diff --git a/src/libipc/platform/posix/mutex.h b/src/libipc/platform/posix/mutex.h index 8a4ac5f..a19ace8 100644 --- a/src/libipc/platform/posix/mutex.h +++ b/src/libipc/platform/posix/mutex.h @@ -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); diff --git a/src/libipc/platform/posix/shm_posix.cpp b/src/libipc/platform/posix/shm_posix.cpp index 968a202..bcf7918 100644 --- a/src/libipc/platform/posix/shm_posix.cpp +++ b/src/libipc/platform/posix/shm_posix.cpp @@ -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