From e32c6356625cfacebff0c61d182f759abf6f508a Mon Sep 17 00:00:00 2001
From: Jarred Sumner <jarred@jarredsumner.com>
Date: Wed, 29 Jan 2025 02:35:17 -0800
Subject: [PATCH] Revert "Handle attempting to suspend while inside of epoll"

This reverts commit 1e14beda760e9c040412cc116b60f8170a90f675.
---
 Source/WTF/wtf/Threading.h              | 17 -----
 Source/WTF/wtf/posix/ThreadingPOSIX.cpp | 92 ++++---------------------
 2 files changed, 12 insertions(+), 97 deletions(-)

diff --git a/Source/WTF/wtf/Threading.h b/Source/WTF/wtf/Threading.h
index 16da90cfc080c..92e75474b9a8b 100644
--- a/Source/WTF/wtf/Threading.h
+++ b/Source/WTF/wtf/Threading.h
@@ -281,23 +281,6 @@ class WTF_CAPABILITY("is current") Thread : public ThreadSafeRefCounted<Thread>,
         m_savedLastStackTop = lastStackTop;
     }
 
-#if USE(BUN_JSC_ADDITIONS) && OS(LINUX)
-    enum ThreadStateFlags : uint8_t {
-        IsBlockedInSyscall = 1 << 0,
-        HasPendingSuspension = 1 << 1
-    };
-    std::atomic<uint8_t> m_threadState { 0 };
-
-    void setIsEnteringSyscall();
-
-    bool isBlockedInSyscall() const
-    {
-        return m_threadState.load(std::memory_order_relaxed) & IsBlockedInSyscall;
-    }
-
-    void setIsExitingSyscall();
-#endif
-
 #if OS(DARWIN)
     mach_port_t machThread() { return m_platformThread; }
 #endif
diff --git a/Source/WTF/wtf/posix/ThreadingPOSIX.cpp b/Source/WTF/wtf/posix/ThreadingPOSIX.cpp
index b07c29717e2e9..544a4bde2384f 100644
--- a/Source/WTF/wtf/posix/ThreadingPOSIX.cpp
+++ b/Source/WTF/wtf/posix/ThreadingPOSIX.cpp
@@ -216,49 +216,6 @@ void Thread::initializePlatformThreading()
 #endif
 }
 
-#if USE(BUN_JSC_ADDITIONS) && OS(LINUX)
-void Thread::setIsEnteringSyscall()
-{
-    uint8_t oldState;
-    uint8_t newState;
-    do {
-        oldState = m_threadState.load(std::memory_order_relaxed);
-        newState = oldState | IsBlockedInSyscall;
-    } while (!m_threadState.compare_exchange_weak(oldState, newState, std::memory_order_release));
-}
-
-void Thread::setIsExitingSyscall()
-{
-    uint8_t oldState;
-    uint8_t newState;
-    bool needsSuspend = false;
-
-    // Clear IsBlockedInSyscall flag and capture suspension state atomically
-    do {
-        oldState = m_threadState.load(std::memory_order_relaxed);
-        newState = oldState & ~IsBlockedInSyscall;
-        needsSuspend = oldState & HasPendingSuspension;
-        if (needsSuspend)
-            newState &= ~HasPendingSuspension;
-    } while (!m_threadState.compare_exchange_weak(oldState, newState, std::memory_order_acquire));
-
-    if (needsSuspend) {
-        // Signal that we're suspended
-        globalSemaphoreForSuspendResume->post();
-
-        sigset_t blockedSignalSet;
-        sigfillset(&blockedSignalSet);
-        sigdelset(&blockedSignalSet, g_wtfConfig.sigThreadSuspendResume);
-        sigsuspend(&blockedSignalSet);
-
-        m_platformRegisters = nullptr;
-
-        // Signal that we're resumed
-        globalSemaphoreForSuspendResume->post();
-    }
-}
-#endif
-
 #if OS(LINUX)
 ThreadIdentifier Thread::currentID()
 {
@@ -498,33 +455,19 @@ auto Thread::suspend(const ThreadSuspendLocker&) -> Expected<void, PlatformSuspe
 #else
     if (!m_suspendCount) {
         targetThread.store(this);
-#if USE(BUN_JSC_ADDITIONS) && OS(LINUX)
-        // Try to mark suspension pending if in syscall
-        uint8_t oldState = m_threadState.load(std::memory_order_relaxed);
-        if (oldState & IsBlockedInSyscall) {
-            // Thread is in syscall, set pending suspension
-            uint8_t newState;
-            do {
-                newState = oldState | HasPendingSuspension;
-            } while (!m_threadState.compare_exchange_weak(oldState, newState, std::memory_order_release));
-        } else {
-#endif
-            while (true) {
-                // We must use pthread_kill to avoid queue-overflow problem with real-time signals.
-                int result = pthread_kill(m_handle, g_wtfConfig.sigThreadSuspendResume);
-                if (result)
-                    return makeUnexpected(result);
-                globalSemaphoreForSuspendResume->wait();
-                if (m_platformRegisters)
-                    break;
-                // Because of an alternative signal stack, we failed to suspend this thread.
-                // Retry suspension again after yielding.
-                Thread::yield();
-            }
-
-#if USE(BUN_JSC_ADDITIONS) && OS(LINUX)
+
+        while (true) {
+            // We must use pthread_kill to avoid queue-overflow problem with real-time signals.
+            int result = pthread_kill(m_handle, g_wtfConfig.sigThreadSuspendResume);
+            if (result)
+                return makeUnexpected(result);
+            globalSemaphoreForSuspendResume->wait();
+            if (m_platformRegisters)
+                break;
+            // Because of an alternative signal stack, we failed to suspend this thread.
+            // Retry suspension again after yielding.
+            Thread::yield();
         }
-#endif
     }
     ++m_suspendCount;
     return { };
@@ -546,17 +489,6 @@ void Thread::resume(const ThreadSuspendLocker&)
         // In this implementaiton, we take (3). m_suspendCount is used to distinguish it.
         // Note that we must use pthread_kill to avoid queue-overflow problem with real-time signals.
         targetThread.store(this);
-
-#if USE(BUN_JSC_ADDITIONS) && OS(LINUX)
-        // Clear any pending suspension flag
-        uint8_t oldState;
-        do {
-            oldState = m_threadState.load(std::memory_order_relaxed);
-        } while (!m_threadState.compare_exchange_weak(oldState,
-            oldState & ~HasPendingSuspension,
-            std::memory_order_release));
-#endif
-
         if (pthread_kill(m_handle, g_wtfConfig.sigThreadSuspendResume) == ESRCH)
             return;
         globalSemaphoreForSuspendResume->wait();