From 46ad5f2a171080b3c1ee28c28b17bcfe8743b0a0 Mon Sep 17 00:00:00 2001
From: Jelle Raaijmakers <jelle@gmta.nl>
Date: Wed, 24 Nov 2021 18:49:43 +0100
Subject: [PATCH] Kernel: Fix `futex` syscall return values

We were returning `int`s from two functions that caused `ErrorOr` to
not recognize the error codes as a special case. For example,
`ETIMEDOUT` was returned as the positive number 66 resulting in all
kinds of defective behavior.

As a result, SDL2's timer subsystem was not working at all, since the
`SDL_MUTEX_TIMEDOUT` value was never returned.
---
 Kernel/Syscalls/futex.cpp | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/Kernel/Syscalls/futex.cpp b/Kernel/Syscalls/futex.cpp
index b03963a882..0769d4953b 100644
--- a/Kernel/Syscalls/futex.cpp
+++ b/Kernel/Syscalls/futex.cpp
@@ -99,7 +99,7 @@ ErrorOr<FlatPtr> Process::sys$futex(Userspace<const Syscall::SC_futex_params*> u
     auto user_address = FlatPtr(params.userspace_address);
     auto user_address2 = FlatPtr(params.userspace_address2);
 
-    auto do_wait = [&](u32 bitset) -> int {
+    auto do_wait = [&](u32 bitset) -> ErrorOr<FlatPtr> {
         bool did_create;
         RefPtr<FutexQueue> futex_queue;
         do {
@@ -136,7 +136,7 @@ ErrorOr<FlatPtr> Process::sys$futex(Userspace<const Syscall::SC_futex_params*> u
         return 0;
     };
 
-    auto do_requeue = [&](Optional<u32> val3) -> int {
+    auto do_requeue = [&](Optional<u32> val3) -> ErrorOr<FlatPtr> {
         auto user_value = user_atomic_load_relaxed(params.userspace_address);
         if (!user_value.has_value())
             return EFAULT;
@@ -204,7 +204,7 @@ ErrorOr<FlatPtr> Process::sys$futex(Userspace<const Syscall::SC_futex_params*> u
         if (!oldval.has_value())
             return EFAULT;
         atomic_thread_fence(AK::MemoryOrder::memory_order_acquire);
-        int result = do_wake(user_address, params.val, {});
+        auto result = do_wake(user_address, params.val, {});
         if (params.val2 > 0) {
             bool compare_result;
             switch (_FUTEX_CMP(params.val3)) {