63 lines
1.2 KiB
C++
63 lines
1.2 KiB
C++
/*
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* \brief Lock implementation
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* \author Norman Feske
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* \date 2007-10-15
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*/
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/*
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* Copyright (C) 2007-2017 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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/* Genode includes */
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#include <base/cancelable_lock.h>
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#include <base/thread.h>
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#include <cpu/atomic.h>
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#include <cpu/memory_barrier.h>
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/* L4/Fiasco includes */
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namespace Fiasco {
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#include <l4/sys/ipc.h>
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}
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using namespace Genode;
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Cancelable_lock::Cancelable_lock(Cancelable_lock::State initial)
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: _state(UNLOCKED), _owner(nullptr)
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{
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if (initial == LOCKED)
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lock();
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}
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void Cancelable_lock::lock()
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{
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Applicant myself(Thread::myself());
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lock(myself);
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}
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void Cancelable_lock::lock(Applicant &myself)
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{
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/*
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* XXX: How to notice cancel-blocking signals issued when being outside the
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* 'l4_ipc_sleep' system call?
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*/
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while (!Genode::cmpxchg(&_state, UNLOCKED, LOCKED))
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if (Fiasco::l4_ipc_sleep(Fiasco::l4_ipc_timeout(0, 0, 500, 0)) != L4_IPC_RETIMEOUT)
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throw Genode::Blocking_canceled();
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_owner = myself;
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}
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void Cancelable_lock::unlock()
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{
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_owner = Applicant(nullptr);
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Genode::memory_barrier();
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_state = UNLOCKED;
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}
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