/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <AK/Singleton.h>
#include <Kernel/Process.h>
#include <Kernel/SharedBuffer.h>
//#define SHARED_BUFFER_DEBUG
namespace Kernel {
static AK::Singleton<Lockable<HashMap<int, NonnullOwnPtr<SharedBuffer>>>> s_map;
Lockable<HashMap<int, NonnullOwnPtr<SharedBuffer>>>& shared_buffers()
{
return *s_map;
}
void SharedBuffer::sanity_check(const char* what)
{
LOCKER(shared_buffers().lock(), Lock::Mode::Shared);
unsigned found_refs = 0;
for (const auto& ref : m_refs)
found_refs += ref.count;
if (found_refs != m_total_refs) {
dbg() << what << " sanity -- SharedBuffer{" << this << "} id: " << m_shbuf_id << " has total refs " << m_total_refs << " but we found " << found_refs;
for (const auto& ref : m_refs) {
dbg() << " ref from pid " << ref.pid.value() << ": refcnt " << ref.count;
}
ASSERT_NOT_REACHED();
}
}
bool SharedBuffer::is_shared_with(ProcessID peer_pid) const
{
LOCKER(shared_buffers().lock(), Lock::Mode::Shared);
if (m_global)
return true;
for (auto& ref : m_refs) {
if (ref.pid == peer_pid) {
return true;
}
}
return false;
}
void* SharedBuffer::ref_for_process_and_get_address(Process& process)
{
LOCKER(shared_buffers().lock());
ASSERT(is_shared_with(process.pid()));
if (m_global) {
bool found = false;
for (auto& ref : m_refs) {
if (ref.pid == process.pid()) {
found = true;
break;
}
}
if (!found)
m_refs.append(Reference(process.pid()));
}
for (auto& ref : m_refs) {
if (ref.pid == process.pid()) {
if (!ref.region) {
auto* region = process.allocate_region_with_vmobject(VirtualAddress(), size(), m_vmobject, 0, "SharedBuffer", PROT_READ | (m_writable ? PROT_WRITE : 0));
if (!region)
return (void*)-ENOMEM;
ref.region = region;
region->set_shared(true);
}
ref.count++;
m_total_refs++;
sanity_check("ref_for_process_and_get_address");
return ref.region.unsafe_ptr()->vaddr().as_ptr(); // TODO: Region needs to be RefCounted!
}
}
ASSERT_NOT_REACHED();
}
void SharedBuffer::share_with(ProcessID peer_pid)
{
LOCKER(shared_buffers().lock());
if (m_global)
return;
for (auto& ref : m_refs) {
if (ref.pid == peer_pid) {
// don't increment the reference count yet; let them shbuf_get it first.
sanity_check("share_with (old ref)");
return;
}
}
m_refs.append(Reference(peer_pid));
sanity_check("share_with (new ref)");
}
void SharedBuffer::share_all_shared_buffers(Process& from_process, Process& with_process)
{
LOCKER(shared_buffers().lock());
for (auto& shbuf : shared_buffers().resource()) {
auto& shared_buffer = *shbuf.value;
// We need to clone all references (including for global shared buffers),
// and the reference counts as well.
for (auto& ref : shared_buffer.m_refs) {
if (ref.pid == from_process.pid()) {
auto ref_count = ref.count;
shared_buffer.m_refs.append(Reference(with_process.pid(), ref_count));
// NOTE: ref may become invalid after we appended!
shared_buffer.m_total_refs += ref_count;
break;
}
}
}
}
void SharedBuffer::deref_for_process(Process& process)
{
LOCKER(shared_buffers().lock());
for (size_t i = 0; i < m_refs.size(); ++i) {
auto& ref = m_refs[i];
if (ref.pid == process.pid()) {
ASSERT(ref.count > 0);
ref.count--;
ASSERT(m_total_refs > 0);
m_total_refs--;
if (ref.count == 0) {
#ifdef SHARED_BUFFER_DEBUG
dbg() << "Releasing shared buffer reference on " << m_shbuf_id << " of size " << size() << " by PID " << process.pid().value();
#endif
process.deallocate_region(*ref.region.unsafe_ptr()); // TODO: Region needs to be RefCounted!
#ifdef SHARED_BUFFER_DEBUG
dbg() << "Released shared buffer reference on " << m_shbuf_id << " of size " << size() << " by PID " << process.pid().value();
#endif
sanity_check("deref_for_process");
destroy_if_unused();
return;
}
return;
}
}
ASSERT_NOT_REACHED();
}
bool SharedBuffer::disown(ProcessID pid)
{
LOCKER(shared_buffers().lock());
for (size_t i = 0; i < m_refs.size(); ++i) {
auto& ref = m_refs[i];
if (ref.pid == pid) {
#ifdef SHARED_BUFFER_DEBUG
dbg() << "Disowning shared buffer " << m_shbuf_id << " of size " << size() << " by PID " << pid.value();
#endif
ASSERT(m_total_refs >= ref.count);
m_total_refs -= ref.count;
m_refs.unstable_take(i);
#ifdef SHARED_BUFFER_DEBUG
dbg() << "Disowned shared buffer " << m_shbuf_id << " of size " << size() << " by PID " << pid.value();
#endif
destroy_if_unused();
break;
}
}
return m_total_refs == 0;
}
void SharedBuffer::destroy_if_unused()
{
LOCKER(shared_buffers().lock());
sanity_check("destroy_if_unused");
if (m_total_refs == 0) {
#ifdef SHARED_BUFFER_DEBUG
dbg() << "Destroying unused SharedBuffer{" << this << "} id: " << m_shbuf_id;
#endif
auto count_before = shared_buffers().resource().size();
shared_buffers().resource().remove(m_shbuf_id);
ASSERT(count_before != shared_buffers().resource().size());
}
}
void SharedBuffer::seal()
{
LOCKER(shared_buffers().lock());
m_writable = false;
for (auto& ref : m_refs) {
// TODO: Region needs to be RefCounted!
if (auto* region = ref.region.unsafe_ptr()) {
region->set_writable(false);
region->remap();
}
}
}
}