4342d0d234
Patch prevents following bugs: * In sleep_forever the thread return from semaphore down if cap is revoked during destruction of a thread. This causes an endless loop consuming time not available for other threads. * In lock_helper and cap_sel_alloc the thread return from the lock() method even if the semaphore down call failed because of an revoked semaphore. This lead to the situation that a thread subject to de-construction returns from the lock method, but not holding the lock, entering the critical section and modifying state inside the critical section. Another thread in parallel already in the critical section or entering the critical section also modifies the state. This lead to curious bugs ... * thread_nova, thread_start, irq_session Detect early bugs if the SM is gone unexpectedly where it should never happen.
95 lines
2.2 KiB
C++
95 lines
2.2 KiB
C++
/*
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* \brief NOVA-specific signal-source client interface
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* \author Norman Feske
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* \date 2010-02-03
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*
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* On NOVA, the signal source server does not provide a blocking
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* 'wait_for_signal' function because this kernel does no support
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* out-of-order IPC replies. Instead, we use a shared semaphore
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* to let the client block until a signal is present at the
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* server. The shared semaphore gets initialized with the first
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* call of 'wait_for_signal()'.
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*/
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/*
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* Copyright (C) 2010-2012 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 General Public License version 2.
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*/
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#ifndef _INCLUDE__SIGNAL_SESSION__SOURCE_CLIENT_H_
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#define _INCLUDE__SIGNAL_SESSION__SOURCE_CLIENT_H_
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#include <base/rpc_client.h>
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#include <signal_session/nova_source.h>
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/* NOVA includes */
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#include <nova/syscalls.h>
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#include <nova/util.h>
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namespace Genode {
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class Signal_source_client : public Rpc_client<Nova_signal_source>
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{
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private:
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/**
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* Capability referring to a NOVA semaphore
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*/
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Native_capability _sem;
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/**
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* Request NOVA semaphore from signal-source server
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*/
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void _init_sem()
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{
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/* initialize semaphore only once */
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if (_sem.valid()) return;
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/* request mapping of semaphore capability selector */
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_sem = call<Rpc_request_semaphore>();
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}
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public:
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/**
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* Constructor
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*/
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Signal_source_client(Signal_source_capability cap)
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: Rpc_client<Nova_signal_source>(
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static_cap_cast<Nova_signal_source>(cap)) { }
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/*****************************
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** Signal source interface **
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*****************************/
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Signal wait_for_signal()
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{
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/*
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* Make sure that we have acquired the
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* semaphore from the server
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*/
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_init_sem();
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/*
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* Block on semaphore, will be unblocked if
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* signal is available
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*/
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if (Nova::sm_ctrl(_sem.local_name(),
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Nova::SEMAPHORE_DOWN))
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nova_die();
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/*
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* Now that the server has unblocked the semaphore, we are sure
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* that there is a signal pending. The following 'wait_for_signal'
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* request will be immediately answered.
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*/
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return call<Rpc_wait_for_signal>();
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}
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};
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}
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#endif /* _INCLUDE__SIGNAL_SESSION__SOURCE_CLIENT_H_ */
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