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base: don't throw exceptions in 'Signal_receiver::pending_signal()'

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Issue #3922
This commit is contained in:
Christian Prochaska 2020-10-16 18:56:43 +02:00 committed by Christian Helmuth
parent f754e2a7d7
commit 50e0f3b977
7 changed files with 61 additions and 58 deletions
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6
repos/base-hw/src/lib/base/signal_receiver.cc
View File

@ -158,7 +158,7 @@ Signal Signal_receiver::pending_signal()
Signal::Data result;
_contexts.for_each_locked([&] (Signal_context &context) {
if (!context._pending) return;
if (!context._pending) return false;
_contexts.head(context._next);
context._pending = false;
@ -166,7 +166,7 @@ Signal Signal_receiver::pending_signal()
context._curr_signal = Signal::Data(0, 0);
Trace::Signal_received trace_event(context, result.num);
throw Context_ring::Break_for_each();
return true;
});
if (result.context) {
Mutex::Guard context_guard(result.context->_mutex);
@ -178,7 +178,7 @@ Signal Signal_receiver::pending_signal()
/* look for pending signals */
if (Kernel::pending_signal(Capability_space::capid(_cap)) != 0) {
throw Signal_not_pending();
return Signal();
}
/* read signal data */

18
repos/base/include/base/signal.h
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@ -88,7 +88,12 @@ class Genode::Signal
*/
Data() : context(0), num(0) { }
} _data;
} _data { };
/**
* Constructor for invalid signal
*/
Signal() { };
/**
* Constructor
@ -117,6 +122,7 @@ class Genode::Signal
Signal_context *context() { return _data.context; }
unsigned num() const { return _data.num; }
bool valid() const { return _data.context != nullptr; }
};
@ -299,9 +305,7 @@ class Genode::Signal_receiver : Noncopyable
do {
Mutex::Guard mutex_guard(context->_mutex);
try {
functor(*context);
} catch (Break_for_each) { return; }
if (functor(*context)) return;
context = context->_next;
} while (context != _head);
}
@ -352,7 +356,6 @@ class Genode::Signal_receiver : Noncopyable
*/
class Context_already_in_use { };
class Context_not_associated { };
class Signal_not_pending { };
/**
* Constructor
@ -401,10 +404,9 @@ class Genode::Signal_receiver : Noncopyable
void unblock_signal_waiter(Rpc_entrypoint &rpc_ep);
/**
* Retrieve pending signal
* Retrieve pending signal
*
* \throw 'Signal_not_pending' no pending signal found
* \return received signal
* \return received signal (invalid if no pending signal found)
*/
Signal pending_signal();

2
repos/base/src/core/signal_receiver.cc
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@ -50,6 +50,6 @@ void Signal_receiver::block_for_signal()
}
Signal Signal_receiver::pending_signal() {
throw Signal_not_pending(); }
return Signal(); }
void Signal_receiver::local_submit(Signal::Data) { ASSERT_NEVER_CALLED; }

74
repos/base/src/lib/base/entrypoint.cc
View File

@ -55,15 +55,17 @@ void Entrypoint::Signal_proxy_component::signal()
* Note, we handle only one signal here to ensure fairness between RPCs and
* signals.
*/
try {
Signal sig = ep._sig_rec->pending_signal();
Signal sig = ep._sig_rec->pending_signal();
if (sig.valid()) {
ep._dispatch_signal(sig);
if (sig.context()->level() == Signal_context::Level::Io) {
/* trigger the progress handler */
io_progress = true;
}
} catch (Signal_receiver::Signal_not_pending) { }
}
if (io_progress)
ep._handle_io_progress();
@ -185,8 +187,9 @@ bool Entrypoint::_wait_and_dispatch_one_io_signal(bool const dont_block)
for (;;) {
try {
Signal sig =_sig_rec->pending_signal();
Signal sig = _sig_rec->pending_signal();
if (sig.valid()) {
/* defer application-level signals */
if (sig.context()->level() == Signal_context::Level::App) {
@ -196,40 +199,39 @@ bool Entrypoint::_wait_and_dispatch_one_io_signal(bool const dont_block)
_dispatch_signal(sig);
break;
}
} catch (Signal_receiver::Signal_not_pending) {
if (dont_block)
return false;
if (dont_block)
return false;
{
/*
* The signal-proxy thread as well as the entrypoint via
* 'wait_and_dispatch_one_io_signal' never call
* 'block_for_signal()' without the '_block_for_signal_mutex'
* aquired. The signal-proxy thread also flags when it was
* unblocked by an incoming signal and delivers the signal via
* RPC in '_signal_proxy_delivers_signal'.
*/
Mutex::Guard guard { _block_for_signal_mutex };
{
/*
* The signal-proxy thread as well as the entrypoint via
* 'wait_and_dispatch_one_io_signal' never call
* 'block_for_signal()' without the '_block_for_signal_mutex'
* aquired. The signal-proxy thread also flags when it was
* unblocked by an incoming signal and delivers the signal via
* RPC in '_signal_proxy_delivers_signal'.
*/
Mutex::Guard guard { _block_for_signal_mutex };
/*
* If the signal proxy is blocked in the signal-delivery
* RPC but the call did not yet arrive in the entrypoint
* (_signal_proxy_delivers_signal == true), we acknowledge the
* delivery here (like in 'Signal_proxy_component::signal()') and
* retry to fetch one pending signal at the beginning of the
* loop above. Otherwise, we block for the next incoming
* signal.
*
* There exist cases were we already processed the signal
* flagged in '_signal_proxy_delivers_signal' and will end
* up here again. In these cases we also 'block_for_signal()'.
*/
if (_signal_proxy_delivers_signal)
_signal_proxy_delivers_signal = false;
else
_sig_rec->block_for_signal();
}
/*
* If the signal proxy is blocked in the signal-delivery
* RPC but the call did not yet arrive in the entrypoint
* (_signal_proxy_delivers_signal == true), we acknowledge the
* delivery here (like in 'Signal_proxy_component::signal()') and
* retry to fetch one pending signal at the beginning of the
* loop above. Otherwise, we block for the next incoming
* signal.
*
* There exist cases were we already processed the signal
* flagged in '_signal_proxy_delivers_signal' and will end
* up here again. In these cases we also 'block_for_signal()'.
*/
if (_signal_proxy_delivers_signal)
_signal_proxy_delivers_signal = false;
else
_sig_rec->block_for_signal();
}
}

10
repos/base/src/lib/base/signal.cc
View File

@ -235,13 +235,14 @@ void Signal_receiver::block_for_signal()
_signal_available.down();
}
Signal Signal_receiver::pending_signal()
{
Mutex::Guard contexts_guard(_contexts_mutex);
Signal::Data result;
_contexts.for_each_locked([&] (Signal_context &context) {
_contexts.for_each_locked([&] (Signal_context &context) -> bool {
if (!context._pending) return;
if (!context._pending) return false;
_contexts.head(context._next);
context._pending = false;
@ -249,7 +250,7 @@ Signal Signal_receiver::pending_signal()
context._curr_signal = Signal::Data(0, 0);
Trace::Signal_received trace_event(context, result.num);
throw Context_ring::Break_for_each();
return true;
});
if (result.context) {
Mutex::Guard context_guard(result.context->_mutex);
@ -268,10 +269,9 @@ Signal Signal_receiver::pending_signal()
* signal, we may have increased the semaphore already. In this case
* the signal-causing context is absent from the list.
*/
throw Signal_not_pending();
return Signal();
}
void Signal_receiver::unblock_signal_waiter(Rpc_entrypoint &)
{
_signal_available.up();

7
repos/base/src/lib/base/signal_common.cc
View File

@ -149,9 +149,10 @@ Signal Signal_receiver::wait_for_signal()
{
for (;;) {
try {
return pending_signal();
} catch (Signal_not_pending) { }
Signal sig = pending_signal();
if (sig.valid())
return sig;
/* block until the receiver has received a signal */
block_for_signal();

2
repos/ports/src/virtualbox5/thread.cc
View File

@ -160,8 +160,6 @@ extern "C" int pthread_create(pthread_t *thread, const pthread_attr_t *attr,
log("Upgrading memory for creation of "
"thread '", Cstring(rtthread->szName), "'");
cpu_connection(rtthread->enmType)->upgrade_ram(4096);
} catch (Genode::Signal_receiver::Signal_not_pending) {
error("signal not pending ?");
} catch (Out_of_caps) {
error("out of caps ...");
}