Kernel/PCI: Don't hold spinlocks when doing fast device enumeration

Instead, hold the lock while we copy the contents to a stack-based
Vector then iterate on it without any locking.

Because we rely on heap allocations, we need to propagate errors back
in case of OOM condition, therefore, both PCI::enumerate API function
and PCI::Access::add_host_controller_and_enumerate_attached_devices use
now a ErrorOr<void> return value to propagate errors. OOM Error can only
occur when enumerating the m_device_identifiers vector under a spinlock
and trying to expand the temporary Vector which will be used locklessly
to actually iterate over the PCI::DeviceIdentifiers objects.

1 files changed, 2 insertions, 2 deletions

diff --git a/Kernel/Devices/Audio/Management.cpp b/Kernel/Devices/Audio/Management.cpp
index e444d3351f..abf57a4991 100644
--- a/Kernel/Devices/Audio/Management.cpp
+++ b/Kernel/Devices/Audio/Management.cpp
@@ -39,7 +39,7 @@ UNMAP_AFTER_INIT AudioManagement::AudioManagement()
 UNMAP_AFTER_INIT void AudioManagement::enumerate_hardware_controllers()
 {
     if (!PCI::Access::is_disabled()) {
-        PCI::enumerate([&](PCI::DeviceIdentifier const& device_identifier) {
+        MUST(PCI::enumerate([&](PCI::DeviceIdentifier const& device_identifier) {
             // Note: Only consider PCI audio controllers
             if (device_identifier.class_code().value() != to_underlying(PCI::ClassID::Multimedia)
                 || device_identifier.subclass_code().value() != to_underlying(PCI::Multimedia::SubclassID::AudioController))
@@ -53,7 +53,7 @@ UNMAP_AFTER_INIT void AudioManagement::enumerate_hardware_controllers()
                 return;
             }
             m_controllers_list.append(ac97_device.release_value());
-        });
+        }));
     }
 }