thread_base::myself' when not linking the thread library
*
* This weak symbol is primarily used by test cases. Most other Genode programs
* use the thread library. If the thread library is not used, 'myself' can only
* be called by the main thread, for which 'myself' is defined as zero.
*/
Genode::Thread_base * __attribute__((weak)) Genode::Thread_base::myself() { return 0; }
Genode::Native_utcb *Genode::Thread_base::utcb()
{
/*
* If 'utcb' is called on the object returned by 'myself',
* the 'this' pointer may be NULL (if the calling thread is
* the main thread). Therefore we handle this special case
* here.
*/
if (this == 0) return 0;
return &_context->utcb;
}
static Codezero::l4_mutex main_running_lock = { -1 };
static inline void thread_yield()
{
Codezero::l4_thread_switch(-1);
}
static inline bool thread_id_valid(Genode::Native_thread_id tid)
{
return tid.tid != Codezero::NILTHREAD;
}
static bool thread_check_stopped_and_restart(Genode::Native_thread_id tid)
{
if (!thread_id_valid(tid))
return false;
Codezero::l4_mutex_unlock(tid.running_lock);
return true;
}
static inline Genode::Native_thread_id thread_get_my_native_id()
{
using namespace Genode;
Codezero::l4_mutex *running_lock = 0;
/* obtain pointer to running lock of calling thread */
if (Thread_base::myself())
running_lock = Thread_base::myself()->utcb()->running_lock();
else {
running_lock = &main_running_lock;
if (running_lock->lock == -1) {
Codezero::l4_mutex_init(running_lock);
Codezero::l4_mutex_lock(running_lock); /* block on first mutex lock */
}
}
return Genode::Native_thread_id(Codezero::thread_myself(), running_lock);
}
static inline Genode::Native_thread_id thread_invalid_id()
{
return Genode::Native_thread_id(Codezero::NILTHREAD, 0);
}
static inline void thread_switch_to(Genode::Native_thread_id tid)
{
if (thread_id_valid(tid))
Codezero::l4_thread_switch(tid.tid);
}
static inline void thread_stop_myself()
{
Genode::Native_thread_id myself = thread_get_my_native_id();
Codezero::l4_mutex_lock(myself.running_lock);
}