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https://github.com/RGBCube/serenity
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259bfe05b1
This is intended to reflect the POSIX sched_setparam API, which has some cryptic language (https://pubs.opengroup.org/onlinepubs/9699919799/functions/V2_chap02.html#tag_15_08_04_01 ) that as far as I can tell implies we should prioritize process scheduling policies over thread scheduling policies. Technically this means that a process must have its own sets of policies that are considered first by the scheduler, but it seems unlikely anyone relies on this behavior in practice. So we just override all thread's policies, making them (at least before calls to pthread_setschedparam) behave exactly like specified on the surface.
117 lines
3.9 KiB
C++
117 lines
3.9 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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* Copyright (c) 2022, kleines Filmröllchen <filmroellchen@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/API/Syscall.h>
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#include <Kernel/Process.h>
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#include <Kernel/Scheduler.h>
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namespace Kernel {
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ErrorOr<FlatPtr> Process::sys$yield()
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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TRY(require_promise(Pledge::stdio));
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Thread::current()->yield_without_releasing_big_lock();
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return 0;
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}
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ErrorOr<NonnullRefPtr<Thread>> Process::get_thread_from_pid_or_tid(pid_t pid_or_tid, Syscall::SchedulerParametersMode mode)
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{
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VERIFY(g_scheduler_lock.is_locked_by_current_processor());
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Thread* peer;
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switch (mode) {
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case Syscall::SchedulerParametersMode::Thread: {
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peer = Thread::current();
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if (pid_or_tid != 0)
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peer = Thread::from_tid(pid_or_tid);
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// Only superuser can access other processes' threads.
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if (!credentials()->is_superuser() && peer && &peer->process() != this)
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return EPERM;
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break;
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}
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case Syscall::SchedulerParametersMode::Process: {
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auto* searched_process = this;
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if (pid_or_tid != 0)
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searched_process = Process::from_pid(pid_or_tid);
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if (searched_process == nullptr)
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return ESRCH;
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auto pid = searched_process->pid().value();
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// Main thread has tid == pid
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this->thread_list().for_each([&](auto& thread) {
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if (thread.tid().value() == pid)
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peer = &thread;
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});
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break;
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}
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default:
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VERIFY_NOT_REACHED();
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}
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if (!peer)
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return ESRCH;
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return NonnullRefPtr<Thread> { *peer };
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}
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ErrorOr<FlatPtr> Process::sys$scheduler_set_parameters(Userspace<Syscall::SC_scheduler_parameters_params const*> user_param)
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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TRY(require_promise(Pledge::proc));
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auto parameters = TRY(copy_typed_from_user(user_param));
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if (parameters.parameters.sched_priority < THREAD_PRIORITY_MIN || parameters.parameters.sched_priority > THREAD_PRIORITY_MAX)
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return EINVAL;
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SpinlockLocker lock(g_scheduler_lock);
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auto peer = TRY(get_thread_from_pid_or_tid(parameters.pid_or_tid, parameters.mode));
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auto credentials = this->credentials();
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auto peer_credentials = peer->process().credentials();
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if (!credentials->is_superuser() && credentials->euid() != peer_credentials->uid() && credentials->uid() != peer_credentials->uid())
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return EPERM;
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peer->set_priority((u32)parameters.parameters.sched_priority);
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// POSIX says that process scheduling parameters have precedence over thread scheduling parameters.
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// We don't track them separately, so overwrite the thread scheduling settings manually for now.
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if (parameters.mode == Syscall::SchedulerParametersMode::Process) {
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peer->process().for_each_thread([&](auto& thread) {
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thread.set_priority((u32)parameters.parameters.sched_priority);
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});
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}
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return 0;
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}
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ErrorOr<FlatPtr> Process::sys$scheduler_get_parameters(Userspace<Syscall::SC_scheduler_parameters_params*> user_param)
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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TRY(require_promise(Pledge::proc));
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Syscall::SC_scheduler_parameters_params parameters;
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TRY(copy_from_user(¶meters, user_param));
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int priority;
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{
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SpinlockLocker lock(g_scheduler_lock);
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auto peer = TRY(get_thread_from_pid_or_tid(parameters.pid_or_tid, parameters.mode));
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auto credentials = this->credentials();
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auto peer_credentials = peer->process().credentials();
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if (!credentials->is_superuser() && credentials->euid() != peer_credentials->uid() && credentials->uid() != peer_credentials->uid())
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return EPERM;
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priority = (int)peer->priority();
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}
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parameters.parameters.sched_priority = priority;
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TRY(copy_to_user(user_param, ¶meters));
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return 0;
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}
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}
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