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banan-os
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Kernel: Make all futexes shared 

Some stuff tries to use shared futexes so make them all shared. Private
futexes would be faster as they are process specific but supporting both
would need some reworks
This commit is contained in:
Bananymous 2025-08-21 02:56:17 +03:00
parent fb61cab70d
commit 350ae90bb6
2 changed files with 19 additions and 23 deletions
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8
kernel/include/kernel/Process.h
View File

@ -350,14 +350,6 @@ namespace Kernel
BAN::UniqPtr<PageTable> m_page_table;
BAN::RefPtr<TTY> m_controlling_terminal;
struct futex_t
{
ThreadBlocker blocker;
uint32_t waiters { 0 };
uint32_t to_wakeup { 0 };
};
BAN::HashMap<paddr_t, BAN::UniqPtr<futex_t>> m_futexes;
friend class Thread;
};

34
kernel/kernel/Process.cpp
View File

@ -37,6 +37,15 @@ namespace Kernel
static BAN::Vector<Process*> s_processes;
static RecursiveSpinLock s_process_lock;
struct futex_t
{
ThreadBlocker blocker;
uint32_t waiters { 0 };
uint32_t to_wakeup { 0 };
};
static BAN::HashMap<paddr_t, BAN::UniqPtr<futex_t>> s_futexes;
static Mutex s_futex_lock;
static void for_each_process(const BAN::Function<BAN::Iteration(Process&)>& callback)
{
SpinLockGuard _(s_process_lock);
@ -2720,17 +2729,12 @@ namespace Kernel
if (vaddr % 4)
return BAN::Error::from_errno(EINVAL);
const bool is_private = (op & FUTEX_PRIVATE);
const bool is_realtime = (op & FUTEX_REALTIME);
op &= ~(FUTEX_PRIVATE | FUTEX_REALTIME);
if (!is_private)
{
dwarnln("TODO: shared futex");
return BAN::Error::from_errno(ENOTSUP);
}
// TODO: possibly optimize private futexes?
LockGuard _(m_process_lock);
LockGuard _(s_futex_lock);
auto* buffer_region = TRY(validate_and_pin_pointer_access(addr, sizeof(uint32_t), false));
BAN::ScopeGuard pin_guard([&] { if (buffer_region) buffer_region->unpin(); });
@ -2761,20 +2765,20 @@ namespace Kernel
return SystemTimer::get().ns_since_boot() + (abs_ns - real_ns);
}());
auto it = m_futexes.find(paddr);
if (it == m_futexes.end())
it = TRY(m_futexes.emplace(paddr, TRY(BAN::UniqPtr<futex_t>::create())));
auto it = s_futexes.find(paddr);
if (it == s_futexes.end())
it = TRY(s_futexes.emplace(paddr, TRY(BAN::UniqPtr<futex_t>::create())));
futex_t* const futex = it->value.ptr();
futex->waiters++;
BAN::ScopeGuard _([futex, paddr, this] {
BAN::ScopeGuard _([futex, paddr] {
if (--futex->waiters == 0)
m_futexes.remove(paddr);
s_futexes.remove(paddr);
});
for (;;)
{
TRY(Thread::current().block_or_eintr_or_waketime_ns(futex->blocker, wake_time_ns, true, &m_process_lock));
TRY(Thread::current().block_or_eintr_or_waketime_ns(futex->blocker, wake_time_ns, true, &s_futex_lock));
if (BAN::atomic_load(*addr) == val || futex->to_wakeup == 0)
continue;
futex->to_wakeup--;
@ -2783,8 +2787,8 @@ namespace Kernel
}
case FUTEX_WAKE:
{
auto it = m_futexes.find(paddr);
if (it == m_futexes.end())
auto it = s_futexes.find(paddr);
if (it == s_futexes.end())
return 0;
futex_t* const futex = it->value.ptr();