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- /*
- * Copyright (c) 2020, The SerenityOS developers.
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions are met:
- *
- * 1. Redistributions of source code must retain the above copyright notice, this
- * list of conditions and the following disclaimer.
- *
- * 2. Redistributions in binary form must reproduce the above copyright notice,
- * this list of conditions and the following disclaimer in the documentation
- * and/or other materials provided with the distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
- * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
- * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
- * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
- * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
- * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
- */
- #include <Kernel/Debug.h>
- #include <Kernel/FutexQueue.h>
- #include <Kernel/Thread.h>
- namespace Kernel {
- bool FutexQueue::should_add_blocker(Thread::Blocker& b, void* data)
- {
- ASSERT(data != nullptr); // Thread that is requesting to be blocked
- ASSERT(m_lock.is_locked());
- ASSERT(b.blocker_type() == Thread::Blocker::Type::Futex);
- dbgln<FUTEXQUEUE_DEBUG>("FutexQueue @ {}: should block thread {}", this, *static_cast<Thread*>(data));
- return true;
- }
- u32 FutexQueue::wake_n_requeue(u32 wake_count, const Function<FutexQueue*()>& get_target_queue, u32 requeue_count, bool& is_empty, bool& is_empty_target)
- {
- is_empty_target = false;
- ScopedSpinLock lock(m_lock);
- dbgln<FUTEXQUEUE_DEBUG>("FutexQueue @ {}: wake_n_requeue({}, {})", this, wake_count, requeue_count);
- u32 did_wake = 0, did_requeue = 0;
- do_unblock([&](Thread::Blocker& b, void* data, bool& stop_iterating) {
- ASSERT(data);
- ASSERT(b.blocker_type() == Thread::Blocker::Type::Futex);
- auto& blocker = static_cast<Thread::FutexBlocker&>(b);
- dbgln<FUTEXQUEUE_DEBUG>("FutexQueue @ {}: wake_n_requeue unblocking {}", this, *static_cast<Thread*>(data));
- ASSERT(did_wake < wake_count);
- if (blocker.unblock()) {
- if (++did_wake >= wake_count)
- stop_iterating = true;
- return true;
- }
- return false;
- });
- is_empty = is_empty_locked();
- if (requeue_count > 0) {
- auto blockers_to_requeue = do_take_blockers(requeue_count);
- if (!blockers_to_requeue.is_empty()) {
- if (auto* target_futex_queue = get_target_queue()) {
- dbgln<FUTEXQUEUE_DEBUG>("FutexQueue @ {}: wake_n_requeue requeueing {} blockers to {}", this, blockers_to_requeue.size(), target_futex_queue);
- // While still holding m_lock, notify each blocker
- for (auto& info : blockers_to_requeue) {
- ASSERT(info.blocker->blocker_type() == Thread::Blocker::Type::Futex);
- auto& blocker = *static_cast<Thread::FutexBlocker*>(info.blocker);
- blocker.begin_requeue();
- }
- lock.unlock();
- did_requeue = blockers_to_requeue.size();
- ScopedSpinLock target_lock(target_futex_queue->m_lock);
- // Now that we have the lock of the target, append the blockers
- // and notify them that they completed the move
- for (auto& info : blockers_to_requeue) {
- ASSERT(info.blocker->blocker_type() == Thread::Blocker::Type::Futex);
- auto& blocker = *static_cast<Thread::FutexBlocker*>(info.blocker);
- blocker.finish_requeue(*target_futex_queue);
- }
- target_futex_queue->do_append_blockers(move(blockers_to_requeue));
- is_empty_target = target_futex_queue->is_empty_locked();
- } else {
- dbgln<FUTEXQUEUE_DEBUG>("FutexQueue @ {}: wake_n_requeue could not get target queue to requeue {} blockers", this, blockers_to_requeue.size());
- do_append_blockers(move(blockers_to_requeue));
- }
- }
- }
- return did_wake + did_requeue;
- }
- u32 FutexQueue::wake_n(u32 wake_count, const Optional<u32>& bitset, bool& is_empty)
- {
- if (wake_count == 0)
- return 0; // should we assert instead?
- ScopedSpinLock lock(m_lock);
- dbgln<FUTEXQUEUE_DEBUG>("FutexQueue @ {}: wake_n({})", this, wake_count);
- u32 did_wake = 0;
- do_unblock([&](Thread::Blocker& b, void* data, bool& stop_iterating) {
- ASSERT(data);
- ASSERT(b.blocker_type() == Thread::Blocker::Type::Futex);
- auto& blocker = static_cast<Thread::FutexBlocker&>(b);
- dbgln<FUTEXQUEUE_DEBUG>("FutexQueue @ {}: wake_n unblocking {}", this, *static_cast<Thread*>(data));
- ASSERT(did_wake < wake_count);
- if (bitset.has_value() ? blocker.unblock_bitset(bitset.value()) : blocker.unblock()) {
- if (++did_wake >= wake_count)
- stop_iterating = true;
- return true;
- }
- return false;
- });
- is_empty = is_empty_locked();
- return did_wake;
- }
- u32 FutexQueue::wake_all(bool& is_empty)
- {
- ScopedSpinLock lock(m_lock);
- dbgln<FUTEXQUEUE_DEBUG>("FutexQueue @ {}: wake_all", this);
- u32 did_wake = 0;
- do_unblock([&](Thread::Blocker& b, void* data, bool&) {
- ASSERT(data);
- ASSERT(b.blocker_type() == Thread::Blocker::Type::Futex);
- auto& blocker = static_cast<Thread::FutexBlocker&>(b);
- dbgln<FUTEXQUEUE_DEBUG>("FutexQueue @ {}: wake_all unblocking {}", this, *static_cast<Thread*>(data));
- if (blocker.unblock(true)) {
- did_wake++;
- return true;
- }
- return false;
- });
- is_empty = is_empty_locked();
- return did_wake;
- }
- }
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