From 5759ea19fb52d678872999936e6a215e963b30d5 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Mon, 3 Apr 2023 13:19:11 +0200
Subject: [PATCH] Kernel: Mark sys$alarm as not needing the big lock

Access to Process::m_alarm_timer is serialized via SpinlockProtected,
so there's no longer need for this syscall to use the big lock.
---
 Kernel/API/Syscall.h      | 2 +-
 Kernel/Syscalls/alarm.cpp | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/Kernel/API/Syscall.h b/Kernel/API/Syscall.h
index 8e19dbd2be..4134eb0cc2 100644
--- a/Kernel/API/Syscall.h
+++ b/Kernel/API/Syscall.h
@@ -47,7 +47,7 @@ enum class NeedsBigProcessLock {
 #define ENUMERATE_SYSCALLS(S)                               \
     S(accept4, NeedsBigProcessLock::No)                     \
     S(adjtime, NeedsBigProcessLock::No)                     \
-    S(alarm, NeedsBigProcessLock::Yes)                      \
+    S(alarm, NeedsBigProcessLock::No)                       \
     S(allocate_tls, NeedsBigProcessLock::Yes)               \
     S(anon_create, NeedsBigProcessLock::No)                 \
     S(annotate_mapping, NeedsBigProcessLock::No)            \
diff --git a/Kernel/Syscalls/alarm.cpp b/Kernel/Syscalls/alarm.cpp
index c73458d482..66ddc5211a 100644
--- a/Kernel/Syscalls/alarm.cpp
+++ b/Kernel/Syscalls/alarm.cpp
@@ -12,10 +12,10 @@ namespace Kernel {
 
 ErrorOr<FlatPtr> Process::sys$alarm(unsigned seconds)
 {
-    VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this);
+    VERIFY_NO_PROCESS_BIG_LOCK(this);
     TRY(require_promise(Pledge::stdio));
-    unsigned previous_alarm_remaining = 0;
     return m_alarm_timer.with([&](auto& timer) -> ErrorOr<FlatPtr> {
+        unsigned previous_alarm_remaining = 0;
         if (timer) {
             bool was_in_use = false;
             if (TimerQueue::the().cancel_timer(*timer, &was_in_use)) {