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hw: introduce non-blocking signal checking

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* Introduces pending_signal syscall to check for new signals for the
  calling thread without blocking
* Implements pending_signal in the base-library specific for hw to use the
  new syscall

Fix #3217
This commit is contained in:
Stefan Kalkowski
2019-03-11 11:42:36 +01:00
committed by Christian Helmuth
parent 3e70b53165
commit 330692350e
7 changed files with 148 additions and 47 deletions
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3
repos/base/src/core/signal_receiver.cc
View File

@ -49,4 +49,7 @@ void Signal_receiver::block_for_signal()
sleep_forever();
}
Signal Signal_receiver::pending_signal() {
throw Signal_not_pending(); }
void Signal_receiver::local_submit(Signal::Data) { ASSERT_NEVER_CALLED; }

36
repos/base/src/lib/base/signal.cc
View File

@ -235,6 +235,42 @@ void Signal_receiver::block_for_signal()
_signal_available.down();
}
Signal Signal_receiver::pending_signal()
{
Lock::Guard contexts_lock_guard(_contexts_lock);
Signal::Data result;
_contexts.for_each_locked([&] (Signal_context &context) {
if (!context._pending) return;
_contexts.head(context._next);
context._pending = false;
result = context._curr_signal;
context._curr_signal = Signal::Data(0, 0);
Trace::Signal_received trace_event(context, result.num);
throw Context_ring::Break_for_each();
});
if (result.context) {
Lock::Guard lock_guard(result.context->_lock);
if (result.num == 0)
warning("returning signal with num == 0");
return result;
}
/*
* Normally, we should never arrive at this point because that would
* mean, the '_signal_available' semaphore was increased without
* registering the signal in any context associated to the receiver.
*
* However, if a context gets dissolved right after submitting a
* signal, we may have increased the semaphore already. In this case
* the signal-causing context is absent from the list.
*/
throw Signal_not_pending();
}
void Signal_receiver::unblock_signal_waiter(Rpc_entrypoint &)
{

37
repos/base/src/lib/base/signal_common.cc
View File

@ -159,43 +159,6 @@ Signal Signal_receiver::wait_for_signal()
}
Signal Signal_receiver::pending_signal()
{
Lock::Guard contexts_lock_guard(_contexts_lock);
Signal::Data result;
_contexts.for_each_locked([&] (Signal_context &context) {
if (!context._pending) return;
_contexts.head(context._next);
context._pending = false;
result = context._curr_signal;
context._curr_signal = Signal::Data(0, 0);
Trace::Signal_received trace_event(context, result.num);
throw Context_ring::Break_for_each();
});
if (result.context) {
Lock::Guard lock_guard(result.context->_lock);
if (result.num == 0)
warning("returning signal with num == 0");
return result;
}
/*
* Normally, we should never arrive at this point because that would
* mean, the '_signal_available' semaphore was increased without
* registering the signal in any context associated to the receiver.
*
* However, if a context gets dissolved right after submitting a
* signal, we may have increased the semaphore already. In this case
* the signal-causing context is absent from the list.
*/
throw Signal_not_pending();
}
Signal_receiver::~Signal_receiver()
{
Lock::Guard contexts_lock_guard(_contexts_lock);