From bbc5f042d31646a1a94d63bb548fc9659acc0220 Mon Sep 17 00:00:00 2001
From: Mathias Kraus <elboberido@m-hias.de>
Date: Sat, 21 Sep 2024 19:04:31 +0200
Subject: [PATCH] iox-#2301 Ensure SpinLock is inter-process safe

---
 .../concurrent/sync/include/iox/spin_lock.hpp        |  2 ++
 iceoryx_hoofs/concurrent/sync/source/spin_lock.cpp   | 12 +++++++++---
 2 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/iceoryx_hoofs/concurrent/sync/include/iox/spin_lock.hpp b/iceoryx_hoofs/concurrent/sync/include/iox/spin_lock.hpp
index 4958cfeefd..32c66d4f67 100644
--- a/iceoryx_hoofs/concurrent/sync/include/iox/spin_lock.hpp
+++ b/iceoryx_hoofs/concurrent/sync/include/iox/spin_lock.hpp
@@ -17,6 +17,7 @@
 #ifndef IOX_HOOFS_CONCURRENT_SYNC_SPIN_LOCK_HPP
 #define IOX_HOOFS_CONCURRENT_SYNC_SPIN_LOCK_HPP
 
+#include "iceoryx_platform/unistd.hpp"
 #include "iox/atomic.hpp"
 #include "iox/lock_interface.hpp"
 
@@ -63,6 +64,7 @@ class SpinLock : public LockInterface<SpinLock>
     concurrent::AtomicFlag m_lock_flag =
         ATOMIC_FLAG_INIT; // NOTE: only initialization via assignment is guaranteed to work
     const concurrent::Atomic<bool> m_recursive{false};
+    concurrent::Atomic<pid_t> m_pid{0};
     concurrent::Atomic<uint64_t> m_recursive_count{0};
     concurrent::Atomic<std::thread::id> m_tid{};
 };
diff --git a/iceoryx_hoofs/concurrent/sync/source/spin_lock.cpp b/iceoryx_hoofs/concurrent/sync/source/spin_lock.cpp
index d42c4a217e..dfe8bb2172 100644
--- a/iceoryx_hoofs/concurrent/sync/source/spin_lock.cpp
+++ b/iceoryx_hoofs/concurrent/sync/source/spin_lock.cpp
@@ -41,9 +41,10 @@ SpinLock::SpinLock(const LockBehavior lock_behavior) noexcept
 
 expected<void, LockError> SpinLock::lock_impl() noexcept
 {
+    auto pid = getpid();
     auto tid = std::this_thread::get_id();
 
-    if (m_tid.load() == tid)
+    if (m_pid.load() == pid && m_tid.load() == tid)
     {
         if (m_recursive.load(std::memory_order_relaxed))
         {
@@ -58,6 +59,7 @@ expected<void, LockError> SpinLock::lock_impl() noexcept
     detail::adaptive_wait spinner;
     spinner.wait_loop([this] { return this->m_lock_flag.test_and_set(std::memory_order_acquire); });
 
+    m_pid.store(pid);
     m_tid.store(tid);
     m_recursive_count.store(1);
 
@@ -66,9 +68,10 @@ expected<void, LockError> SpinLock::lock_impl() noexcept
 
 expected<void, UnlockError> SpinLock::unlock_impl() noexcept
 {
+    auto pid = getpid();
     auto tid = std::this_thread::get_id();
 
-    if (m_tid.load() != tid)
+    if (m_pid.load() != pid || m_tid.load() != tid)
     {
         return err(UnlockError::NOT_OWNED_BY_THREAD);
     }
@@ -81,6 +84,7 @@ expected<void, UnlockError> SpinLock::unlock_impl() noexcept
     auto old_recursive_count = m_recursive_count.fetch_sub(1);
     if (old_recursive_count == 1)
     {
+        m_pid.store(0);
         m_tid.store(std::thread::id());
         m_lock_flag.clear(std::memory_order_release);
     }
@@ -90,9 +94,10 @@ expected<void, UnlockError> SpinLock::unlock_impl() noexcept
 
 expected<TryLock, TryLockError> SpinLock::try_lock_impl() noexcept
 {
+    auto pid = getpid();
     auto tid = std::this_thread::get_id();
 
-    if (m_tid.load() == tid)
+    if (m_pid.load() == pid && m_tid.load() == tid)
     {
         if (m_recursive.load(std::memory_order_relaxed))
         {
@@ -105,6 +110,7 @@ expected<TryLock, TryLockError> SpinLock::try_lock_impl() noexcept
 
     if (!m_lock_flag.test_and_set(std::memory_order_acquire))
     {
+        m_pid.store(pid);
         m_tid.store(tid);
         m_recursive_count.store(1);