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Kernel: Remove ProcessInspectionHandle and make Process RefCounted

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By making the Process class RefCounted we don't really need
ProcessInspectionHandle anymore. This also fixes some race
conditions where a Process may be deleted while still being
used by ProcFS.

Also make sure to acquire the Process' lock when accessing
regions.

Last but not least, there's no reason why a thread can't be
scheduled while being inspected, though in practice it won't
happen anyway because the scheduler lock is held at the same
time.
This commit is contained in:
Tom 2020-08-01 20:04:56 -06:00 • committed by Andreas Kling
parent 5bbf6ed46b
commit 538b985487
13 changed files with 191 additions and 273 deletions
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77
Kernel/Process.h
View file

@ -31,6 +31,7 @@
#include <AK/HashMap.h>
#include <AK/InlineLinkedList.h>
#include <AK/NonnullOwnPtrVector.h>
#include <AK/NonnullRefPtrVector.h>
#include <AK/String.h>
#include <AK/Userspace.h>
#include <AK/WeakPtr.h>
@ -105,7 +106,7 @@ struct UnveiledPath {
unsigned permissions { 0 };
};
class Process : public InlineLinkedListNode<Process> {
class Process : public RefCounted<Process>, public InlineLinkedListNode<Process> {
AK_MAKE_NONCOPYABLE(Process);
AK_MAKE_NONMOVABLE(Process);
@ -119,12 +120,12 @@ public:
return current_thread ? &current_thread->process() : nullptr;
}
static Process* create_kernel_process(Thread*& first_thread, String&& name, void (*entry)(), u32 affinity = THREAD_AFFINITY_DEFAULT);
static Process* create_user_process(Thread*& first_thread, const String& path, uid_t, gid_t, pid_t ppid, int& error, Vector<String>&& arguments = Vector<String>(), Vector<String>&& environment = Vector<String>(), TTY* = nullptr);
static NonnullRefPtr<Process> create_kernel_process(Thread*& first_thread, String&& name, void (*entry)(), u32 affinity = THREAD_AFFINITY_DEFAULT);
static RefPtr<Process> create_user_process(Thread*& first_thread, const String& path, uid_t, gid_t, pid_t ppid, int& error, Vector<String>&& arguments = Vector<String>(), Vector<String>&& environment = Vector<String>(), TTY* = nullptr);
~Process();
static Vector<pid_t> all_pids();
static Vector<Process*> all_processes();
static AK::NonnullRefPtrVector<Process> all_processes();
Thread* create_kernel_thread(void (*entry)(), u32 priority, const String& name, u32 affinity = THREAD_AFFINITY_DEFAULT, bool joinable = true);
@ -136,7 +137,7 @@ public:
Ring3 = 3,
};
KBuffer backtrace(ProcessInspectionHandle&) const;
KBuffer backtrace() const;
bool is_dead() const { return m_dead; }
@ -146,7 +147,7 @@ public:
PageDirectory& page_directory() { return *m_page_directory; }
const PageDirectory& page_directory() const { return *m_page_directory; }
static Process* from_pid(pid_t);
static RefPtr<Process> from_pid(pid_t);
const String& name() const { return m_name; }
pid_t pid() const { return m_pid; }
@ -182,6 +183,8 @@ public:
void die();
void finalize();
ALWAYS_INLINE SpinLock<u32>& get_lock() const { return m_lock; }
int sys$yield();
int sys$sync();
int sys$beep();
@ -343,7 +346,11 @@ public:
void set_tty(TTY*);
size_t region_count() const { return m_regions.size(); }
const NonnullOwnPtrVector<Region>& regions() const { return m_regions; }
const NonnullOwnPtrVector<Region>& regions() const
{
ASSERT(m_lock.is_locked());
return m_regions;
}
void dump_regions();
u32 m_ticks_in_user { 0 };
@ -485,11 +492,6 @@ public:
Region& allocate_split_region(const Region& source_region, const Range&, size_t offset_in_vmobject);
Vector<Region*, 2> split_region_around_range(const Region& source_region, const Range&);
bool is_being_inspected() const
{
return m_inspector_count;
}
void terminate_due_to_signal(u8 signal);
KResult send_signal(u8 signal, Process* sender);
@ -541,15 +543,6 @@ public:
return m_unveiled_paths;
}
void increment_inspector_count(Badge<ProcessInspectionHandle>)
{
++m_inspector_count;
}
void decrement_inspector_count(Badge<ProcessInspectionHandle>)
{
--m_inspector_count;
}
bool wait_for_tracer_at_next_execve() const
{
return m_wait_for_tracer_at_next_execve;
@ -699,50 +692,12 @@ private:
OwnPtr<PerformanceEventBuffer> m_perf_event_buffer;
u32 m_inspector_count { 0 };
// This member is used in the implementation of ptrace's PT_TRACEME flag.
// If it is set to true, the process will stop at the next execve syscall
// and wait for a tracer to attach.
bool m_wait_for_tracer_at_next_execve { false };
};
class ProcessInspectionHandle {
public:
ProcessInspectionHandle(Process& process)
: m_process(process)
{
if (&process != Process::current()) {
InterruptDisabler disabler;
m_process.increment_inspector_count({});
}
}
~ProcessInspectionHandle()
{
if (&m_process != Process::current()) {
InterruptDisabler disabler;
m_process.decrement_inspector_count({});
}
}
Process& process() { return m_process; }
static OwnPtr<ProcessInspectionHandle> from_pid(pid_t pid)
{
InterruptDisabler disabler;
auto* process = Process::from_pid(pid);
if (process)
return make<ProcessInspectionHandle>(*process);
return nullptr;
}
Process* operator->() { return &m_process; }
Process& operator*() { return m_process; }
private:
Process& m_process;
};
extern InlineLinkedList<Process>* g_processes;
extern RecursiveSpinLock g_processes_lock;
@ -833,7 +788,7 @@ inline bool InodeMetadata::may_execute(const Process& process) const
inline int Thread::pid() const
{
return m_process.pid();
return m_process->pid();
}
inline const LogStream& operator<<(const LogStream& stream, const Process& process)
@ -843,7 +798,7 @@ inline const LogStream& operator<<(const LogStream& stream, const Process& proce
inline u32 Thread::effective_priority() const
{
return m_priority + m_process.priority_boost() + m_priority_boost + m_extra_priority;
return m_priority + m_process->priority_boost() + m_priority_boost + m_extra_priority;
}
#define REQUIRE_NO_PROMISES \