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Merge pull request #161 from mutouyun/fix/freebsd-mutex-unlock-timing

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Fix mutex unlock timing for FreeBSD multi-run stability
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木头云 2025-12-06 15:22:27 +08:00 committed by GitHub
commit addfe4f5cf
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2 changed files with 26 additions and 17 deletions
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26
src/libipc/platform/posix/mutex.h
View File

@ -150,21 +150,19 @@ public:
void close() noexcept {
if ((ref_ != nullptr) && (shm_ != nullptr) && (mutex_ != nullptr)) {
// Try to unlock the mutex before destroying it.
// This is important for robust mutexes on FreeBSD, which maintain
// a per-thread robust list. If we destroy a mutex while it's in
// the robust list (even if not locked), FreeBSD may encounter
// dangling pointers later, leading to segfaults.
// We ignore any errors from unlock() since:
// 1. If we don't hold the lock, EPERM is expected and harmless
// 2. If the mutex is already unlocked, this is a no-op
// 3. If there's an error, we still want to proceed with cleanup
::pthread_mutex_unlock(mutex_);
if (shm_->name() != nullptr) {
release_mutex(shm_->name(), [this] {
auto self_ref = ref_->fetch_sub(1, std::memory_order_relaxed);
if ((shm_->ref() <= 1) && (self_ref <= 1)) {
// Before destroying the mutex, try to unlock it.
// This is important for robust mutexes on FreeBSD, which maintain
// a per-thread robust list. If we destroy a mutex while it's locked
// or still in the robust list, FreeBSD may encounter dangling pointers
// later, leading to segfaults.
// Only unlock here (when we're the last reference) to avoid
// interfering with other threads that might be using the mutex.
::pthread_mutex_unlock(mutex_);
int eno;
if ((eno = ::pthread_mutex_destroy(mutex_)) != 0) {
ipc::error("fail pthread_mutex_destroy[%d]\n", eno);
@ -182,11 +180,11 @@ public:
void clear() noexcept {
if ((shm_ != nullptr) && (mutex_ != nullptr)) {
// Try to unlock before destroying, same reasoning as in close()
::pthread_mutex_unlock(mutex_);
if (shm_->name() != nullptr) {
release_mutex(shm_->name(), [this] {
// Unlock before destroying, same reasoning as in close()
::pthread_mutex_unlock(mutex_);
int eno;
if ((eno = ::pthread_mutex_destroy(mutex_)) != 0) {
ipc::error("fail pthread_mutex_destroy[%d]\n", eno);

17
src/libipc/platform/posix/shm_posix.cpp
View File

@ -173,7 +173,10 @@ std::int32_t release(id_t id) noexcept {
else if ((ret = acc_of(ii->mem_, ii->size_).fetch_sub(1, std::memory_order_acq_rel)) <= 1) {
::munmap(ii->mem_, ii->size_);
if (!ii->name_.empty()) {
::shm_unlink(ii->name_.c_str());
int unlink_ret = ::shm_unlink(ii->name_.c_str());
if (unlink_ret == -1) {
ipc::error("fail shm_unlink[%d]: %s\n", errno, ii->name_.c_str());
}
}
}
else ::munmap(ii->mem_, ii->size_);
@ -190,7 +193,10 @@ void remove(id_t id) noexcept {
auto name = std::move(ii->name_);
release(id);
if (!name.empty()) {
::shm_unlink(name.c_str());
int unlink_ret = ::shm_unlink(name.c_str());
if (unlink_ret == -1) {
ipc::error("fail shm_unlink[%d]: %s\n", errno, name.c_str());
}
}
}
@ -199,7 +205,12 @@ void remove(char const * name) noexcept {
ipc::error("fail remove: name is empty\n");
return;
}
::shm_unlink(name);
// For portable use, a shared memory object should be identified by name of the form /somename.
ipc::string op_name = ipc::string{"/"} + name;
int unlink_ret = ::shm_unlink(op_name.c_str());
if (unlink_ret == -1) {
ipc::error("fail shm_unlink[%d]: %s\n", errno, op_name.c_str());
}
}
} // namespace shm