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Skip munmap when exiting via a signal

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avoid munmap of memory when exiting via signal, which avoids side effects such
as triggering asserts or (caught) segfaults while the process exists.

closes https://github.com/official-stockfish/Stockfish/pull/6542

No functional change
This commit is contained in:
anematode
2026-01-15 22:17:14 +01:00
committed by Joost VandeVondele
parent 0b9068d510
commit 5b8b304ebd
1 changed files with 14 additions and 8 deletions
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src/shm_linux.h
+14 -8
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@@ -67,7 +67,7 @@ struct ShmHeader {
class SharedMemoryBase { class SharedMemoryBase {
public: public:
virtual ~SharedMemoryBase() = default; virtual ~SharedMemoryBase() = default;
virtual void close() noexcept = 0; virtual void close(bool skip_unmap = false) noexcept = 0;
virtual const std::string& name() const noexcept = 0; virtual const std::string& name() const noexcept = 0;
}; };
@@ -87,10 +87,10 @@ class SharedMemoryRegistry {
active_instances_.erase(instance); active_instances_.erase(instance);
} }
static void cleanup_all() noexcept { static void cleanup_all(bool skip_unmap = false) noexcept {
std::scoped_lock lock(registry_mutex_); std::scoped_lock lock(registry_mutex_);
for (auto* instance : active_instances_) for (auto* instance : active_instances_)
instance->close(); instance->close(skip_unmap);
active_instances_.clear(); active_instances_.clear();
} }
}; };
@@ -103,12 +103,14 @@ class CleanupHooks {
static std::once_flag register_once_; static std::once_flag register_once_;
static void handle_signal(int sig) noexcept { static void handle_signal(int sig) noexcept {
SharedMemoryRegistry::cleanup_all(); // Search threads may still be running, so skip munmap (but still perform
// other cleanup actions). The memory mappings will be released on exit.
SharedMemoryRegistry::cleanup_all(true);
_Exit(128 + sig); _Exit(128 + sig);
} }
static void register_signal_handlers() noexcept { static void register_signal_handlers() noexcept {
std::atexit([]() { SharedMemoryRegistry::cleanup_all(); }); std::atexit([]() { SharedMemoryRegistry::cleanup_all(true); });
constexpr int signals[] = {SIGHUP, SIGINT, SIGQUIT, SIGILL, SIGABRT, SIGFPE, constexpr int signals[] = {SIGHUP, SIGINT, SIGQUIT, SIGILL, SIGABRT, SIGFPE,
SIGSEGV, SIGTERM, SIGBUS, SIGSYS, SIGXCPU, SIGXFSZ}; SIGSEGV, SIGTERM, SIGBUS, SIGSYS, SIGXCPU, SIGXFSZ};
@@ -318,7 +320,7 @@ class SharedMemory: public detail::SharedMemoryBase {
} }
} }
void close() noexcept override { void close(bool skip_unmap = false) noexcept override {
if (fd_ == -1 && mapped_ptr_ == nullptr) if (fd_ == -1 && mapped_ptr_ == nullptr)
return; return;
@@ -345,7 +347,10 @@ class SharedMemory: public detail::SharedMemoryBase {
decrement_refcount_relaxed(); decrement_refcount_relaxed();
} }
unmap_region(); if (skip_unmap)
mapped_ptr_ = nullptr;
else
unmap_region();
if (remove_region) if (remove_region)
shm_unlink(name_.c_str()); shm_unlink(name_.c_str());
@@ -359,7 +364,8 @@ class SharedMemory: public detail::SharedMemoryBase {
fd_ = -1; fd_ = -1;
} }
reset(); if (!skip_unmap)
reset();
} }
const std::string& name() const noexcept override { return name_; } const std::string& name() const noexcept override { return name_; }