Kernel: Use shared locking mode in some places

The notable piece of code that remains to be converted is Ext2FS.

Kernel/FileSystem/FileDescription.cpp

@@ -168,7 +168,7 @@ ByteBuffer FileDescription::read_entire_file()
 
 ssize_t FileDescription::get_dir_entries(u8* buffer, ssize_t size)
 {
-    LOCKER(m_lock);
+    LOCKER(m_lock, Lock::Mode::Shared);
     if (!is_directory())
         return -ENOTDIR;
 

Kernel/FileSystem/ProcFS.cpp

@@ -491,7 +491,7 @@ Optional<KBuffer> procfs$net_arp(InodeIdentifier)
 {
     KBufferBuilder builder;
     JsonArraySerializer array { builder };
-    LOCKER(arp_table().lock());
+    LOCKER(arp_table().lock(), Lock::Mode::Shared);
     for (auto& it : arp_table().resource()) {
         auto obj = array.add_object();
         obj.add("mac_address", it.value.to_string());
@@ -983,7 +983,7 @@ static ByteBuffer read_sys_bool(InodeIdentifier inode_id)
     auto buffer = ByteBuffer::create_uninitialized(2);
     auto* lockable_bool = reinterpret_cast<Lockable<bool>*>(variable.address);
     {
-        LOCKER(lockable_bool->lock());
+        LOCKER(lockable_bool->lock(), Lock::Mode::Shared);
         buffer[0] = lockable_bool->resource() ? '1' : '0';
     }
     buffer[1] = '\n';
@@ -1013,7 +1013,7 @@ static ByteBuffer read_sys_string(InodeIdentifier inode_id)
     ASSERT(variable.type == SysVariable::Type::String);
 
     auto* lockable_string = reinterpret_cast<Lockable<String>*>(variable.address);
-    LOCKER(lockable_string->lock());
+    LOCKER(lockable_string->lock(), Lock::Mode::Shared);
     return lockable_string->resource().to_byte_buffer();
 }
 

Kernel/FileSystem/TmpFS.cpp

@@ -81,7 +81,7 @@ unsigned TmpFS::next_inode_index()
 
 RefPtr<Inode> TmpFS::get_inode(InodeIdentifier identifier) const
 {
-    LOCKER(m_lock);
+    LOCKER(m_lock, Lock::Mode::Shared);
     ASSERT(identifier.fsid() == fsid());
 
     auto it = m_inodes.find(identifier.index());
@@ -161,14 +161,14 @@ NonnullRefPtr<TmpFSInode> TmpFSInode::create_root(TmpFS& fs)
 
 InodeMetadata TmpFSInode::metadata() const
 {
-    LOCKER(m_lock);
+    LOCKER(m_lock, Lock::Mode::Shared);
 
     return m_metadata;
 }
 
 bool TmpFSInode::traverse_as_directory(Function<bool(const FS::DirectoryEntry&)> callback) const
 {
-    LOCKER(m_lock);
+    LOCKER(m_lock, Lock::Mode::Shared);
 
     if (!is_directory())
         return false;
@@ -183,7 +183,7 @@ bool TmpFSInode::traverse_as_directory(Function<bool(const FS::DirectoryEntry&)>
 
 ssize_t TmpFSInode::read_bytes(off_t offset, ssize_t size, u8* buffer, FileDescription*) const
 {
-    LOCKER(m_lock);
+    LOCKER(m_lock, Lock::Mode::Shared);
     ASSERT(!is_directory());
     ASSERT(size >= 0);
     ASSERT(offset >= 0);
@@ -247,7 +247,7 @@ ssize_t TmpFSInode::write_bytes(off_t offset, ssize_t size, const u8* buffer, Fi
 
 RefPtr<Inode> TmpFSInode::lookup(StringView name)
 {
-    LOCKER(m_lock);
+    LOCKER(m_lock, Lock::Mode::Shared);
     ASSERT(is_directory());
 
     if (name == ".")
@@ -263,7 +263,7 @@ RefPtr<Inode> TmpFSInode::lookup(StringView name)
 
 size_t TmpFSInode::directory_entry_count() const
 {
-    LOCKER(m_lock);
+    LOCKER(m_lock, Lock::Mode::Shared);
     ASSERT(is_directory());
     return 2 + m_children.size();
 }

Kernel/Net/LocalSocket.cpp

@@ -45,9 +45,9 @@ Lockable<InlineLinkedList<LocalSocket>>& LocalSocket::all_sockets()
     return *s_list;
 }
 
-void LocalSocket::for_each(Function<void(LocalSocket&)> callback)
+void LocalSocket::for_each(Function<void(const LocalSocket&)> callback)
 {
-    LOCKER(all_sockets().lock());
+    LOCKER(all_sockets().lock(), Lock::Mode::Shared);
     for (auto& socket : all_sockets().resource())
         callback(socket);
 }

Kernel/Net/LocalSocket.h

@@ -42,7 +42,7 @@ public:
     static KResultOr<NonnullRefPtr<Socket>> create(int type);
     virtual ~LocalSocket() override;
 
-    static void for_each(Function<void(LocalSocket&)>);
+    static void for_each(Function<void(const LocalSocket&)>);
 
     StringView socket_path() const;
     String absolute_path(const FileDescription& description) const override;

Kernel/Net/TCPSocket.cpp

@@ -38,9 +38,9 @@
 
 namespace Kernel {
 
-void TCPSocket::for_each(Function<void(TCPSocket&)> callback)
+void TCPSocket::for_each(Function<void(const TCPSocket&)> callback)
 {
-    LOCKER(sockets_by_tuple().lock());
+    LOCKER(sockets_by_tuple().lock(), Lock::Mode::Shared);
     for (auto& it : sockets_by_tuple().resource())
         callback(*it.value);
 }
@@ -80,7 +80,7 @@ Lockable<HashMap<IPv4SocketTuple, TCPSocket*>>& TCPSocket::sockets_by_tuple()
 
 RefPtr<TCPSocket> TCPSocket::from_tuple(const IPv4SocketTuple& tuple)
 {
-    LOCKER(sockets_by_tuple().lock());
+    LOCKER(sockets_by_tuple().lock(), Lock::Mode::Shared);
 
     auto exact_match = sockets_by_tuple().resource().get(tuple);
     if (exact_match.has_value())
@@ -230,7 +230,7 @@ void TCPSocket::send_outgoing_packets()
 
     auto now = kgettimeofday();
 
-    LOCKER(m_not_acked_lock);
+    LOCKER(m_not_acked_lock, Lock::Mode::Shared);
     for (auto& packet : m_not_acked) {
         timeval diff;
         timeval_sub(packet.tx_time, now, diff);

Kernel/Net/TCPSocket.h

@@ -37,7 +37,7 @@ namespace Kernel {
 class TCPSocket final : public IPv4Socket
     , public Weakable<TCPSocket> {
 public:
-    static void for_each(Function<void(TCPSocket&)>);
+    static void for_each(Function<void(const TCPSocket&)>);
     static NonnullRefPtr<TCPSocket> create(int protocol);
     virtual ~TCPSocket() override;
 

Kernel/Net/UDPSocket.cpp

@@ -34,9 +34,9 @@
 
 namespace Kernel {
 
-void UDPSocket::for_each(Function<void(UDPSocket&)> callback)
+void UDPSocket::for_each(Function<void(const UDPSocket&)> callback)
 {
-    LOCKER(sockets_by_port().lock());
+    LOCKER(sockets_by_port().lock(), Lock::Mode::Shared);
     for (auto it : sockets_by_port().resource())
         callback(*it.value);
 }
@@ -53,7 +53,7 @@ SocketHandle<UDPSocket> UDPSocket::from_port(u16 port)
 {
     RefPtr<UDPSocket> socket;
     {
-        LOCKER(sockets_by_port().lock());
+        LOCKER(sockets_by_port().lock(), Lock::Mode::Shared);
         auto it = sockets_by_port().resource().find(port);
         if (it == sockets_by_port().resource().end())
             return {};

Kernel/Net/UDPSocket.h

@@ -36,7 +36,7 @@ public:
     virtual ~UDPSocket() override;
 
     static SocketHandle<UDPSocket> from_port(u16);
-    static void for_each(Function<void(UDPSocket&)>);
+    static void for_each(Function<void(const UDPSocket&)>);
 
 private:
     explicit UDPSocket(int protocol);

Kernel/Process.cpp

@@ -704,7 +704,7 @@ int Process::sys$gethostname(char* buffer, ssize_t size)
         return -EINVAL;
     if (!validate_write(buffer, size))
         return -EFAULT;
-    LOCKER(*s_hostname_lock);
+    LOCKER(*s_hostname_lock, Lock::Mode::Shared);
     if ((size_t)size < (s_hostname->length() + 1))
         return -ENAMETOOLONG;
     copy_to_user(buffer, s_hostname->characters(), s_hostname->length() + 1);
@@ -2157,7 +2157,7 @@ int Process::sys$uname(utsname* buf)
     REQUIRE_PROMISE(stdio);
     if (!validate_write_typed(buf))
         return -EFAULT;
-    LOCKER(*s_hostname_lock);
+    LOCKER(*s_hostname_lock, Lock::Mode::Shared);
     if (s_hostname->length() + 1 > sizeof(utsname::nodename))
         return -ENAMETOOLONG;
     copy_to_user(buf->sysname, "SerenityOS", 11);

Kernel/SharedBuffer.cpp

@@ -39,7 +39,7 @@ Lockable<HashMap<int, NonnullOwnPtr<SharedBuffer>>>& shared_buffers()
 
 void SharedBuffer::sanity_check(const char* what)
 {
-    LOCKER(shared_buffers().lock());
+    LOCKER(shared_buffers().lock(), Lock::Mode::Shared);
 
     unsigned found_refs = 0;
     for (const auto& ref : m_refs)
@@ -56,7 +56,7 @@ void SharedBuffer::sanity_check(const char* what)
 
 bool SharedBuffer::is_shared_with(pid_t peer_pid)
 {
-    LOCKER(shared_buffers().lock());
+    LOCKER(shared_buffers().lock(), Lock::Mode::Shared);
     if (m_global)
         return true;
     for (auto& ref : m_refs) {