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Kernel: Move Blocker setup out from constructors into setup_blocker()

Browse source 
Instead of registering with blocker sets and whatnot in the various
Blocker subclass constructors, this patch moves such initialization
to a separate setup_blocker() virtual.

setup_blocker() returns false if there's no need to actually block
the thread. This allows us to bail earlier in Thread::block().
This commit is contained in:
Andreas Kling 2021-08-24 12:14:14 +02:00
parent c108c8ff24
commit 82c3cc4640
5 changed files with 92 additions and 39 deletions
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78
Kernel/ThreadBlockers.cpp
View file

@ -45,6 +45,11 @@ Thread::Blocker::~Blocker()
m_blocker_set->remove_blocker(*this);
}
bool Thread::Blocker::setup_blocker()
{
return true;
}
void Thread::Blocker::begin_blocking(Badge<Thread>)
{
SpinlockLocker lock(m_lock);
@ -68,19 +73,23 @@ auto Thread::Blocker::end_blocking(Badge<Thread>, bool did_timeout) -> BlockResu
Thread::JoinBlocker::JoinBlocker(Thread& joinee, KResult& try_join_result, void*& joinee_exit_value)
: m_joinee(joinee)
, m_joinee_exit_value(joinee_exit_value)
, m_try_join_result(try_join_result)
{
{
// We need to hold our lock to avoid a race where try_join succeeds
// but the joinee is joining immediately
SpinlockLocker lock(m_lock);
try_join_result = joinee.try_join([&]() {
if (!add_to_blocker_set(joinee.m_join_blocker_set))
m_should_block = false;
});
m_join_error = try_join_result.is_error();
if (m_join_error)
}
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);
m_try_join_result = m_joinee->try_join([&]() {
if (!add_to_blocker_set(m_joinee->m_join_blocker_set))
m_should_block = false;
}
});
m_join_error = m_try_join_result.is_error();
if (m_join_error)
m_should_block = false;
return m_should_block;
}
void Thread::JoinBlocker::will_unblock_immediately_without_blocking(UnblockImmediatelyReason reason)
@ -114,10 +123,16 @@ bool Thread::JoinBlocker::unblock(void* value, bool from_add_blocker)
}
Thread::WaitQueueBlocker::WaitQueueBlocker(WaitQueue& wait_queue, StringView block_reason)
: m_block_reason(block_reason)
: m_wait_queue(wait_queue)
, m_block_reason(block_reason)
{
if (!add_to_blocker_set(wait_queue))
}
bool Thread::WaitQueueBlocker::setup_blocker()
{
if (!add_to_blocker_set(m_wait_queue))
m_should_block = false;
return m_should_block;
}
Thread::WaitQueueBlocker::~WaitQueueBlocker()
@ -138,10 +153,16 @@ bool Thread::WaitQueueBlocker::unblock()
}
Thread::FutexBlocker::FutexBlocker(FutexQueue& futex_queue, u32 bitset)
: m_bitset(bitset)
: m_futex_queue(futex_queue)
, m_bitset(bitset)
{
if (!add_to_blocker_set(futex_queue))
}
bool Thread::FutexBlocker::setup_blocker()
{
if (!add_to_blocker_set(m_futex_queue))
m_should_block = false;
return m_should_block;
}
Thread::FutexBlocker::~FutexBlocker()
@ -187,10 +208,15 @@ Thread::FileDescriptionBlocker::FileDescriptionBlocker(FileDescription& descript
: m_blocked_description(description)
, m_flags(flags)
, m_unblocked_flags(unblocked_flags)
{
}
bool Thread::FileDescriptionBlocker::setup_blocker()
{
m_unblocked_flags = BlockFlags::None;
if (!add_to_blocker_set(description.blocker_set()))
if (!add_to_blocker_set(m_blocked_description->blocker_set()))
m_should_block = false;
return m_should_block;
}
bool Thread::FileDescriptionBlocker::unblock(bool from_add_blocker, void*)
@ -337,6 +363,10 @@ Thread::BlockResult Thread::SleepBlocker::block_result()
Thread::SelectBlocker::SelectBlocker(FDVector& fds)
: m_fds(fds)
{
}
bool Thread::SelectBlocker::setup_blocker()
{
for (auto& fd_entry : m_fds) {
fd_entry.unblocked_flags = FileBlocker::BlockFlags::None;
@ -346,6 +376,7 @@ Thread::SelectBlocker::SelectBlocker(FDVector& fds)
if (!fd_entry.description->blocker_set().add_blocker(*this, &fd_entry))
m_should_block = false;
}
return m_should_block;
}
Thread::SelectBlocker::~SelectBlocker()
@ -590,7 +621,11 @@ Thread::WaitBlocker::WaitBlocker(int wait_options, idtype_t id_type, pid_t id, K
, m_result(result)
, m_should_block(!(m_wait_options & WNOHANG))
{
switch (id_type) {
}
bool Thread::WaitBlocker::setup_blocker()
{
switch (m_id_type) {
case P_PID: {
m_waitee = Process::from_pid(m_waitee_id);
if (!m_waitee || m_waitee->ppid() != Process::current().pid()) {
@ -613,11 +648,16 @@ Thread::WaitBlocker::WaitBlocker(int wait_options, idtype_t id_type, pid_t id, K
VERIFY_NOT_REACHED();
}
if (m_error)
return false;
if (m_wait_options & WNOHANG)
return false;
// NOTE: unblock may be called within add_to_blocker_set, in which
// case it means that we already have a match without having to block.
// In that case add_to_blocker_set will return false.
if (m_error || !add_to_blocker_set(Process::current().wait_blocker_set()))
m_should_block = false;
return add_to_blocker_set(Process::current().wait_blocker_set());
}
void Thread::WaitBlocker::will_unblock_immediately_without_blocking(UnblockImmediatelyReason reason)