ladybird/Kernel/ThreadBlockers.cpp
Andreas Kling 83b409083b Kernel: Stop using *LockRefPtr for ProcessGroup
Had to wrap Process::m_pg in a SpinlockProtected for this to be safe.
2023-04-04 10:33:42 +02:00

859 lines
27 KiB
C++

/*
* Copyright (c) 2020, the SerenityOS developers.
* Copyright (c) 2022, Idan Horowitz <idan.horowitz@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/BuiltinWrappers.h>
#include <Kernel/Debug.h>
#include <Kernel/FileSystem/OpenFileDescription.h>
#include <Kernel/Net/Socket.h>
#include <Kernel/Process.h>
#include <Kernel/Scheduler.h>
#include <Kernel/Thread.h>
namespace Kernel {
Thread::BlockTimeout::BlockTimeout(bool is_absolute, Time const* time, Time const* start_time, clockid_t clock_id)
: m_clock_id(clock_id)
, m_infinite(!time)
{
if (m_infinite)
return;
if (*time > Time::zero())
m_time = *time;
m_start_time = start_time ? *start_time : TimeManagement::the().current_time(clock_id);
if (!is_absolute)
m_time += m_start_time;
}
bool Thread::Blocker::add_to_blocker_set(Thread::BlockerSet& blocker_set, void* data)
{
VERIFY(!m_blocker_set);
if (blocker_set.add_blocker(*this, data)) {
m_blocker_set = &blocker_set;
return true;
}
return false;
}
Thread::Blocker::~Blocker() = default;
void Thread::Blocker::finalize()
{
if (m_blocker_set)
m_blocker_set->remove_blocker(*this);
}
bool Thread::Blocker::setup_blocker()
{
return true;
}
void Thread::Blocker::begin_blocking(Badge<Thread>)
{
SpinlockLocker lock(m_lock);
VERIFY(!m_is_blocking);
m_is_blocking = true;
}
auto Thread::Blocker::end_blocking(Badge<Thread>, bool did_timeout) -> BlockResult
{
SpinlockLocker lock(m_lock);
// if m_is_blocking is false here, some thread forced to
// unblock us when we get here. This is only called from the
// thread that was blocked.
VERIFY(Thread::current() == m_thread);
m_is_blocking = false;
was_unblocked(did_timeout);
return block_result();
}
Thread::JoinBlocker::JoinBlocker(Thread& joinee, ErrorOr<void>& try_join_result, void*& joinee_exit_value)
: m_joinee(joinee)
, m_joinee_exit_value(joinee_exit_value)
, m_try_join_result(try_join_result)
{
}
bool Thread::JoinBlocker::setup_blocker()
{
// We need to hold our lock to avoid a race where try_join succeeds
// but the joinee is joining immediately
SpinlockLocker lock(m_lock);
bool should_block = true;
m_try_join_result = m_joinee->try_join([&]() {
if (!add_to_blocker_set(m_joinee->m_join_blocker_set))
should_block = false;
});
if (m_try_join_result.is_error())
return false;
return should_block;
}
void Thread::JoinBlocker::will_unblock_immediately_without_blocking(UnblockImmediatelyReason reason)
{
// If we should have blocked but got here it must have been that the
// timeout was already in the past. So we need to ask the BlockerSet
// to supply us the information. We cannot hold the lock as unblock
// could be called by the BlockerSet at any time!
if (reason == UnblockImmediatelyReason::TimeoutInThePast) {
m_joinee->m_join_blocker_set.try_unblock(*this);
}
}
bool Thread::JoinBlocker::unblock(void* value, bool from_add_blocker)
{
{
SpinlockLocker lock(m_lock);
if (m_did_unblock)
return false;
m_did_unblock = true;
m_joinee_exit_value = value;
do_set_interrupted_by_death();
}
if (!from_add_blocker)
unblock_from_blocker();
return true;
}
Thread::WaitQueueBlocker::WaitQueueBlocker(WaitQueue& wait_queue, StringView block_reason)
: m_wait_queue(wait_queue)
, m_block_reason(block_reason)
{
}
bool Thread::WaitQueueBlocker::setup_blocker()
{
return add_to_blocker_set(m_wait_queue);
}
Thread::WaitQueueBlocker::~WaitQueueBlocker() = default;
bool Thread::WaitQueueBlocker::unblock()
{
{
SpinlockLocker lock(m_lock);
if (m_did_unblock)
return false;
m_did_unblock = true;
}
unblock_from_blocker();
return true;
}
Thread::FutexBlocker::FutexBlocker(FutexQueue& futex_queue, u32 bitset)
: m_futex_queue(futex_queue)
, m_bitset(bitset)
{
}
bool Thread::FutexBlocker::setup_blocker()
{
return add_to_blocker_set(m_futex_queue);
}
Thread::FutexBlocker::~FutexBlocker() = default;
void Thread::FutexBlocker::finish_requeue(FutexQueue& futex_queue)
{
VERIFY(m_lock.is_locked_by_current_processor());
set_blocker_set_raw_locked(&futex_queue);
// We can now release the lock
m_lock.unlock(m_previous_interrupts_state);
}
bool Thread::FutexBlocker::unblock_bitset(u32 bitset)
{
{
SpinlockLocker lock(m_lock);
if (m_did_unblock || (bitset != FUTEX_BITSET_MATCH_ANY && (m_bitset & bitset) == 0))
return false;
m_did_unblock = true;
}
unblock_from_blocker();
return true;
}
bool Thread::FutexBlocker::unblock(bool force)
{
{
SpinlockLocker lock(m_lock);
if (m_did_unblock)
return force;
m_did_unblock = true;
}
unblock_from_blocker();
return true;
}
Thread::OpenFileDescriptionBlocker::OpenFileDescriptionBlocker(OpenFileDescription& description, BlockFlags flags, BlockFlags& unblocked_flags)
: m_blocked_description(description)
, m_flags(flags)
, m_unblocked_flags(unblocked_flags)
{
}
bool Thread::OpenFileDescriptionBlocker::setup_blocker()
{
m_unblocked_flags = BlockFlags::None;
return add_to_blocker_set(m_blocked_description->blocker_set());
}
bool Thread::OpenFileDescriptionBlocker::unblock_if_conditions_are_met(bool from_add_blocker, void*)
{
auto unblock_flags = m_blocked_description->should_unblock(m_flags);
if (unblock_flags == BlockFlags::None)
return false;
{
SpinlockLocker lock(m_lock);
if (m_did_unblock)
return false;
m_did_unblock = true;
m_unblocked_flags = unblock_flags;
}
if (!from_add_blocker)
unblock_from_blocker();
return true;
}
void Thread::OpenFileDescriptionBlocker::will_unblock_immediately_without_blocking(UnblockImmediatelyReason reason)
{
if (reason == UnblockImmediatelyReason::UnblockConditionAlreadyMet)
return;
// If we should have blocked but got here it must have been that the
// timeout was already in the past. So we need to ask the BlockerSet
// to supply us the information. We cannot hold the lock as unblock
// could be called by the BlockerSet at any time!
VERIFY(reason == UnblockImmediatelyReason::TimeoutInThePast);
// Just call unblock_if_conditions_are_met here because we will query the file description
// for the data and don't need any input from the FileBlockerSet.
// However, it's possible that if timeout_in_past is true then FileBlockerSet
// may call us at any given time, so our call to unblock here may fail.
// Either way, unblock will be called at least once, which provides
// all the data we need.
unblock_if_conditions_are_met(false, nullptr);
}
OpenFileDescription const& Thread::OpenFileDescriptionBlocker::blocked_description() const
{
return m_blocked_description;
}
Thread::AcceptBlocker::AcceptBlocker(OpenFileDescription& description, BlockFlags& unblocked_flags)
: OpenFileDescriptionBlocker(description, BlockFlags::Accept | BlockFlags::Exception, unblocked_flags)
{
}
Thread::ConnectBlocker::ConnectBlocker(OpenFileDescription& description, BlockFlags& unblocked_flags)
: OpenFileDescriptionBlocker(description, BlockFlags::Connect | BlockFlags::Exception, unblocked_flags)
{
}
Thread::WriteBlocker::WriteBlocker(OpenFileDescription& description, BlockFlags& unblocked_flags)
: OpenFileDescriptionBlocker(description, BlockFlags::Write | BlockFlags::Exception, unblocked_flags)
{
}
auto Thread::WriteBlocker::override_timeout(BlockTimeout const& timeout) -> BlockTimeout const&
{
auto const& description = blocked_description();
if (description.is_socket()) {
auto const& socket = *description.socket();
if (socket.has_send_timeout()) {
Time send_timeout = socket.send_timeout();
m_timeout = BlockTimeout(false, &send_timeout, timeout.start_time(), timeout.clock_id());
if (timeout.is_infinite() || (!m_timeout.is_infinite() && m_timeout.absolute_time() < timeout.absolute_time()))
return m_timeout;
}
}
return timeout;
}
Thread::ReadBlocker::ReadBlocker(OpenFileDescription& description, BlockFlags& unblocked_flags)
: OpenFileDescriptionBlocker(description, BlockFlags::Read | BlockFlags::Exception, unblocked_flags)
{
}
auto Thread::ReadBlocker::override_timeout(BlockTimeout const& timeout) -> BlockTimeout const&
{
auto const& description = blocked_description();
if (description.is_socket()) {
auto const& socket = *description.socket();
if (socket.has_receive_timeout()) {
Time receive_timeout = socket.receive_timeout();
m_timeout = BlockTimeout(false, &receive_timeout, timeout.start_time(), timeout.clock_id());
if (timeout.is_infinite() || (!m_timeout.is_infinite() && m_timeout.absolute_time() < timeout.absolute_time()))
return m_timeout;
}
}
return timeout;
}
Thread::SleepBlocker::SleepBlocker(BlockTimeout const& deadline, Time* remaining)
: m_deadline(deadline)
, m_remaining(remaining)
{
}
auto Thread::SleepBlocker::override_timeout(BlockTimeout const& timeout) -> BlockTimeout const&
{
VERIFY(timeout.is_infinite()); // A timeout should not be provided
// To simplify things only use the sleep deadline.
return m_deadline;
}
void Thread::SleepBlocker::will_unblock_immediately_without_blocking(UnblockImmediatelyReason reason)
{
// SleepBlocker::should_block should always return true, so timeout
// in the past is the only valid case when this function is called
VERIFY(reason == UnblockImmediatelyReason::TimeoutInThePast);
calculate_remaining();
}
void Thread::SleepBlocker::was_unblocked(bool did_timeout)
{
Blocker::was_unblocked(did_timeout);
calculate_remaining();
}
void Thread::SleepBlocker::calculate_remaining()
{
if (!m_remaining)
return;
auto time_now = TimeManagement::the().current_time(m_deadline.clock_id());
if (time_now < m_deadline.absolute_time())
*m_remaining = m_deadline.absolute_time() - time_now;
else
*m_remaining = {};
}
Thread::BlockResult Thread::SleepBlocker::block_result()
{
auto result = Blocker::block_result();
if (result == Thread::BlockResult::InterruptedByTimeout)
return Thread::BlockResult::WokeNormally;
return result;
}
Thread::SelectBlocker::SelectBlocker(FDVector& fds)
: m_fds(fds)
{
}
bool Thread::SelectBlocker::setup_blocker()
{
bool should_block = true;
for (auto& fd_entry : m_fds) {
fd_entry.unblocked_flags = FileBlocker::BlockFlags::None;
if (!should_block)
continue;
if (!fd_entry.description) {
should_block = false;
continue;
}
if (!fd_entry.description->blocker_set().add_blocker(*this, &fd_entry))
should_block = false;
}
return should_block;
}
Thread::SelectBlocker::~SelectBlocker() = default;
void Thread::SelectBlocker::finalize()
{
Thread::FileBlocker::finalize();
for (auto& fd_entry : m_fds) {
if (fd_entry.description)
fd_entry.description->blocker_set().remove_blocker(*this);
}
}
void Thread::SelectBlocker::will_unblock_immediately_without_blocking(UnblockImmediatelyReason reason)
{
SpinlockLocker lock(m_lock);
if (m_did_unblock)
return;
m_did_unblock = true;
if (reason == UnblockImmediatelyReason::UnblockConditionAlreadyMet) {
auto count = collect_unblocked_flags();
VERIFY(count > 0);
}
}
bool Thread::SelectBlocker::unblock_if_conditions_are_met(bool from_add_blocker, void* data)
{
VERIFY(data); // data is a pointer to an entry in the m_fds vector
auto& fd_info = *static_cast<FDInfo*>(data);
{
SpinlockLocker lock(m_lock);
if (m_did_unblock)
return false;
VERIFY(fd_info.description);
auto unblock_flags = fd_info.description->should_unblock(fd_info.block_flags);
if (unblock_flags == BlockFlags::None)
return false;
m_did_unblock = true;
// We need to store unblock_flags here, otherwise someone else
// affecting this file descriptor could change the information
// between now and when was_unblocked is called!
fd_info.unblocked_flags = unblock_flags;
}
// Only do this once for the first one
if (!from_add_blocker)
unblock_from_blocker();
return true;
}
size_t Thread::SelectBlocker::collect_unblocked_flags()
{
size_t count = 0;
for (auto& fd_entry : m_fds) {
VERIFY(fd_entry.block_flags != FileBlocker::BlockFlags::None);
if (!fd_entry.description) {
count++;
continue;
}
// unblock will have set at least the first descriptor's unblock
// flags that triggered the unblock. Make sure we don't discard that
// information as it may have changed by now!
if (fd_entry.unblocked_flags == FileBlocker::BlockFlags::None)
fd_entry.unblocked_flags = fd_entry.description->should_unblock(fd_entry.block_flags);
if (fd_entry.unblocked_flags != FileBlocker::BlockFlags::None)
count++;
}
return count;
}
void Thread::SelectBlocker::was_unblocked(bool did_timeout)
{
Blocker::was_unblocked(did_timeout);
if (!did_timeout && !was_interrupted()) {
{
SpinlockLocker lock(m_lock);
VERIFY(m_did_unblock);
}
size_t count = collect_unblocked_flags();
// If we were blocked and didn't time out, we should have at least one unblocked fd!
VERIFY(count > 0);
}
}
Thread::SignalBlocker::SignalBlocker(sigset_t pending_set, siginfo_t& result)
: m_pending_set(pending_set)
, m_result(result)
{
}
void Thread::SignalBlocker::will_unblock_immediately_without_blocking(UnblockImmediatelyReason unblock_immediately_reason)
{
if (unblock_immediately_reason != UnblockImmediatelyReason::TimeoutInThePast)
return;
// If the specified timeout is 0 the caller is simply trying to poll once for pending signals,
// so simply calling check_pending_signals should populate the requested information.
check_pending_signals(false);
}
bool Thread::SignalBlocker::setup_blocker()
{
return add_to_blocker_set(thread().m_signal_blocker_set);
}
bool Thread::SignalBlocker::check_pending_signals(bool from_add_blocker)
{
{
SpinlockLocker lock(m_lock);
if (m_did_unblock)
return false;
auto pending_signals = thread().pending_signals() & m_pending_set;
// Also unblock if we have just "handled" that signal and are in the procecss
// of running their signal handler (i.e. we just unmarked the signal as pending).
if (thread().m_currently_handled_signal)
pending_signals |= (1 << (thread().m_currently_handled_signal - 1)) & m_pending_set;
auto matching_pending_signal = bit_scan_forward(pending_signals);
if (matching_pending_signal == 0)
return false;
m_did_unblock = true;
m_result = {};
m_result.si_signo = matching_pending_signal;
m_result.si_code = 0; // FIXME: How can we determine this?
}
if (!from_add_blocker)
unblock_from_blocker();
return true;
}
Thread::WaitBlockerSet::ProcessBlockInfo::ProcessBlockInfo(NonnullRefPtr<Process>&& process, WaitBlocker::UnblockFlags flags, u8 signal)
: process(move(process))
, flags(flags)
, signal(signal)
{
}
Thread::WaitBlockerSet::ProcessBlockInfo::~ProcessBlockInfo() = default;
void Thread::WaitBlockerSet::try_unblock(Thread::WaitBlocker& blocker)
{
SpinlockLocker lock(m_lock);
// We if we have any processes pending
for (size_t i = 0; i < m_processes.size(); i++) {
auto& info = m_processes[i];
// We need to call unblock as if we were called from add_blocker
// so that we don't trigger a context switch by yielding!
if (info.was_waited && blocker.is_wait())
continue; // This state was already waited on, do not unblock
if (blocker.unblock(info.process, info.flags, info.signal, true)) {
if (blocker.is_wait()) {
if (info.flags == Thread::WaitBlocker::UnblockFlags::Terminated) {
m_processes.remove(i);
dbgln_if(WAITBLOCK_DEBUG, "WaitBlockerSet[{}] terminated, remove {}", m_process, *info.process);
} else {
dbgln_if(WAITBLOCK_DEBUG, "WaitBlockerSet[{}] terminated, mark as waited {}", m_process, *info.process);
info.was_waited = true;
}
}
break;
}
}
}
void Thread::WaitBlockerSet::disowned_by_waiter(Process& process)
{
SpinlockLocker lock(m_lock);
if (m_finalized)
return;
for (size_t i = 0; i < m_processes.size();) {
auto& info = m_processes[i];
if (info.process == &process) {
unblock_all_blockers_whose_conditions_are_met_locked([&](Blocker& b, void*, bool&) {
VERIFY(b.blocker_type() == Blocker::Type::Wait);
auto& blocker = static_cast<WaitBlocker&>(b);
bool did_unblock = blocker.unblock(info.process, WaitBlocker::UnblockFlags::Disowned, 0, false);
VERIFY(did_unblock); // disowning must unblock everyone
return true;
});
dbgln_if(WAITBLOCK_DEBUG, "WaitBlockerSet[{}] disowned {}", m_process, *info.process);
m_processes.remove(i);
continue;
}
i++;
}
}
bool Thread::WaitBlockerSet::unblock(Process& process, WaitBlocker::UnblockFlags flags, u8 signal)
{
VERIFY(flags != WaitBlocker::UnblockFlags::Disowned);
bool did_unblock_any = false;
bool did_wait = false;
bool was_waited_already = false;
SpinlockLocker lock(m_lock);
if (m_finalized)
return false;
if (flags != WaitBlocker::UnblockFlags::Terminated) {
// First check if this state was already waited on
for (auto& info : m_processes) {
if (info.process == &process) {
was_waited_already = info.was_waited;
break;
}
}
}
unblock_all_blockers_whose_conditions_are_met_locked([&](Blocker& b, void*, bool&) {
VERIFY(b.blocker_type() == Blocker::Type::Wait);
auto& blocker = static_cast<WaitBlocker&>(b);
if (was_waited_already && blocker.is_wait())
return false; // This state was already waited on, do not unblock
if (blocker.unblock(process, flags, signal, false)) {
did_wait |= blocker.is_wait(); // anyone requesting a wait
did_unblock_any = true;
return true;
}
return false;
});
// If no one has waited (yet), or this wasn't a wait, or if it's anything other than
// UnblockFlags::Terminated then add it to your list
if (!did_unblock_any || !did_wait || flags != WaitBlocker::UnblockFlags::Terminated) {
bool updated_existing = false;
for (auto& info : m_processes) {
if (info.process == &process) {
VERIFY(info.flags != WaitBlocker::UnblockFlags::Terminated);
info.flags = flags;
info.signal = signal;
info.was_waited = did_wait;
dbgln_if(WAITBLOCK_DEBUG, "WaitBlockerSet[{}] update {} flags={}, waited={}", m_process, process, (int)flags, info.was_waited);
updated_existing = true;
break;
}
}
if (!updated_existing) {
dbgln_if(WAITBLOCK_DEBUG, "WaitBlockerSet[{}] add {} flags: {}", m_process, process, (int)flags);
m_processes.append(ProcessBlockInfo(process, flags, signal));
}
}
return did_unblock_any;
}
bool Thread::WaitBlockerSet::should_add_blocker(Blocker& b, void*)
{
// NOTE: m_lock is held already!
if (m_finalized)
return false;
VERIFY(b.blocker_type() == Blocker::Type::Wait);
auto& blocker = static_cast<WaitBlocker&>(b);
// See if we can match any process immediately
for (size_t i = 0; i < m_processes.size(); i++) {
auto& info = m_processes[i];
if (blocker.unblock(info.process, info.flags, info.signal, true)) {
// Only remove the entry if UnblockFlags::Terminated
if (info.flags == Thread::WaitBlocker::UnblockFlags::Terminated && blocker.is_wait())
m_processes.remove(i);
return false;
}
}
return true;
}
void Thread::WaitBlockerSet::finalize()
{
SpinlockLocker lock(m_lock);
VERIFY(!m_finalized);
m_finalized = true;
// Clear the list of threads here so we can drop the references to them
m_processes.clear();
// NOTE: Kernel processes don't have a leaked ref on them.
if (!m_process.is_kernel_process()) {
// No more waiters, drop the last reference immediately. This may
// cause us to be destructed ourselves!
VERIFY(m_process.ref_count() > 0);
m_process.unref();
}
}
Thread::WaitBlocker::WaitBlocker(int wait_options, Variant<Empty, NonnullRefPtr<Process>, NonnullRefPtr<ProcessGroup>> waitee, ErrorOr<siginfo_t>& result)
: m_wait_options(wait_options)
, m_result(result)
, m_waitee(move(waitee))
{
}
bool Thread::WaitBlocker::setup_blocker()
{
if (m_wait_options & WNOHANG)
return false;
return add_to_blocker_set(Process::current().wait_blocker_set());
}
void Thread::WaitBlocker::will_unblock_immediately_without_blocking(UnblockImmediatelyReason)
{
Process::current().wait_blocker_set().try_unblock(*this);
}
void Thread::WaitBlocker::was_unblocked(bool)
{
bool got_sigchld, try_unblock;
{
SpinlockLocker lock(m_lock);
try_unblock = !m_did_unblock;
got_sigchld = m_got_sigchild;
}
if (try_unblock)
Process::current().wait_blocker_set().try_unblock(*this);
// If we were interrupted by SIGCHLD (which gets special handling
// here) we're not going to return with EINTR. But we're going to
// deliver SIGCHLD (only) here.
auto* current_thread = Thread::current();
if (got_sigchld && current_thread->state() != State::Stopped)
current_thread->try_dispatch_one_pending_signal(SIGCHLD);
}
void Thread::WaitBlocker::do_was_disowned()
{
VERIFY(!m_did_unblock);
m_did_unblock = true;
m_result = ECHILD;
}
void Thread::WaitBlocker::do_set_result(siginfo_t const& result)
{
VERIFY(!m_did_unblock);
m_did_unblock = true;
m_result = result;
if (do_get_interrupted_by_signal() == SIGCHLD) {
// This makes it so that wait() will return normally despite the
// fact that SIGCHLD was delivered. Calling do_clear_interrupted_by_signal
// will disable dispatching signals in Thread::block and prevent
// it from returning with EINTR. We will then manually dispatch
// SIGCHLD (and only SIGCHLD) in was_unblocked.
m_got_sigchild = true;
do_clear_interrupted_by_signal();
}
}
bool Thread::WaitBlocker::unblock(Process& process, UnblockFlags flags, u8 signal, bool from_add_blocker)
{
VERIFY(flags != UnblockFlags::Terminated || signal == 0); // signal argument should be ignored for Terminated
bool do_not_unblock = m_waitee.visit(
[&](NonnullRefPtr<Process> const& waitee_process) {
return &process != waitee_process;
},
[&](NonnullRefPtr<ProcessGroup> const& waitee_process_group) {
return waitee_process_group->pgid() != process.pgid();
},
[&](Empty const&) {
// Generic waiter won't be unblocked by disown
return flags == UnblockFlags::Disowned;
});
if (do_not_unblock)
return false;
switch (flags) {
case UnblockFlags::Terminated:
if (!(m_wait_options & WEXITED))
return false;
break;
case UnblockFlags::Stopped:
if (!(m_wait_options & WSTOPPED))
return false;
if (!(m_wait_options & WUNTRACED) && !process.is_traced())
return false;
break;
case UnblockFlags::Continued:
if (!(m_wait_options & WCONTINUED))
return false;
if (!(m_wait_options & WUNTRACED) && !process.is_traced())
return false;
break;
case UnblockFlags::Disowned:
SpinlockLocker lock(m_lock);
// Disowning must unblock anyone waiting for this process explicitly
if (!m_did_unblock)
do_was_disowned();
return true;
}
if (flags == UnblockFlags::Terminated) {
VERIFY(process.is_dead());
SpinlockLocker lock(m_lock);
if (m_did_unblock)
return false;
// Up until this point, this function may have been called
// more than once!
do_set_result(process.wait_info());
} else {
siginfo_t siginfo {};
{
SpinlockLocker lock(g_scheduler_lock);
auto credentials = process.credentials();
// We need to gather the information before we release the scheduler lock!
siginfo.si_signo = SIGCHLD;
siginfo.si_pid = process.pid().value();
siginfo.si_uid = credentials->uid().value();
siginfo.si_status = signal;
switch (flags) {
case UnblockFlags::Terminated:
case UnblockFlags::Disowned:
VERIFY_NOT_REACHED();
case UnblockFlags::Stopped:
siginfo.si_code = CLD_STOPPED;
break;
case UnblockFlags::Continued:
siginfo.si_code = CLD_CONTINUED;
break;
}
}
SpinlockLocker lock(m_lock);
if (m_did_unblock)
return false;
// Up until this point, this function may have been called
// more than once!
do_set_result(siginfo);
}
if (!from_add_blocker) {
// Only call unblock if we weren't called from within add_to_blocker_set!
VERIFY(flags != UnblockFlags::Disowned);
unblock_from_blocker();
}
// Because this may be called from add_blocker, in which case we should
// not be actually trying to unblock the thread (because it hasn't actually
// been blocked yet), we need to return true anyway
return true;
}
Thread::FlockBlocker::FlockBlocker(NonnullRefPtr<Inode> inode, flock const& flock)
: m_inode(move(inode))
, m_flock(flock)
{
}
void Thread::FlockBlocker::will_unblock_immediately_without_blocking(UnblockImmediatelyReason reason)
{
VERIFY(reason == UnblockImmediatelyReason::UnblockConditionAlreadyMet);
}
bool Thread::FlockBlocker::setup_blocker()
{
return add_to_blocker_set(m_inode->flock_blocker_set());
}
bool Thread::FlockBlocker::try_unblock(bool from_add_blocker)
{
if (!m_inode->can_apply_flock(m_flock))
return false;
{
SpinlockLocker lock(m_lock);
if (m_did_unblock)
return false;
m_did_unblock = true;
}
if (!from_add_blocker)
unblock_from_blocker();
return true;
}
}