ladybird/Kernel/Locking/LockRank.cpp
Brian Gianforcaro 066b0590ec Kernel/Locking: Add lock rank tracking per thread to find deadlocks
This change adds a static lock hierarchy / ranking to the Kernel with
the goal of reducing / finding deadlocks when running with SMP enabled.

We have seen quite a few lock ordering deadlocks (locks taken in a
different order, on two different code paths). As we properly annotate
locks in the system, then these facilities will find these locking
protocol violations automatically

The `LockRank` enum documents the various locks in the system and their
rank. The implementation guarantees that a thread holding one or more
locks of a lower rank cannot acquire an additional lock with rank that
is greater or equal to any of the currently held locks.
2021-09-07 13:16:01 +02:00

29 lines
666 B
C++

/*
* Copyright (c) 2021, Brian Gianforcaro <bgianf@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/Locking/LockRank.h>
#include <Kernel/Thread.h>
// Note: These stubs can't be in LockRank.h as that would create
// a cyclic dependency in the header include graph of the Kernel.
namespace Kernel {
void track_lock_acquire(LockRank rank)
{
auto thread = Thread::current();
if (thread && !thread->is_crashing())
thread->track_lock_acquire(rank);
}
void track_lock_release(LockRank rank)
{
auto thread = Thread::current();
if (thread && !thread->is_crashing())
thread->track_lock_release(rank);
}
}