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/Bus/PCI/API.cpp b/Kernel/Bus/PCI/API.cpp
index 9b26d4c049..f2c45bcb6d 100644
--- a/Kernel/Bus/PCI/API.cpp
+++ b/Kernel/Bus/PCI/API.cpp
@@ -17,9 +17,9 @@ u8 read8(Address address, PCI::RegisterOffset field) { return Access::the().read
 u16 read16(Address address, PCI::RegisterOffset field) { return Access::the().read16_field(address, to_underlying(field)); }
 u32 read32(Address address, PCI::RegisterOffset field) { return Access::the().read32_field(address, to_underlying(field)); }
 
-void enumerate(Function<void(DeviceIdentifier const&)> callback)
+ErrorOr<void> enumerate(Function<void(DeviceIdentifier const&)> callback)
 {
-    Access::the().fast_enumerate(callback);
+    return Access::the().fast_enumerate(callback);
 }
 
 DeviceIdentifier get_device_identifier(Address address)