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VST3: prevent deadlock when restartComponent is called from Process

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This fixes an issue with Blendeq (and likely other plugins)
that call `restartComponent(Vst::kLatencyChanged) from the
in realtime context from plugin's process
This commit is contained in:
Robin Gareus 2023-02-13 17:32:02 +01:00
parent 8a23015ffb
commit 423a921301
Signed by: rgareus
GPG Key ID: A090BCE02CF57F04
1 changed files with 27 additions and 6 deletions
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33
libs/ardour/vst3_plugin.cc
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@ -1470,7 +1470,12 @@ VST3PI::restartComponent (int32 flags)
DEBUG_TRACE (DEBUG::VST3Callbacks, string_compose ("VST3PI::restartComponent %1%2\n", std::hex, flags));
if (flags & Vst::kReloadComponent) {
Glib::Threads::Mutex::Lock pl (_process_lock);
Glib::Threads::Mutex::Lock pl (_process_lock, Glib::Threads::NOT_LOCK);
if (!AudioEngine::instance()->in_process_thread()) {
pl.acquire ();
} else {
assert (0); // a plugin should not call this while processing
}
/* according to the spec, "The host has to unload completely
* the plug-in (controller/processor) and reload it."
*
@ -1483,14 +1488,30 @@ VST3PI::restartComponent (int32 flags)
activate ();
}
if (flags & Vst::kParamValuesChanged) {
Glib::Threads::Mutex::Lock pl (_process_lock);
Glib::Threads::Mutex::Lock pl (_process_lock, Glib::Threads::NOT_LOCK);
if (!AudioEngine::instance()->in_process_thread()) {
pl.acquire ();
}
update_shadow_data ();
}
if (flags & Vst::kLatencyChanged) {
Glib::Threads::Mutex::Lock pl (_process_lock);
/* need to re-activate the plugin as per spec */
deactivate ();
activate ();
/* https://forums.steinberg.net/t/reporting-latency-change/201601
* mentions that the host plugin should be deactivated before querying
* latency. However the official spec does not require this.
*
* However other implementations do not call setActive(false/true) when
* the latency changes, and Ardour does not require it either, latency
* changes are automatically picked up.
*/
Glib::Threads::Mutex::Lock pl (_process_lock, Glib::Threads::NOT_LOCK);
if (!AudioEngine::instance()->in_process_thread()) {
/* Some plugins (e.g BlendEQ) call this from the process,
* IPlugProcessor::ProcessBuffers. In that case taking the
* _process_lock would deadlock.
*/
pl.acquire ();
}
_plugin_latency.reset ();
}
if (flags & Vst::kIoChanged) {
warning << "VST3: Vst::kIoChanged (not implemented)" << endmsg;