Merge tag 'char-misc-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-miscHEADtorvalds/mastertorvalds/HEADmaster

Pull Char/Misc/IIO/Binder updates from Greg KH:
 "Here is the big set of char/misc/iio and other driver subsystem
  changes for 6.18-rc1.

  Loads of different stuff in here, it was a busy development cycle in
  lots of different subsystems, with over 27k new lines added to the
  tree.

  Included in here are:

   - IIO updates including new drivers, reworking of existing apis, and
     other goodness in the sensor subsystems

   - MEI driver updates and additions

   - NVMEM driver updates

   - slimbus removal for an unused driver and some other minor updates

   - coresight driver updates and additions

   - MHI driver updates

   - comedi driver updates and fixes

   - extcon driver updates

   - interconnect driver additions

   - eeprom driver updates and fixes

   - minor UIO driver updates

   - tiny W1 driver updates

  But the majority of new code is in the rust bindings and additions,
  which includes:

   - misc driver rust binding updates for read/write support, we can now
     write "normal" misc drivers in rust fully, and the sample driver
     shows how this can be done.

   - Initial framework for USB driver rust bindings, which are disabled
     for now in the build, due to limited support, but coming in through
     this tree due to dependencies on other rust binding changes that
     were in here. I'll be enabling these back on in the build in the
     usb.git tree after -rc1 is out so that developers can continue to
     work on these in linux-next over the next development cycle.

   - Android Binder driver implemented in Rust.

     This is the big one, and was driving a huge majority of the rust
     binding work over the past years. Right now there are two binder
     drivers in the kernel, selected only at build time as to which one
     to use as binder wants to be included in the system at boot time.

     The binder C maintainers all agreed on this, as eventually, they
     want the C code to be removed from the tree, but it will take a few
     releases to get there while both are maintained to ensure that the
     rust implementation is fully stable and compliant with the existing
     userspace apis.

  All of these have been in linux-next for a while"

* tag 'char-misc-6.18-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (320 commits)
  rust: usb: keep usb::Device private for now
  rust: usb: don't retain device context for the interface parent
  USB: disable rust bindings from the build for now
  samples: rust: add a USB driver sample
  rust: usb: add basic USB abstractions
  coresight: Add label sysfs node support
  dt-bindings: arm: Add label in the coresight components
  coresight: tnoc: add new AMBA ID to support Trace Noc V2
  coresight: Fix incorrect handling for return value of devm_kzalloc
  coresight: tpda: fix the logic to setup the element size
  coresight: trbe: Return NULL pointer for allocation failures
  coresight: Refactor runtime PM
  coresight: Make clock sequence consistent
  coresight: Refactor driver data allocation
  coresight: Consolidate clock enabling
  coresight: Avoid enable programming clock duplicately
  coresight: Appropriately disable trace bus clocks
  coresight: Appropriately disable programming clocks
  coresight: etm4x: Support atclk
  coresight: catu: Support atclk
  ...

1 files changed, 1596 insertions, 0 deletions

diff --git a/drivers/android/binder/thread.rs b/drivers/android/binder/thread.rs
new file mode 100644
index 000000000000..7e34ccd394f8
--- /dev/null
+++ b/drivers/android/binder/thread.rs
@@ -0,0 +1,1596 @@
+// SPDX-License-Identifier: GPL-2.0
+
+// Copyright (C) 2025 Google LLC.
+
+//! This module defines the `Thread` type, which represents a userspace thread that is using
+//! binder.
+//!
+//! The `Process` object stores all of the threads in an rb tree.
+
+use kernel::{
+    bindings,
+    fs::{File, LocalFile},
+    list::{AtomicTracker, List, ListArc, ListLinks, TryNewListArc},
+    prelude::*,
+    security,
+    seq_file::SeqFile,
+    seq_print,
+    sync::poll::{PollCondVar, PollTable},
+    sync::{Arc, SpinLock},
+    task::Task,
+    types::ARef,
+    uaccess::UserSlice,
+    uapi,
+};
+
+use crate::{
+    allocation::{Allocation, AllocationView, BinderObject, BinderObjectRef, NewAllocation},
+    defs::*,
+    error::BinderResult,
+    process::{GetWorkOrRegister, Process},
+    ptr_align,
+    stats::GLOBAL_STATS,
+    transaction::Transaction,
+    BinderReturnWriter, DArc, DLArc, DTRWrap, DeliverCode, DeliverToRead,
+};
+
+use core::{
+    mem::size_of,
+    sync::atomic::{AtomicU32, Ordering},
+};
+
+/// Stores the layout of the scatter-gather entries. This is used during the `translate_objects`
+/// call and is discarded when it returns.
+struct ScatterGatherState {
+    /// A struct that tracks the amount of unused buffer space.
+    unused_buffer_space: UnusedBufferSpace,
+    /// Scatter-gather entries to copy.
+    sg_entries: KVec<ScatterGatherEntry>,
+    /// Indexes into `sg_entries` corresponding to the last binder_buffer_object that
+    /// was processed and all of its ancestors. The array is in sorted order.
+    ancestors: KVec<usize>,
+}
+
+/// This entry specifies an additional buffer that should be copied using the scatter-gather
+/// mechanism.
+struct ScatterGatherEntry {
+    /// The index in the offset array of the BINDER_TYPE_PTR that this entry originates from.
+    obj_index: usize,
+    /// Offset in target buffer.
+    offset: usize,
+    /// User address in source buffer.
+    sender_uaddr: usize,
+    /// Number of bytes to copy.
+    length: usize,
+    /// The minimum offset of the next fixup in this buffer.
+    fixup_min_offset: usize,
+    /// The offsets within this buffer that contain pointers which should be translated.
+    pointer_fixups: KVec<PointerFixupEntry>,
+}
+
+/// This entry specifies that a fixup should happen at `target_offset` of the
+/// buffer. If `skip` is nonzero, then the fixup is a `binder_fd_array_object`
+/// and is applied later. Otherwise if `skip` is zero, then the size of the
+/// fixup is `sizeof::<u64>()` and `pointer_value` is written to the buffer.
+struct PointerFixupEntry {
+    /// The number of bytes to skip, or zero for a `binder_buffer_object` fixup.
+    skip: usize,
+    /// The translated pointer to write when `skip` is zero.
+    pointer_value: u64,
+    /// The offset at which the value should be written. The offset is relative
+    /// to the original buffer.
+    target_offset: usize,
+}
+
+/// Return type of `apply_and_validate_fixup_in_parent`.
+struct ParentFixupInfo {
+    /// The index of the parent buffer in `sg_entries`.
+    parent_sg_index: usize,
+    /// The number of ancestors of the buffer.
+    ///
+    /// The buffer is considered an ancestor of itself, so this is always at
+    /// least one.
+    num_ancestors: usize,
+    /// New value of `fixup_min_offset` if this fixup is applied.
+    new_min_offset: usize,
+    /// The offset of the fixup in the target buffer.
+    target_offset: usize,
+}
+
+impl ScatterGatherState {
+    /// Called when a `binder_buffer_object` or `binder_fd_array_object` tries
+    /// to access a region in its parent buffer. These accesses have various
+    /// restrictions, which this method verifies.
+    ///
+    /// The `parent_offset` and `length` arguments describe the offset and
+    /// length of the access in the parent buffer.
+    ///
+    /// # Detailed restrictions
+    ///
+    /// Obviously the fixup must be in-bounds for the parent buffer.
+    ///
+    /// For safety reasons, we only allow fixups inside a buffer to happen
+    /// at increasing offsets; additionally, we only allow fixup on the last
+    /// buffer object that was verified, or one of its parents.
+    ///
+    /// Example of what is allowed:
+    ///
+    /// A
+    ///   B (parent = A, offset = 0)
+    ///   C (parent = A, offset = 16)
+    ///     D (parent = C, offset = 0)
+    ///   E (parent = A, offset = 32) // min_offset is 16 (C.parent_offset)
+    ///
+    /// Examples of what is not allowed:
+    ///
+    /// Decreasing offsets within the same parent:
+    /// A
+    ///   C (parent = A, offset = 16)
+    ///   B (parent = A, offset = 0) // decreasing offset within A
+    ///
+    /// Arcerring to a parent that wasn't the last object or any of its parents:
+    /// A
+    ///   B (parent = A, offset = 0)
+    ///   C (parent = A, offset = 0)
+    ///   C (parent = A, offset = 16)
+    ///     D (parent = B, offset = 0) // B is not A or any of A's parents
+    fn validate_parent_fixup(
+        &self,
+        parent: usize,
+        parent_offset: usize,
+        length: usize,
+    ) -> Result<ParentFixupInfo> {
+        // Using `position` would also be correct, but `rposition` avoids
+        // quadratic running times.
+        let ancestors_i = self
+            .ancestors
+            .iter()
+            .copied()
+            .rposition(|sg_idx| self.sg_entries[sg_idx].obj_index == parent)
+            .ok_or(EINVAL)?;
+        let sg_idx = self.ancestors[ancestors_i];
+        let sg_entry = match self.sg_entries.get(sg_idx) {
+            Some(sg_entry) => sg_entry,
+            None => {
+                pr_err!(
+                    "self.ancestors[{}] is {}, but self.sg_entries.len() is {}",
+                    ancestors_i,
+                    sg_idx,
+                    self.sg_entries.len()
+                );
+                return Err(EINVAL);
+            }
+        };
+        if sg_entry.fixup_min_offset > parent_offset {
+            pr_warn!(
+                "validate_parent_fixup: fixup_min_offset={}, parent_offset={}",
+                sg_entry.fixup_min_offset,
+                parent_offset
+            );
+            return Err(EINVAL);
+        }
+        let new_min_offset = parent_offset.checked_add(length).ok_or(EINVAL)?;
+        if new_min_offset > sg_entry.length {
+            pr_warn!(
+                "validate_parent_fixup: new_min_offset={}, sg_entry.length={}",
+                new_min_offset,
+                sg_entry.length
+            );
+            return Err(EINVAL);
+        }
+        let target_offset = sg_entry.offset.checked_add(parent_offset).ok_or(EINVAL)?;
+        // The `ancestors_i + 1` operation can't overflow since the output of the addition is at
+        // most `self.ancestors.len()`, which also fits in a usize.
+        Ok(ParentFixupInfo {
+            parent_sg_index: sg_idx,
+            num_ancestors: ancestors_i + 1,
+            new_min_offset,
+            target_offset,
+        })
+    }
+}
+
+/// Keeps track of how much unused buffer space is left. The initial amount is the number of bytes
+/// requested by the user using the `buffers_size` field of `binder_transaction_data_sg`. Each time
+/// we translate an object of type `BINDER_TYPE_PTR`, some of the unused buffer space is consumed.
+struct UnusedBufferSpace {
+    /// The start of the remaining space.
+    offset: usize,
+    /// The end of the remaining space.
+    limit: usize,
+}
+impl UnusedBufferSpace {
+    /// Claim the next `size` bytes from the unused buffer space. The offset for the claimed chunk
+    /// into the buffer is returned.
+    fn claim_next(&mut self, size: usize) -> Result<usize> {
+        // We require every chunk to be aligned.
+        let size = ptr_align(size).ok_or(EINVAL)?;
+        let new_offset = self.offset.checked_add(size).ok_or(EINVAL)?;
+
+        if new_offset <= self.limit {
+            let offset = self.offset;
+            self.offset = new_offset;
+            Ok(offset)
+        } else {
+            Err(EINVAL)
+        }
+    }
+}
+
+pub(crate) enum PushWorkRes {
+    Ok,
+    FailedDead(DLArc<dyn DeliverToRead>),
+}
+
+impl PushWorkRes {
+    fn is_ok(&self) -> bool {
+        match self {
+            PushWorkRes::Ok => true,
+            PushWorkRes::FailedDead(_) => false,
+        }
+    }
+}
+
+/// The fields of `Thread` protected by the spinlock.
+struct InnerThread {
+    /// Determines the looper state of the thread. It is a bit-wise combination of the constants
+    /// prefixed with `LOOPER_`.
+    looper_flags: u32,
+
+    /// Determines whether the looper should return.
+    looper_need_return: bool,
+
+    /// Determines if thread is dead.
+    is_dead: bool,
+
+    /// Work item used to deliver error codes to the thread that started a transaction. Stored here
+    /// so that it can be reused.
+    reply_work: DArc<ThreadError>,
+
+    /// Work item used to deliver error codes to the current thread. Stored here so that it can be
+    /// reused.
+    return_work: DArc<ThreadError>,
+
+    /// Determines whether the work list below should be processed. When set to false, `work_list`
+    /// is treated as if it were empty.
+    process_work_list: bool,
+    /// List of work items to deliver to userspace.
+    work_list: List<DTRWrap<dyn DeliverToRead>>,
+    current_transaction: Option<DArc<Transaction>>,
+
+    /// Extended error information for this thread.
+    extended_error: ExtendedError,
+}
+
+const LOOPER_REGISTERED: u32 = 0x01;
+const LOOPER_ENTERED: u32 = 0x02;
+const LOOPER_EXITED: u32 = 0x04;
+const LOOPER_INVALID: u32 = 0x08;
+const LOOPER_WAITING: u32 = 0x10;
+const LOOPER_WAITING_PROC: u32 = 0x20;
+const LOOPER_POLL: u32 = 0x40;
+
+impl InnerThread {
+    fn new() -> Result<Self> {
+        fn next_err_id() -> u32 {
+            static EE_ID: AtomicU32 = AtomicU32::new(0);
+            EE_ID.fetch_add(1, Ordering::Relaxed)
+        }
+
+        Ok(Self {
+            looper_flags: 0,
+            looper_need_return: false,
+            is_dead: false,
+            process_work_list: false,
+            reply_work: ThreadError::try_new()?,
+            return_work: ThreadError::try_new()?,
+            work_list: List::new(),
+            current_transaction: None,
+            extended_error: ExtendedError::new(next_err_id(), BR_OK, 0),
+        })
+    }
+
+    fn pop_work(&mut self) -> Option<DLArc<dyn DeliverToRead>> {
+        if !self.process_work_list {
+            return None;
+        }
+
+        let ret = self.work_list.pop_front();
+        self.process_work_list = !self.work_list.is_empty();
+        ret
+    }
+
+    fn push_work(&mut self, work: DLArc<dyn DeliverToRead>) -> PushWorkRes {
+        if self.is_dead {
+            PushWorkRes::FailedDead(work)
+        } else {
+            self.work_list.push_back(work);
+            self.process_work_list = true;
+            PushWorkRes::Ok
+        }
+    }
+
+    fn push_reply_work(&mut self, code: u32) {
+        if let Ok(work) = ListArc::try_from_arc(self.reply_work.clone()) {
+            work.set_error_code(code);
+            self.push_work(work);
+        } else {
+            pr_warn!("Thread reply work is already in use.");
+        }
+    }
+
+    fn push_return_work(&mut self, reply: u32) {
+        if let Ok(work) = ListArc::try_from_arc(self.return_work.clone()) {
+            work.set_error_code(reply);
+            self.push_work(work);
+        } else {
+            pr_warn!("Thread return work is already in use.");
+        }
+    }
+
+    /// Used to push work items that do not need to be processed immediately and can wait until the
+    /// thread gets another work item.
+    fn push_work_deferred(&mut self, work: DLArc<dyn DeliverToRead>) {
+        self.work_list.push_back(work);
+    }
+
+    /// Fetches the transaction this thread can reply to. If the thread has a pending transaction
+    /// (that it could respond to) but it has also issued a transaction, it must first wait for the
+    /// previously-issued transaction to complete.
+    ///
+    /// The `thread` parameter should be the thread containing this `ThreadInner`.
+    fn pop_transaction_to_reply(&mut self, thread: &Thread) -> Result<DArc<Transaction>> {
+        let transaction = self.current_transaction.take().ok_or(EINVAL)?;
+        if core::ptr::eq(thread, transaction.from.as_ref()) {
+            self.current_transaction = Some(transaction);
+            return Err(EINVAL);
+        }
+        // Find a new current transaction for this thread.
+        self.current_transaction = transaction.find_from(thread).cloned();
+        Ok(transaction)
+    }
+
+    fn pop_transaction_replied(&mut self, transaction: &DArc<Transaction>) -> bool {
+        match self.current_transaction.take() {
+            None => false,
+            Some(old) => {
+                if !Arc::ptr_eq(transaction, &old) {
+                    self.current_transaction = Some(old);
+                    return false;
+                }
+                self.current_transaction = old.clone_next();
+                true
+            }
+        }
+    }
+
+    fn looper_enter(&mut self) {
+        self.looper_flags |= LOOPER_ENTERED;
+        if self.looper_flags & LOOPER_REGISTERED != 0 {
+            self.looper_flags |= LOOPER_INVALID;
+        }
+    }
+
+    fn looper_register(&mut self, valid: bool) {
+        self.looper_flags |= LOOPER_REGISTERED;
+        if !valid || self.looper_flags & LOOPER_ENTERED != 0 {
+            self.looper_flags |= LOOPER_INVALID;
+        }
+    }
+
+    fn looper_exit(&mut self) {
+        self.looper_flags |= LOOPER_EXITED;
+    }
+
+    /// Determines whether the thread is part of a pool, i.e., if it is a looper.
+    fn is_looper(&self) -> bool {
+        self.looper_flags & (LOOPER_ENTERED | LOOPER_REGISTERED) != 0
+    }
+
+    /// Determines whether the thread should attempt to fetch work items from the process queue.
+    /// This is generally case when the thread is registered as a looper and not part of a
+    /// transaction stack. But if there is local work, we want to return to userspace before we
+    /// deliver any remote work.
+    fn should_use_process_work_queue(&self) -> bool {
+        self.current_transaction.is_none() && !self.process_work_list && self.is_looper()
+    }
+
+    fn poll(&mut self) -> u32 {
+        self.looper_flags |= LOOPER_POLL;
+        if self.process_work_list || self.looper_need_return {
+            bindings::POLLIN
+        } else {
+            0
+        }
+    }
+}
+
+/// This represents a thread that's used with binder.
+#[pin_data]
+pub(crate) struct Thread {
+    pub(crate) id: i32,
+    pub(crate) process: Arc<Process>,
+    pub(crate) task: ARef<Task>,
+    #[pin]
+    inner: SpinLock<InnerThread>,
+    #[pin]
+    work_condvar: PollCondVar,
+    /// Used to insert this thread into the process' `ready_threads` list.
+    ///
+    /// INVARIANT: May never be used for any other list than the `self.process.ready_threads`.
+    #[pin]
+    links: ListLinks,
+    #[pin]
+    links_track: AtomicTracker,
+}
+
+kernel::list::impl_list_arc_safe! {
+    impl ListArcSafe<0> for Thread {
+        tracked_by links_track: AtomicTracker;
+    }
+}
+kernel::list::impl_list_item! {
+    impl ListItem<0> for Thread {
+        using ListLinks { self.links };
+    }
+}
+
+impl Thread {
+    pub(crate) fn new(id: i32, process: Arc<Process>) -> Result<Arc<Self>> {
+        let inner = InnerThread::new()?;
+
+        Arc::pin_init(
+            try_pin_init!(Thread {
+                id,
+                process,
+                task: ARef::from(&**kernel::current!()),
+                inner <- kernel::new_spinlock!(inner, "Thread::inner"),
+                work_condvar <- kernel::new_poll_condvar!("Thread::work_condvar"),
+                links <- ListLinks::new(),
+                links_track <- AtomicTracker::new(),
+            }),
+            GFP_KERNEL,
+        )
+    }
+
+    #[inline(never)]
+    pub(crate) fn debug_print(self: &Arc<Self>, m: &SeqFile, print_all: bool) -> Result<()> {
+        let inner = self.inner.lock();
+
+        if print_all || inner.current_transaction.is_some() || !inner.work_list.is_empty() {
+            seq_print!(
+                m,
+                "  thread {}: l {:02x} need_return {}\n",
+                self.id,
+                inner.looper_flags,
+                inner.looper_need_return,
+            );
+        }
+
+        let mut t_opt = inner.current_transaction.as_ref();
+        while let Some(t) = t_opt {
+            if Arc::ptr_eq(&t.from, self) {
+                t.debug_print_inner(m, "    outgoing transaction ");
+                t_opt = t.from_parent.as_ref();
+            } else if Arc::ptr_eq(&t.to, &self.process) {
+                t.debug_print_inner(m, "    incoming transaction ");
+                t_opt = t.find_from(self);
+            } else {
+                t.debug_print_inner(m, "    bad transaction ");
+                t_opt = None;
+            }
+        }
+
+        for work in &inner.work_list {
+            work.debug_print(m, "    ", "    pending transaction ")?;
+        }
+        Ok(())
+    }
+
+    pub(crate) fn get_extended_error(&self, data: UserSlice) -> Result {
+        let mut writer = data.writer();
+        let ee = self.inner.lock().extended_error;
+        writer.write(&ee)?;
+        Ok(())
+    }
+
+    pub(crate) fn set_current_transaction(&self, transaction: DArc<Transaction>) {
+        self.inner.lock().current_transaction = Some(transaction);
+    }
+
+    pub(crate) fn has_current_transaction(&self) -> bool {
+        self.inner.lock().current_transaction.is_some()
+    }
+
+    /// Attempts to fetch a work item from the thread-local queue. The behaviour if the queue is
+    /// empty depends on `wait`: if it is true, the function waits for some work to be queued (or a
+    /// signal); otherwise it returns indicating that none is available.
+    fn get_work_local(self: &Arc<Self>, wait: bool) -> Result<Option<DLArc<dyn DeliverToRead>>> {
+        {
+            let mut inner = self.inner.lock();
+            if inner.looper_need_return {
+                return Ok(inner.pop_work());
+            }
+        }
+
+        // Try once if the caller does not want to wait.
+        if !wait {
+            return self.inner.lock().pop_work().ok_or(EAGAIN).map(Some);
+        }
+
+        // Loop waiting only on the local queue (i.e., not registering with the process queue).
+        let mut inner = self.inner.lock();
+        loop {
+            if let Some(work) = inner.pop_work() {
+                return Ok(Some(work));
+            }
+
+            inner.looper_flags |= LOOPER_WAITING;
+            let signal_pending = self.work_condvar.wait_interruptible_freezable(&mut inner);
+            inner.looper_flags &= !LOOPER_WAITING;
+
+            if signal_pending {
+                return Err(EINTR);
+            }
+            if inner.looper_need_return {
+                return Ok(None);
+            }
+        }
+    }
+
+    /// Attempts to fetch a work item from the thread-local queue, falling back to the process-wide
+    /// queue if none is available locally.
+    ///
+    /// This must only be called when the thread is not participating in a transaction chain. If it
+    /// is, the local version (`get_work_local`) should be used instead.
+    fn get_work(self: &Arc<Self>, wait: bool) -> Result<Option<DLArc<dyn DeliverToRead>>> {
+        // Try to get work from the thread's work queue, using only a local lock.
+        {
+            let mut inner = self.inner.lock();
+            if let Some(work) = inner.pop_work() {
+                return Ok(Some(work));
+            }
+            if inner.looper_need_return {
+                drop(inner);
+                return Ok(self.process.get_work());
+            }
+        }
+
+        // If the caller doesn't want to wait, try to grab work from the process queue.
+        //
+        // We know nothing will have been queued directly to the thread queue because it is not in
+        // a transaction and it is not in the process' ready list.
+        if !wait {
+            return self.process.get_work().ok_or(EAGAIN).map(Some);
+        }
+
+        // Get work from the process queue. If none is available, atomically register as ready.
+        let reg = match self.process.get_work_or_register(self) {
+            GetWorkOrRegister::Work(work) => return Ok(Some(work)),
+            GetWorkOrRegister::Register(reg) => reg,
+        };
+
+        let mut inner = self.inner.lock();
+        loop {
+            if let Some(work) = inner.pop_work() {
+                return Ok(Some(work));
+            }
+
+            inner.looper_flags |= LOOPER_WAITING | LOOPER_WAITING_PROC;
+            let signal_pending = self.work_condvar.wait_interruptible_freezable(&mut inner);
+            inner.looper_flags &= !(LOOPER_WAITING | LOOPER_WAITING_PROC);
+
+            if signal_pending || inner.looper_need_return {
+                // We need to return now. We need to pull the thread off the list of ready threads
+                // (by dropping `reg`), then check the state again after it's off the list to
+                // ensure that something was not queued in the meantime. If something has been
+                // queued, we just return it (instead of the error).
+                drop(inner);
+                drop(reg);
+
+                let res = match self.inner.lock().pop_work() {
+                    Some(work) => Ok(Some(work)),
+                    None if signal_pending => Err(EINTR),
+                    None => Ok(None),
+                };
+                return res;
+            }
+        }
+    }
+
+    /// Push the provided work item to be delivered to user space via this thread.
+    ///
+    /// Returns whether the item was successfully pushed. This can only fail if the thread is dead.
+    pub(crate) fn push_work(&self, work: DLArc<dyn DeliverToRead>) -> PushWorkRes {
+        let sync = work.should_sync_wakeup();
+
+        let res = self.inner.lock().push_work(work);
+
+        if res.is_ok() {
+            if sync {
+                self.work_condvar.notify_sync();
+            } else {
+                self.work_condvar.notify_one();
+            }
+        }
+
+        res
+    }
+
+    /// Attempts to push to given work item to the thread if it's a looper thread (i.e., if it's
+    /// part of a thread pool) and is alive. Otherwise, push the work item to the process instead.
+    pub(crate) fn push_work_if_looper(&self, work: DLArc<dyn DeliverToRead>) -> BinderResult {
+        let mut inner = self.inner.lock();
+        if inner.is_looper() && !inner.is_dead {
+            inner.push_work(work);
+            Ok(())
+        } else {
+            drop(inner);
+            self.process.push_work(work)
+        }
+    }
+
+    pub(crate) fn push_work_deferred(&self, work: DLArc<dyn DeliverToRead>) {
+        self.inner.lock().push_work_deferred(work);
+    }
+
+    pub(crate) fn push_return_work(&self, reply: u32) {
+        self.inner.lock().push_return_work(reply);
+    }
+
+    fn translate_object(
+        &self,
+        obj_index: usize,
+        offset: usize,
+        object: BinderObjectRef<'_>,
+        view: &mut AllocationView<'_>,
+        allow_fds: bool,
+        sg_state: &mut ScatterGatherState,
+    ) -> BinderResult {
+        match object {
+            BinderObjectRef::Binder(obj) => {
+                let strong = obj.hdr.type_ == BINDER_TYPE_BINDER;
+                // SAFETY: `binder` is a `binder_uintptr_t`; any bit pattern is a valid
+                // representation.
+                let ptr = unsafe { obj.__bindgen_anon_1.binder } as _;
+                let cookie = obj.cookie as _;
+                let flags = obj.flags as _;
+                let node = self
+                    .process
+                    .as_arc_borrow()
+                    .get_node(ptr, cookie, flags, strong, self)?;
+                security::binder_transfer_binder(&self.process.cred, &view.alloc.process.cred)?;
+                view.transfer_binder_object(offset, obj, strong, node)?;
+            }
+            BinderObjectRef::Handle(obj) => {
+                let strong = obj.hdr.type_ == BINDER_TYPE_HANDLE;
+                // SAFETY: `handle` is a `u32`; any bit pattern is a valid representation.
+                let handle = unsafe { obj.__bindgen_anon_1.handle } as _;
+                let node = self.process.get_node_from_handle(handle, strong)?;
+                security::binder_transfer_binder(&self.process.cred, &view.alloc.process.cred)?;
+                view.transfer_binder_object(offset, obj, strong, node)?;
+            }
+            BinderObjectRef::Fd(obj) => {
+                if !allow_fds {
+                    return Err(EPERM.into());
+                }
+
+                // SAFETY: `fd` is a `u32`; any bit pattern is a valid representation.
+                let fd = unsafe { obj.__bindgen_anon_1.fd };
+                let file = LocalFile::fget(fd)?;
+                // SAFETY: The binder driver never calls `fdget_pos` and this code runs from an
+                // ioctl, so there are no active calls to `fdget_pos` on this thread.
+                let file = unsafe { LocalFile::assume_no_fdget_pos(file) };
+                security::binder_transfer_file(
+                    &self.process.cred,
+                    &view.alloc.process.cred,
+                    &file,
+                )?;
+
+                let mut obj_write = BinderFdObject::default();
+                obj_write.hdr.type_ = BINDER_TYPE_FD;
+                // This will be overwritten with the actual fd when the transaction is received.
+                obj_write.__bindgen_anon_1.fd = u32::MAX;
+                obj_write.cookie = obj.cookie;
+                view.write::<BinderFdObject>(offset, &obj_write)?;
+
+                const FD_FIELD_OFFSET: usize =
+                    core::mem::offset_of!(uapi::binder_fd_object, __bindgen_anon_1.fd);
+
+                let field_offset = offset + FD_FIELD_OFFSET;
+
+                view.alloc.info_add_fd(file, field_offset, false)?;
+            }
+            BinderObjectRef::Ptr(obj) => {
+                let obj_length = obj.length.try_into().map_err(|_| EINVAL)?;
+                let alloc_offset = match sg_state.unused_buffer_space.claim_next(obj_length) {
+                    Ok(alloc_offset) => alloc_offset,
+                    Err(err) => {
+                        pr_warn!(
+                            "Failed to claim space for a BINDER_TYPE_PTR. (offset: {}, limit: {}, size: {})",
+                            sg_state.unused_buffer_space.offset,
+                            sg_state.unused_buffer_space.limit,
+                            obj_length,
+                        );
+                        return Err(err.into());
+                    }
+                };
+
+                let sg_state_idx = sg_state.sg_entries.len();
+                sg_state.sg_entries.push(
+                    ScatterGatherEntry {
+                        obj_index,
+                        offset: alloc_offset,
+                        sender_uaddr: obj.buffer as _,
+                        length: obj_length,
+                        pointer_fixups: KVec::new(),
+                        fixup_min_offset: 0,
+                    },
+                    GFP_KERNEL,
+                )?;
+
+                let buffer_ptr_in_user_space = (view.alloc.ptr + alloc_offset) as u64;
+
+                if obj.flags & uapi::BINDER_BUFFER_FLAG_HAS_PARENT == 0 {
+                    sg_state.ancestors.clear();
+                    sg_state.ancestors.push(sg_state_idx, GFP_KERNEL)?;
+                } else {
+                    // Another buffer also has a pointer to this buffer, and we need to fixup that
+                    // pointer too.
+
+                    let parent_index = usize::try_from(obj.parent).map_err(|_| EINVAL)?;
+                    let parent_offset = usize::try_from(obj.parent_offset).map_err(|_| EINVAL)?;
+
+                    let info = sg_state.validate_parent_fixup(
+                        parent_index,
+                        parent_offset,
+                        size_of::<u64>(),
+                    )?;
+
+                    sg_state.ancestors.truncate(info.num_ancestors);
+                    sg_state.ancestors.push(sg_state_idx, GFP_KERNEL)?;
+
+                    let parent_entry = match sg_state.sg_entries.get_mut(info.parent_sg_index) {
+                        Some(parent_entry) => parent_entry,
+                        None => {
+                            pr_err!(
+                                "validate_parent_fixup returned index out of bounds for sg.entries"
+                            );
+                            return Err(EINVAL.into());
+                        }
+                    };
+
+                    parent_entry.fixup_min_offset = info.new_min_offset;
+                    parent_entry.pointer_fixups.push(
+                        PointerFixupEntry {
+                            skip: 0,
+                            pointer_value: buffer_ptr_in_user_space,
+                            target_offset: info.target_offset,
+                        },
+                        GFP_KERNEL,
+                    )?;
+                }
+
+                let mut obj_write = BinderBufferObject::default();
+                obj_write.hdr.type_ = BINDER_TYPE_PTR;
+                obj_write.flags = obj.flags;
+                obj_write.buffer = buffer_ptr_in_user_space;
+                obj_write.length = obj.length;
+                obj_write.parent = obj.parent;
+                obj_write.parent_offset = obj.parent_offset;
+                view.write::<BinderBufferObject>(offset, &obj_write)?;
+            }
+            BinderObjectRef::Fda(obj) => {
+                if !allow_fds {
+                    return Err(EPERM.into());
+                }
+                let parent_index = usize::try_from(obj.parent).map_err(|_| EINVAL)?;
+                let parent_offset = usize::try_from(obj.parent_offset).map_err(|_| EINVAL)?;
+                let num_fds = usize::try_from(obj.num_fds).map_err(|_| EINVAL)?;
+                let fds_len = num_fds.checked_mul(size_of::<u32>()).ok_or(EINVAL)?;
+
+                let info = sg_state.validate_parent_fixup(parent_index, parent_offset, fds_len)?;
+                view.alloc.info_add_fd_reserve(num_fds)?;
+
+                sg_state.ancestors.truncate(info.num_ancestors);
+                let parent_entry = match sg_state.sg_entries.get_mut(info.parent_sg_index) {
+                    Some(parent_entry) => parent_entry,
+                    None => {
+                        pr_err!(
+                            "validate_parent_fixup returned index out of bounds for sg.entries"
+                        );
+                        return Err(EINVAL.into());
+                    }
+                };
+
+                parent_entry.fixup_min_offset = info.new_min_offset;
+                parent_entry
+                    .pointer_fixups
+                    .push(
+                        PointerFixupEntry {
+                            skip: fds_len,
+                            pointer_value: 0,
+                            target_offset: info.target_offset,
+                        },
+                        GFP_KERNEL,
+                    )
+                    .map_err(|_| ENOMEM)?;
+
+                let fda_uaddr = parent_entry
+                    .sender_uaddr
+                    .checked_add(parent_offset)
+                    .ok_or(EINVAL)?;
+                let mut fda_bytes = KVec::new();
+                UserSlice::new(UserPtr::from_addr(fda_uaddr as _), fds_len)
+                    .read_all(&mut fda_bytes, GFP_KERNEL)?;
+
+                if fds_len != fda_bytes.len() {
+                    pr_err!("UserSlice::read_all returned wrong length in BINDER_TYPE_FDA");
+                    return Err(EINVAL.into());
+                }
+
+                for i in (0..fds_len).step_by(size_of::<u32>()) {
+                    let fd = {
+                        let mut fd_bytes = [0u8; size_of::<u32>()];
+                        fd_bytes.copy_from_slice(&fda_bytes[i..i + size_of::<u32>()]);
+                        u32::from_ne_bytes(fd_bytes)
+                    };
+
+                    let file = LocalFile::fget(fd)?;
+                    // SAFETY: The binder driver never calls `fdget_pos` and this code runs from an
+                    // ioctl, so there are no active calls to `fdget_pos` on this thread.
+                    let file = unsafe { LocalFile::assume_no_fdget_pos(file) };
+                    security::binder_transfer_file(
+                        &self.process.cred,
+                        &view.alloc.process.cred,
+                        &file,
+                    )?;
+
+                    // The `validate_parent_fixup` call ensuers that this addition will not
+                    // overflow.
+                    view.alloc.info_add_fd(file, info.target_offset + i, true)?;
+                }
+                drop(fda_bytes);
+
+                let mut obj_write = BinderFdArrayObject::default();
+                obj_write.hdr.type_ = BINDER_TYPE_FDA;
+                obj_write.num_fds = obj.num_fds;
+                obj_write.parent = obj.parent;
+                obj_write.parent_offset = obj.parent_offset;
+                view.write::<BinderFdArrayObject>(offset, &obj_write)?;
+            }
+        }
+        Ok(())
+    }
+
+    fn apply_sg(&self, alloc: &mut Allocation, sg_state: &mut ScatterGatherState) -> BinderResult {
+        for sg_entry in &mut sg_state.sg_entries {
+            let mut end_of_previous_fixup = sg_entry.offset;
+            let offset_end = sg_entry.offset.checked_add(sg_entry.length).ok_or(EINVAL)?;
+
+            let mut reader =
+                UserSlice::new(UserPtr::from_addr(sg_entry.sender_uaddr), sg_entry.length).reader();
+            for fixup in &mut sg_entry.pointer_fixups {
+                let fixup_len = if fixup.skip == 0 {
+                    size_of::<u64>()
+                } else {
+                    fixup.skip
+                };
+
+                let target_offset_end = fixup.target_offset.checked_add(fixup_len).ok_or(EINVAL)?;
+                if fixup.target_offset < end_of_previous_fixup || offset_end < target_offset_end {
+                    pr_warn!(
+                        "Fixups oob {} {} {} {}",
+                        fixup.target_offset,
+                        end_of_previous_fixup,
+                        offset_end,
+                        target_offset_end
+                    );
+                    return Err(EINVAL.into());
+                }
+
+                let copy_off = end_of_previous_fixup;
+                let copy_len = fixup.target_offset - end_of_previous_fixup;
+                if let Err(err) = alloc.copy_into(&mut reader, copy_off, copy_len) {
+                    pr_warn!("Failed copying into alloc: {:?}", err);
+                    return Err(err.into());
+                }
+                if fixup.skip == 0 {
+                    let res = alloc.write::<u64>(fixup.target_offset, &fixup.pointer_value);
+                    if let Err(err) = res {
+                        pr_warn!("Failed copying ptr into alloc: {:?}", err);
+                        return Err(err.into());
+                    }
+                }
+                if let Err(err) = reader.skip(fixup_len) {
+                    pr_warn!("Failed skipping {} from reader: {:?}", fixup_len, err);
+                    return Err(err.into());
+                }
+                end_of_previous_fixup = target_offset_end;
+            }
+            let copy_off = end_of_previous_fixup;
+            let copy_len = offset_end - end_of_previous_fixup;
+            if let Err(err) = alloc.copy_into(&mut reader, copy_off, copy_len) {
+                pr_warn!("Failed copying remainder into alloc: {:?}", err);
+                return Err(err.into());
+            }
+        }
+        Ok(())
+    }
+
+    /// This method copies the payload of a transaction into the target process.
+    ///
+    /// The resulting payload will have several different components, which will be stored next to
+    /// each other in the allocation. Furthermore, various objects can be embedded in the payload,
+    /// and those objects have to be translated so that they make sense to the target transaction.
+    pub(crate) fn copy_transaction_data(
+        &self,
+        to_process: Arc<Process>,
+        tr: &BinderTransactionDataSg,
+        debug_id: usize,
+        allow_fds: bool,
+        txn_security_ctx_offset: Option<&mut usize>,
+    ) -> BinderResult<NewAllocation> {
+        let trd = &tr.transaction_data;
+        let is_oneway = trd.flags & TF_ONE_WAY != 0;
+        let mut secctx = if let Some(offset) = txn_security_ctx_offset {
+            let secid = self.process.cred.get_secid();
+            let ctx = match security::SecurityCtx::from_secid(secid) {
+                Ok(ctx) => ctx,
+                Err(err) => {
+                    pr_warn!("Failed to get security ctx for id {}: {:?}", secid, err);
+                    return Err(err.into());
+                }
+            };
+            Some((offset, ctx))
+        } else {
+            None
+        };
+
+        let data_size = trd.data_size.try_into().map_err(|_| EINVAL)?;
+        let aligned_data_size = ptr_align(data_size).ok_or(EINVAL)?;
+        let offsets_size = trd.offsets_size.try_into().map_err(|_| EINVAL)?;
+        let aligned_offsets_size = ptr_align(offsets_size).ok_or(EINVAL)?;
+        let buffers_size = tr.buffers_size.try_into().map_err(|_| EINVAL)?;
+        let aligned_buffers_size = ptr_align(buffers_size).ok_or(EINVAL)?;
+        let aligned_secctx_size = match secctx.as_ref() {
+            Some((_offset, ctx)) => ptr_align(ctx.len()).ok_or(EINVAL)?,
+            None => 0,
+        };
+
+        // This guarantees that at least `sizeof(usize)` bytes will be allocated.
+        let len = usize::max(
+            aligned_data_size
+                .checked_add(aligned_offsets_size)
+                .and_then(|sum| sum.checked_add(aligned_buffers_size))
+                .and_then(|sum| sum.checked_add(aligned_secctx_size))
+                .ok_or(ENOMEM)?,
+            size_of::<usize>(),
+        );
+        let secctx_off = aligned_data_size + aligned_offsets_size + aligned_buffers_size;
+        let mut alloc =
+            match to_process.buffer_alloc(debug_id, len, is_oneway, self.process.task.pid()) {
+                Ok(alloc) => alloc,
+                Err(err) => {
+                    pr_warn!(
+                        "Failed to allocate buffer. len:{}, is_oneway:{}",
+                        len,
+                        is_oneway
+                    );
+                    return Err(err);
+                }
+            };
+
+        // SAFETY: This accesses a union field, but it's okay because the field's type is valid for
+        // all bit-patterns.
+        let trd_data_ptr = unsafe { &trd.data.ptr };
+        let mut buffer_reader =
+            UserSlice::new(UserPtr::from_addr(trd_data_ptr.buffer as _), data_size).reader();
+        let mut end_of_previous_object = 0;
+        let mut sg_state = None;
+
+        // Copy offsets if there are any.
+        if offsets_size > 0 {
+            {
+                let mut reader =
+                    UserSlice::new(UserPtr::from_addr(trd_data_ptr.offsets as _), offsets_size)
+                        .reader();
+                alloc.copy_into(&mut reader, aligned_data_size, offsets_size)?;
+            }
+
+            let offsets_start = aligned_data_size;
+            let offsets_end = aligned_data_size + aligned_offsets_size;
+
+            // This state is used for BINDER_TYPE_PTR objects.
+            let sg_state = sg_state.insert(ScatterGatherState {
+                unused_buffer_space: UnusedBufferSpace {
+                    offset: offsets_end,
+                    limit: len,
+                },
+                sg_entries: KVec::new(),
+                ancestors: KVec::new(),
+            });
+
+            // Traverse the objects specified.
+            let mut view = AllocationView::new(&mut alloc, data_size);
+            for (index, index_offset) in (offsets_start..offsets_end)
+                .step_by(size_of::<usize>())
+                .enumerate()
+            {
+                let offset = view.alloc.read(index_offset)?;
+
+                if offset < end_of_previous_object {
+                    pr_warn!("Got transaction with invalid offset.");
+                    return Err(EINVAL.into());
+                }
+
+                // Copy data between two objects.
+                if end_of_previous_object < offset {
+                    view.copy_into(
+                        &mut buffer_reader,
+                        end_of_previous_object,
+                        offset - end_of_previous_object,
+                    )?;
+                }
+
+                let mut object = BinderObject::read_from(&mut buffer_reader)?;
+
+                match self.translate_object(
+                    index,
+                    offset,
+                    object.as_ref(),
+                    &mut view,
+                    allow_fds,
+                    sg_state,
+                ) {
+                    Ok(()) => end_of_previous_object = offset + object.size(),
+                    Err(err) => {
+                        pr_warn!("Error while translating object.");
+                        return Err(err);
+                    }
+                }
+
+                // Update the indexes containing objects to clean up.
+                let offset_after_object = index_offset + size_of::<usize>();
+                view.alloc
+                    .set_info_offsets(offsets_start..offset_after_object);
+            }
+        }
+
+        // Copy remaining raw data.
+        alloc.copy_into(
+            &mut buffer_reader,
+            end_of_previous_object,
+            data_size - end_of_previous_object,
+        )?;
+
+        if let Some(sg_state) = sg_state.as_mut() {
+            if let Err(err) = self.apply_sg(&mut alloc, sg_state) {
+                pr_warn!("Failure in apply_sg: {:?}", err);
+                return Err(err);
+            }
+        }
+
+        if let Some((off_out, secctx)) = secctx.as_mut() {
+            if let Err(err) = alloc.write(secctx_off, secctx.as_bytes()) {
+                pr_warn!("Failed to write security context: {:?}", err);
+                return Err(err.into());
+            }
+            **off_out = secctx_off;
+        }
+        Ok(alloc)
+    }
+
+    fn unwind_transaction_stack(self: &Arc<Self>) {
+        let mut thread = self.clone();
+        while let Ok(transaction) = {
+            let mut inner = thread.inner.lock();
+            inner.pop_transaction_to_reply(thread.as_ref())
+        } {
+            let reply = Err(BR_DEAD_REPLY);
+            if !transaction.from.deliver_single_reply(reply, &transaction) {
+                break;
+            }
+
+            thread = transaction.from.clone();
+        }
+    }
+
+    pub(crate) fn deliver_reply(
+        &self,
+        reply: Result<DLArc<Transaction>, u32>,
+        transaction: &DArc<Transaction>,
+    ) {
+        if self.deliver_single_reply(reply, transaction) {
+            transaction.from.unwind_transaction_stack();
+        }
+    }
+
+    /// Delivers a reply to the thread that started a transaction. The reply can either be a
+    /// reply-transaction or an error code to be delivered instead.
+    ///
+    /// Returns whether the thread is dead. If it is, the caller is expected to unwind the
+    /// transaction stack by completing transactions for threads that are dead.
+    fn deliver_single_reply(
+        &self,
+        reply: Result<DLArc<Transaction>, u32>,
+        transaction: &DArc<Transaction>,
+    ) -> bool {
+        if let Ok(transaction) = &reply {
+            transaction.set_outstanding(&mut self.process.inner.lock());
+        }
+
+        {
+            let mut inner = self.inner.lock();
+            if !inner.pop_transaction_replied(transaction) {
+                return false;
+            }
+
+            if inner.is_dead {
+                return true;
+            }
+
+            match reply {
+                Ok(work) => {
+                    inner.push_work(work);
+                }
+                Err(code) => inner.push_reply_work(code),
+            }
+        }
+
+        // Notify the thread now that we've released the inner lock.
+        self.work_condvar.notify_sync();
+        false
+    }
+
+    /// Determines if the given transaction is the current transaction for this thread.
+    fn is_current_transaction(&self, transaction: &DArc<Transaction>) -> bool {
+        let inner = self.inner.lock();
+        match &inner.current_transaction {
+            None => false,
+            Some(current) => Arc::ptr_eq(current, transaction),
+        }
+    }
+
+    /// Determines the current top of the transaction stack. It fails if the top is in another
+    /// thread (i.e., this thread belongs to a stack but it has called another thread). The top is
+    /// [`None`] if the thread is not currently participating in a transaction stack.
+    fn top_of_transaction_stack(&self) -> Result<Option<DArc<Transaction>>> {
+        let inner = self.inner.lock();
+        if let Some(cur) = &inner.current_transaction {
+            if core::ptr::eq(self, cur.from.as_ref()) {
+                pr_warn!("got new transaction with bad transaction stack");
+                return Err(EINVAL);
+            }
+            Ok(Some(cur.clone()))
+        } else {
+            Ok(None)
+        }
+    }
+
+    fn transaction<T>(self: &Arc<Self>, tr: &BinderTransactionDataSg, inner: T)
+    where
+        T: FnOnce(&Arc<Self>, &BinderTransactionDataSg) -> BinderResult,
+    {
+        if let Err(err) = inner(self, tr) {
+            if err.should_pr_warn() {
+                let mut ee = self.inner.lock().extended_error;
+                ee.command = err.reply;
+                ee.param = err.as_errno();
+                pr_warn!(
+                    "Transaction failed: {:?} my_pid:{}",
+                    err,
+                    self.process.pid_in_current_ns()
+                );
+            }
+
+            self.push_return_work(err.reply);
+        }
+    }
+
+    fn transaction_inner(self: &Arc<Self>, tr: &BinderTransactionDataSg) -> BinderResult {
+        // SAFETY: Handle's type has no invalid bit patterns.
+        let handle = unsafe { tr.transaction_data.target.handle };
+        let node_ref = self.process.get_transaction_node(handle)?;
+        security::binder_transaction(&self.process.cred, &node_ref.node.owner.cred)?;
+        // TODO: We need to ensure that there isn't a pending transaction in the work queue. How
+        // could this happen?
+        let top = self.top_of_transaction_stack()?;
+        let list_completion = DTRWrap::arc_try_new(DeliverCode::new(BR_TRANSACTION_COMPLETE))?;
+        let completion = list_completion.clone_arc();
+        let transaction = Transaction::new(node_ref, top, self, tr)?;
+
+        // Check that the transaction stack hasn't changed while the lock was released, then update
+        // it with the new transaction.
+        {
+            let mut inner = self.inner.lock();
+            if !transaction.is_stacked_on(&inner.current_transaction) {
+                pr_warn!("Transaction stack changed during transaction!");
+                return Err(EINVAL.into());
+            }
+            inner.current_transaction = Some(transaction.clone_arc());
+            // We push the completion as a deferred work so that we wait for the reply before
+            // returning to userland.
+            inner.push_work_deferred(list_completion);
+        }
+
+        if let Err(e) = transaction.submit() {
+            completion.skip();
+            // Define `transaction` first to drop it after `inner`.
+            let transaction;
+            let mut inner = self.inner.lock();
+            transaction = inner.current_transaction.take().unwrap();
+            inner.current_transaction = transaction.clone_next();
+            Err(e)
+        } else {
+            Ok(())
+        }
+    }
+
+    fn reply_inner(self: &Arc<Self>, tr: &BinderTransactionDataSg) -> BinderResult {
+        let orig = self.inner.lock().pop_transaction_to_reply(self)?;
+        if !orig.from.is_current_transaction(&orig) {
+            return Err(EINVAL.into());
+        }
+
+        // We need to complete the transaction even if we cannot complete building the reply.
+        let out = (|| -> BinderResult<_> {
+            let completion = DTRWrap::arc_try_new(DeliverCode::new(BR_TRANSACTION_COMPLETE))?;
+            let process = orig.from.process.clone();
+            let allow_fds = orig.flags & TF_ACCEPT_FDS != 0;
+            let reply = Transaction::new_reply(self, process, tr, allow_fds)?;
+            self.inner.lock().push_work(completion);
+            orig.from.deliver_reply(Ok(reply), &orig);
+            Ok(())
+        })()
+        .map_err(|mut err| {
+            // At this point we only return `BR_TRANSACTION_COMPLETE` to the caller, and we must let
+            // the sender know that the transaction has completed (with an error in this case).
+            pr_warn!(
+                "Failure {:?} during reply - delivering BR_FAILED_REPLY to sender.",
+                err
+            );
+            let reply = Err(BR_FAILED_REPLY);
+            orig.from.deliver_reply(reply, &orig);
+            err.reply = BR_TRANSACTION_COMPLETE;
+            err
+        });
+
+        out
+    }
+
+    fn oneway_transaction_inner(self: &Arc<Self>, tr: &BinderTransactionDataSg) -> BinderResult {
+        // SAFETY: The `handle` field is valid for all possible byte values, so reading from the
+        // union is okay.
+        let handle = unsafe { tr.transaction_data.target.handle };
+        let node_ref = self.process.get_transaction_node(handle)?;
+        security::binder_transaction(&self.process.cred, &node_ref.node.owner.cred)?;
+        let transaction = Transaction::new(node_ref, None, self, tr)?;
+        let code = if self.process.is_oneway_spam_detection_enabled()
+            && transaction.oneway_spam_detected
+        {
+            BR_ONEWAY_SPAM_SUSPECT
+        } else {
+            BR_TRANSACTION_COMPLETE
+        };
+        let list_completion = DTRWrap::arc_try_new(DeliverCode::new(code))?;
+        let completion = list_completion.clone_arc();
+        self.inner.lock().push_work(list_completion);
+        match transaction.submit() {
+            Ok(()) => Ok(()),
+            Err(err) => {
+                completion.skip();
+                Err(err)
+            }
+        }
+    }
+
+    fn write(self: &Arc<Self>, req: &mut BinderWriteRead) -> Result {
+        let write_start = req.write_buffer.wrapping_add(req.write_consumed);
+        let write_len = req.write_size.saturating_sub(req.write_consumed);
+        let mut reader =
+            UserSlice::new(UserPtr::from_addr(write_start as _), write_len as _).reader();
+
+        while reader.len() >= size_of::<u32>() && self.inner.lock().return_work.is_unused() {
+            let before = reader.len();
+            let cmd = reader.read::<u32>()?;
+            GLOBAL_STATS.inc_bc(cmd);
+            self.process.stats.inc_bc(cmd);
+            match cmd {
+                BC_TRANSACTION => {
+                    let tr = reader.read::<BinderTransactionData>()?.with_buffers_size(0);
+                    if tr.transaction_data.flags & TF_ONE_WAY != 0 {
+                        self.transaction(&tr, Self::oneway_transaction_inner);
+                    } else {
+                        self.transaction(&tr, Self::transaction_inner);
+                    }
+                }
+                BC_TRANSACTION_SG => {
+                    let tr = reader.read::<BinderTransactionDataSg>()?;
+                    if tr.transaction_data.flags & TF_ONE_WAY != 0 {
+                        self.transaction(&tr, Self::oneway_transaction_inner);
+                    } else {
+                        self.transaction(&tr, Self::transaction_inner);
+                    }
+                }
+                BC_REPLY => {
+                    let tr = reader.read::<BinderTransactionData>()?.with_buffers_size(0);
+                    self.transaction(&tr, Self::reply_inner)
+                }
+                BC_REPLY_SG => {
+                    let tr = reader.read::<BinderTransactionDataSg>()?;
+                    self.transaction(&tr, Self::reply_inner)
+                }
+                BC_FREE_BUFFER => {
+                    let buffer = self.process.buffer_get(reader.read()?);
+                    if let Some(buffer) = &buffer {
+                        if buffer.looper_need_return_on_free() {
+                            self.inner.lock().looper_need_return = true;
+                        }
+                    }
+                    drop(buffer);
+                }
+                BC_INCREFS => {
+                    self.process
+                        .as_arc_borrow()
+                        .update_ref(reader.read()?, true, false)?
+                }
+                BC_ACQUIRE => {
+                    self.process
+                        .as_arc_borrow()
+                        .update_ref(reader.read()?, true, true)?
+                }
+                BC_RELEASE => {
+                    self.process
+                        .as_arc_borrow()
+                        .update_ref(reader.read()?, false, true)?
+                }
+                BC_DECREFS => {
+                    self.process
+                        .as_arc_borrow()
+                        .update_ref(reader.read()?, false, false)?
+                }
+                BC_INCREFS_DONE => self.process.inc_ref_done(&mut reader, false)?,
+                BC_ACQUIRE_DONE => self.process.inc_ref_done(&mut reader, true)?,
+                BC_REQUEST_DEATH_NOTIFICATION => self.process.request_death(&mut reader, self)?,
+                BC_CLEAR_DEATH_NOTIFICATION => self.process.clear_death(&mut reader, self)?,
+                BC_DEAD_BINDER_DONE => self.process.dead_binder_done(reader.read()?, self),
+                BC_REGISTER_LOOPER => {
+                    let valid = self.process.register_thread();
+                    self.inner.lock().looper_register(valid);
+                }
+                BC_ENTER_LOOPER => self.inner.lock().looper_enter(),
+                BC_EXIT_LOOPER => self.inner.lock().looper_exit(),
+                BC_REQUEST_FREEZE_NOTIFICATION => self.process.request_freeze_notif(&mut reader)?,
+                BC_CLEAR_FREEZE_NOTIFICATION => self.process.clear_freeze_notif(&mut reader)?,
+                BC_FREEZE_NOTIFICATION_DONE => self.process.freeze_notif_done(&mut reader)?,
+
+                // Fail if given an unknown error code.
+                // BC_ATTEMPT_ACQUIRE and BC_ACQUIRE_RESULT are no longer supported.
+                _ => return Err(EINVAL),
+            }
+            // Update the number of write bytes consumed.
+            req.write_consumed += (before - reader.len()) as u64;
+        }
+
+        Ok(())
+    }
+
+    fn read(self: &Arc<Self>, req: &mut BinderWriteRead, wait: bool) -> Result {
+        let read_start = req.read_buffer.wrapping_add(req.read_consumed);
+        let read_len = req.read_size.saturating_sub(req.read_consumed);
+        let mut writer = BinderReturnWriter::new(
+            UserSlice::new(UserPtr::from_addr(read_start as _), read_len as _).writer(),
+            self,
+        );
+        let (in_pool, use_proc_queue) = {
+            let inner = self.inner.lock();
+            (inner.is_looper(), inner.should_use_process_work_queue())
+        };
+
+        let getter = if use_proc_queue {
+            Self::get_work
+        } else {
+            Self::get_work_local
+        };
+
+        // Reserve some room at the beginning of the read buffer so that we can send a
+        // BR_SPAWN_LOOPER if we need to.
+        let mut has_noop_placeholder = false;
+        if req.read_consumed == 0 {
+            if let Err(err) = writer.write_code(BR_NOOP) {
+                pr_warn!("Failure when writing BR_NOOP at beginning of buffer.");
+                return Err(err);
+            }
+            has_noop_placeholder = true;
+        }
+
+        // Loop doing work while there is room in the buffer.
+        let initial_len = writer.len();
+        while writer.len() >= size_of::<uapi::binder_transaction_data_secctx>() + 4 {
+            match getter(self, wait && initial_len == writer.len()) {
+                Ok(Some(work)) => match work.into_arc().do_work(self, &mut writer) {
+                    Ok(true) => {}
+                    Ok(false) => break,
+                    Err(err) => {
+                        return Err(err);
+                    }
+                },
+                Ok(None) => {
+                    break;
+                }
+                Err(err) => {
+                    // Propagate the error if we haven't written anything else.
+                    if err != EINTR && err != EAGAIN {
+                        pr_warn!("Failure in work getter: {:?}", err);
+                    }
+                    if initial_len == writer.len() {
+                        return Err(err);
+                    } else {
+                        break;
+                    }
+                }
+            }
+        }
+
+        req.read_consumed += read_len - writer.len() as u64;
+
+        // Write BR_SPAWN_LOOPER if the process needs more threads for its pool.
+        if has_noop_placeholder && in_pool && self.process.needs_thread() {
+            let mut writer =
+                UserSlice::new(UserPtr::from_addr(req.read_buffer as _), req.read_size as _)
+                    .writer();
+            writer.write(&BR_SPAWN_LOOPER)?;
+        }
+        Ok(())
+    }
+
+    pub(crate) fn write_read(self: &Arc<Self>, data: UserSlice, wait: bool) -> Result {
+        let (mut reader, mut writer) = data.reader_writer();
+        let mut req = reader.read::<BinderWriteRead>()?;
+
+        // Go through the write buffer.
+        let mut ret = Ok(());
+        if req.write_size > 0 {
+            ret = self.write(&mut req);
+            if let Err(err) = ret {
+                pr_warn!(
+                    "Write failure {:?} in pid:{}",
+                    err,
+                    self.process.pid_in_current_ns()
+                );
+                req.read_consumed = 0;
+                writer.write(&req)?;
+                self.inner.lock().looper_need_return = false;
+                return ret;
+            }
+        }
+
+        // Go through the work queue.
+        if req.read_size > 0 {
+            ret = self.read(&mut req, wait);
+            if ret.is_err() && ret != Err(EINTR) {
+                pr_warn!(
+                    "Read failure {:?} in pid:{}",
+                    ret,
+                    self.process.pid_in_current_ns()
+                );
+            }
+        }
+
+        // Write the request back so that the consumed fields are visible to the caller.
+        writer.write(&req)?;
+
+        self.inner.lock().looper_need_return = false;
+
+        ret
+    }
+
+    pub(crate) fn poll(&self, file: &File, table: PollTable<'_>) -> (bool, u32) {
+        table.register_wait(file, &self.work_condvar);
+        let mut inner = self.inner.lock();
+        (inner.should_use_process_work_queue(), inner.poll())
+    }
+
+    /// Make the call to `get_work` or `get_work_local` return immediately, if any.
+    pub(crate) fn exit_looper(&self) {
+        let mut inner = self.inner.lock();
+        let should_notify = inner.looper_flags & LOOPER_WAITING != 0;
+        if should_notify {
+            inner.looper_need_return = true;
+        }
+        drop(inner);
+
+        if should_notify {
+            self.work_condvar.notify_one();
+        }
+    }
+
+    pub(crate) fn notify_if_poll_ready(&self, sync: bool) {
+        // Determine if we need to notify. This requires the lock.
+        let inner = self.inner.lock();
+        let notify = inner.looper_flags & LOOPER_POLL != 0 && inner.should_use_process_work_queue();
+        drop(inner);
+
+        // Now that the lock is no longer held, notify the waiters if we have to.
+        if notify {
+            if sync {
+                self.work_condvar.notify_sync();
+            } else {
+                self.work_condvar.notify_one();
+            }
+        }
+    }
+
+    pub(crate) fn release(self: &Arc<Self>) {
+        self.inner.lock().is_dead = true;
+
+        //self.work_condvar.clear();
+        self.unwind_transaction_stack();
+
+        // Cancel all pending work items.
+        while let Ok(Some(work)) = self.get_work_local(false) {
+            work.into_arc().cancel();
+        }
+    }
+}
+
+#[pin_data]
+struct ThreadError {
+    error_code: AtomicU32,
+    #[pin]
+    links_track: AtomicTracker,
+}
+
+impl ThreadError {
+    fn try_new() -> Result<DArc<Self>> {
+        DTRWrap::arc_pin_init(pin_init!(Self {
+            error_code: AtomicU32::new(BR_OK),
+            links_track <- AtomicTracker::new(),
+        }))
+        .map(ListArc::into_arc)
+    }
+
+    fn set_error_code(&self, code: u32) {
+        self.error_code.store(code, Ordering::Relaxed);
+    }
+
+    fn is_unused(&self) -> bool {
+        self.error_code.load(Ordering::Relaxed) == BR_OK
+    }
+}
+
+impl DeliverToRead for ThreadError {
+    fn do_work(
+        self: DArc<Self>,
+        _thread: &Thread,
+        writer: &mut BinderReturnWriter<'_>,
+    ) -> Result<bool> {
+        let code = self.error_code.load(Ordering::Relaxed);
+        self.error_code.store(BR_OK, Ordering::Relaxed);
+        writer.write_code(code)?;
+        Ok(true)
+    }
+
+    fn cancel(self: DArc<Self>) {}
+
+    fn should_sync_wakeup(&self) -> bool {
+        false
+    }
+
+    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result<()> {
+        seq_print!(
+            m,
+            "{}transaction error: {}\n",
+            prefix,
+            self.error_code.load(Ordering::Relaxed)
+        );
+        Ok(())
+    }
+}
+
+kernel::list::impl_list_arc_safe! {
+    impl ListArcSafe<0> for ThreadError {
+        tracked_by links_track: AtomicTracker;
+    }
+}