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Kernel: Make Thread refcounted

Browse source 
Similar to Process, we need to make Thread refcounted. This will solve
problems that will appear once we schedule threads on more than one
processor. This allows us to hold onto threads without necessarily
holding the scheduler lock for the entire duration.
This commit is contained in:
Tom 2020-09-27 08:53:35 -06:00 • committed by Andreas Kling
parent 079486ed7e
commit 838d9fa251
14 changed files with 136 additions and 90 deletions
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28
Kernel/Syscalls/thread.cpp
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@ -102,8 +102,7 @@ void Process::sys$exit_thread(Userspace<void*> exit_value)
int Process::sys$detach_thread(pid_t tid)
{
REQUIRE_PROMISE(thread);
InterruptDisabler disabler;
auto* thread = Thread::from_tid(tid);
auto thread = Thread::from_tid(tid);
if (!thread || thread->pid() != pid())
return -ESRCH;
@ -118,8 +117,7 @@ int Process::sys$join_thread(pid_t tid, Userspace<void**> exit_value)
{
REQUIRE_PROMISE(thread);
InterruptDisabler disabler;
auto* thread = Thread::from_tid(tid);
auto thread = Thread::from_tid(tid);
if (!thread || thread->pid() != pid())
return -ESRCH;
@ -134,20 +132,14 @@ int Process::sys$join_thread(pid_t tid, Userspace<void**> exit_value)
KResult try_join_result(KSuccess);
auto result = current_thread->block<Thread::JoinBlocker>(nullptr, *thread, try_join_result, joinee_exit_value);
if (result == Thread::BlockResult::NotBlocked) {
ASSERT_INTERRUPTS_DISABLED();
if (try_join_result.is_error())
return try_join_result.error();
break;
}
if (result == Thread::BlockResult::InterruptedByDeath) {
ASSERT_INTERRUPTS_DISABLED();
break;
}
if (result == Thread::BlockResult::InterruptedByDeath)
return 0; // we're not going to return back to user mode
}
// NOTE: 'thread' is very possibly deleted at this point. Clear it just to be safe.
thread = nullptr;
if (exit_value && !copy_to_user(exit_value, &joinee_exit_value))
return -EFAULT;
return 0;
@ -164,8 +156,7 @@ int Process::sys$set_thread_name(pid_t tid, Userspace<const char*> user_name, si
if (name.length() > max_thread_name_size)
return -EINVAL;
InterruptDisabler disabler;
auto* thread = Thread::from_tid(tid);
auto thread = Thread::from_tid(tid);
if (!thread || thread->pid() != pid())
return -ESRCH;
@ -179,15 +170,16 @@ int Process::sys$get_thread_name(pid_t tid, Userspace<char*> buffer, size_t buff
if (buffer_size == 0)
return -EINVAL;
InterruptDisabler disabler;
auto* thread = Thread::from_tid(tid);
auto thread = Thread::from_tid(tid);
if (!thread || thread->pid() != pid())
return -ESRCH;
if (thread->name().length() + 1 > (size_t)buffer_size)
// We must make a temporary copy here to avoid a race with sys$set_thread_name
auto thread_name = thread->name();
if (thread_name.length() + 1 > (size_t)buffer_size)
return -ENAMETOOLONG;
if (!copy_to_user(buffer, thread->name().characters(), thread->name().length() + 1))
if (!copy_to_user(buffer, thread_name.characters(), thread_name.length() + 1))
return -EFAULT;
return 0;
}