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Kernel+Userland: Remove shared buffers (shbufs)

Browse source 
All users of this mechanism have been switched to anonymous files and
passing file descriptors with sendfd()/recvfd().

Shbufs got us where we are today, but it's time we say good-bye to them
and welcome a much more idiomatic replacement. :^)
This commit is contained in:
Andreas Kling 2021-01-17 08:51:41 +01:00
parent 2cd16778b5
commit bf0719092f
28 changed files with 2 additions and 1022 deletions
Download patch file Download diff file Expand all files Collapse all files

2
Kernel/Syscalls/execve.cpp
View file

@ -522,8 +522,6 @@ int Process::do_exec(NonnullRefPtr<FileDescription> main_program_description, Ve
m_region_lookup_cache = {};
disown_all_shared_buffers();
set_dumpable(!executable_is_setid);
for (size_t i = 0; i < m_fds.size(); ++i) {

3
Kernel/Syscalls/fork.cpp
View file

@ -27,7 +27,6 @@
#include <Kernel/FileSystem/Custody.h>
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Process.h>
#include <Kernel/SharedBuffer.h>
#include <Kernel/VM/Region.h>
//#define FORK_DEBUG
@ -80,8 +79,6 @@ pid_t Process::sys$fork(RegisterState& regs)
dbgln("fork: child will begin executing at {:04x}:{:08x} with stack {:04x}:{:08x}, kstack {:04x}:{:08x}", child_tss.cs, child_tss.eip, child_tss.ss, child_tss.esp, child_tss.ss0, child_tss.esp0);
#endif
SharedBuffer::share_all_shared_buffers(*this, *child);
{
ScopedSpinLock lock(m_lock);
for (auto& region : m_regions) {

1
Kernel/Syscalls/process.cpp
View file

@ -26,7 +26,6 @@
#include <AK/Types.h>
#include <Kernel/Process.h>
#include <Kernel/SharedBuffer.h>
namespace Kernel {

137
Kernel/Syscalls/shbuf.cpp
View file

@ -1,137 +0,0 @@
/*
* 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 <Kernel/Process.h>
#include <Kernel/SharedBuffer.h>
//#define SHARED_BUFFER_DEBUG
namespace Kernel {
void Process::disown_all_shared_buffers()
{
LOCKER(shared_buffers().lock());
Vector<SharedBuffer*, 32> buffers_to_disown;
for (auto& it : shared_buffers().resource())
buffers_to_disown.append(it.value.ptr());
for (auto* shared_buffer : buffers_to_disown) {
if (shared_buffer->disown(m_pid)) {
shared_buffers().resource().remove(shared_buffer->id());
delete shared_buffer;
}
}
}
int Process::sys$shbuf_create(int size, void** buffer)
{
REQUIRE_PROMISE(shared_buffer);
if (!size || size < 0)
return -EINVAL;
size = PAGE_ROUND_UP(size);
auto vmobject = AnonymousVMObject::create_with_size(size, AllocationStrategy::Reserve);
if (!vmobject)
return -ENOMEM;
LOCKER(shared_buffers().lock());
static int s_next_shbuf_id;
int shbuf_id = ++s_next_shbuf_id;
auto shared_buffer = make<SharedBuffer>(shbuf_id, vmobject.release_nonnull());
shared_buffer->share_with(m_pid);
void* address = shared_buffer->ref_for_process_and_get_address(*this);
if (!copy_to_user(buffer, &address))
return -EFAULT;
ASSERT((int)shared_buffer->size() >= size);
#ifdef SHARED_BUFFER_DEBUG
klog() << "Created shared buffer " << shbuf_id << " @ " << buffer << " (" << size << " bytes, vmobject is " << shared_buffer->size() << ")";
#endif
shared_buffers().resource().set(shbuf_id, move(shared_buffer));
return shbuf_id;
}
int Process::sys$shbuf_allow_pid(int shbuf_id, pid_t peer_pid)
{
REQUIRE_PROMISE(shared_buffer);
if (!peer_pid || peer_pid < 0 || ProcessID(peer_pid) == m_pid)
return -EINVAL;
LOCKER(shared_buffers().lock());
auto it = shared_buffers().resource().find(shbuf_id);
if (it == shared_buffers().resource().end())
return -EINVAL;
auto& shared_buffer = *(*it).value;
if (!shared_buffer.is_shared_with(m_pid))
return -EPERM;
{
ScopedSpinLock lock(g_processes_lock);
auto peer = Process::from_pid(peer_pid);
if (!peer)
return -ESRCH;
}
shared_buffer.share_with(peer_pid);
return 0;
}
int Process::sys$shbuf_release(int shbuf_id)
{
REQUIRE_PROMISE(shared_buffer);
LOCKER(shared_buffers().lock());
auto it = shared_buffers().resource().find(shbuf_id);
if (it == shared_buffers().resource().end())
return -EINVAL;
auto& shared_buffer = *(*it).value;
if (!shared_buffer.is_shared_with(m_pid))
return -EPERM;
#ifdef SHARED_BUFFER_DEBUG
klog() << "Releasing shared buffer " << shbuf_id << ", buffer count: " << shared_buffers().resource().size();
#endif
shared_buffer.deref_for_process(*this);
return 0;
}
void* Process::sys$shbuf_get(int shbuf_id, Userspace<size_t*> user_size)
{
REQUIRE_PROMISE(shared_buffer);
LOCKER(shared_buffers().lock());
auto it = shared_buffers().resource().find(shbuf_id);
if (it == shared_buffers().resource().end())
return (void*)-EINVAL;
auto& shared_buffer = *(*it).value;
if (!shared_buffer.is_shared_with(m_pid))
return (void*)-EPERM;
#ifdef SHARED_BUFFER_DEBUG
klog() << "Retaining shared buffer " << shbuf_id << ", buffer count: " << shared_buffers().resource().size();
#endif
if (user_size) {
size_t size = shared_buffer.size();
if (!copy_to_user(user_size, &size))
return (void*)-EFAULT;
}
return shared_buffer.ref_for_process_and_get_address(*this);
}
}