bulbazord created this revision.
bulbazord added reviewers: jingham, teemperor, JDevlieghere, clayborg, aprantl.
bulbazord requested review of this revision.
Herald added a project: LLDB.
It is easy to accidentally introduce a deadlock by having the callback
passed to Language::ForEach also attempt to acquire the same lock. It
is easy enough to disallow the callback from calling anything in
Language directly, but it may happen through a series of other
function/method calls.
The solution I am proposing is to tighten the lock in Language::ForEach
so that it is only held as we gather the currently loaded language
plugins. We store them in a vector and then iterate through them with
the callback so that the callback can't introduce a callback.
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D109013
Files:
lldb/source/Target/Language.cpp
Index: lldb/source/Target/Language.cpp
===================================================================
--- lldb/source/Target/Language.cpp
+++ lldb/source/Target/Language.cpp
@@ -108,10 +108,18 @@
}
});
- std::lock_guard<std::mutex> guard(GetLanguagesMutex());
- LanguagesMap &map(GetLanguagesMap());
- for (const auto &entry : map) {
- if (!callback(entry.second.get()))
+ std::vector<Language *> loaded_plugins;
+ {
+ std::lock_guard<std::mutex> guard(GetLanguagesMutex());
+ LanguagesMap &map(GetLanguagesMap());
+ for (const auto &entry : map) {
+ if (entry.second)
+ loaded_plugins.push_back(entry.second.get());
+ }
+ }
+
+ for (auto *lang : loaded_plugins) {
+ if (!callback(lang))
break;
}
}
Index: lldb/source/Target/Language.cpp
===================================================================
--- lldb/source/Target/Language.cpp
+++ lldb/source/Target/Language.cpp
@@ -108,10 +108,18 @@
}
});
- std::lock_guard<std::mutex> guard(GetLanguagesMutex());
- LanguagesMap &map(GetLanguagesMap());
- for (const auto &entry : map) {
- if (!callback(entry.second.get()))
+ std::vector<Language *> loaded_plugins;
+ {
+ std::lock_guard<std::mutex> guard(GetLanguagesMutex());
+ LanguagesMap &map(GetLanguagesMap());
+ for (const auto &entry : map) {
+ if (entry.second)
+ loaded_plugins.push_back(entry.second.get());
+ }
+ }
+
+ for (auto *lang : loaded_plugins) {
+ if (!callback(lang))
break;
}
}
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