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[Offload] Implement olShutDown #144055

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Merged
merged 4 commits into from
Jun 30, 2025
Merged

[Offload] Implement olShutDown #144055

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364ad9a
[Offload] Implement `olShutDown`
RossBrunton Jun 12, 2025
42ee278
Move init to olInit
RossBrunton Jun 27, 2025
782d74d
Reorder logic
RossBrunton Jun 30, 2025
a304dd7
Work around race condition
RossBrunton Jun 30, 2025
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21 changes: 12 additions & 9 deletions offload/liboffload/src/OffloadImpl.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -96,7 +96,9 @@ struct AllocInfo {

// Global shared state for liboffload
struct OffloadContext;
static OffloadContext *OffloadContextVal;
// This pointer is non-null if and only if the context is valid and fully
// initialized
static std::atomic<OffloadContext *> OffloadContextVal;
std::mutex OffloadContextValMutex;
struct OffloadContext {
OffloadContext(OffloadContext &) = delete;
Expand Down Expand Up @@ -147,9 +149,7 @@ constexpr ol_platform_backend_t pluginNameToBackend(StringRef Name) {
#define PLUGIN_TARGET(Name) extern "C" GenericPluginTy *createPlugin_##Name();
#include "Shared/Targets.def"

Error initPlugins() {
auto &Context = OffloadContext::get();

Error initPlugins(OffloadContext &Context) {
// Attempt to create an instance of each supported plugin.
#define PLUGIN_TARGET(Name) \
do { \
Expand Down Expand Up @@ -199,8 +199,11 @@ Error olInit_impl() {
return Plugin::success();
}

OffloadContextVal = new OffloadContext{};
Error InitResult = initPlugins();
// Use a temporary to ensure that entry points querying OffloadContextVal do
// not get a partially initialized context
auto *NewContext = new OffloadContext{};
Error InitResult = initPlugins(*NewContext);
OffloadContextVal.store(NewContext);
OffloadContext::get().RefCount++;
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@jhuber6 jhuber6 Jun 27, 2025

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Shouldn't we be calling new and delete on this if it's null?

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@RossBrunton RossBrunton Jun 27, 2025

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The context is new'd in initPlugins(), but perhaps it makes sense doing it in olInit_impl, so I'll move it here.


return InitResult;
Expand All @@ -213,18 +216,18 @@ Error olShutDown_impl() {
return Error::success();

llvm::Error Result = Error::success();
auto *OldContext = OffloadContextVal.exchange(nullptr);
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@jhuber6 jhuber6 Jun 30, 2025

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Yeah, forgot to mention that this needed to be atomic since we're using it outside the mutex as a guard.


for (auto &P : OffloadContext::get().Platforms) {
for (auto &P : OldContext->Platforms) {
// Host plugin is nullptr and has no deinit
if (!P.Plugin)
continue;

if (auto Res = P.Plugin->deinit())
Result = llvm::joinErrors(std::move(Result), std::move(Res));
}
delete OffloadContextVal;
OffloadContextVal = nullptr;

delete OldContext;
return Result;
}

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