[PATCH] rust_binder: simplify Result<()> uses

[PATCH] rust_binder: simplify Result<()> uses

[Nicolás Antinori]

`kernel::error::Result<T = (), E = Error>` is a type alias for
`core::result::Result<T, E>` with `()` as the default type argument
for T. Explicitly specifying `Result<()>` is redundant.

This change makes all usages of `Result` consistent across the driver.

Link: https://github.com/Rust-for-Linux/linux/issues/1128
Suggested-by: Miguel Ojeda <ojeda@kernel.org>
Signed-off-by: Nicolás Antinori <nico.antinori.7@gmail.com>
---
 drivers/android/binder/allocation.rs        |  2 +-
 drivers/android/binder/freeze.rs            | 11 ++++-------
 drivers/android/binder/node.rs              | 10 +++-------
 drivers/android/binder/node/wrapper.rs      |  2 +-
 drivers/android/binder/page_range.rs        |  6 +++---
 drivers/android/binder/process.rs           |  4 ++--
 drivers/android/binder/range_alloc/array.rs |  2 +-
 drivers/android/binder/range_alloc/mod.rs   |  2 +-
 drivers/android/binder/range_alloc/tree.rs  |  2 +-
 drivers/android/binder/rust_binder_main.rs  | 12 ++++++------
 drivers/android/binder/thread.rs            |  8 ++++----
 drivers/android/binder/transaction.rs       |  2 +-
 12 files changed, 28 insertions(+), 35 deletions(-)

diff --git a/drivers/android/binder/allocation.rs b/drivers/android/binder/allocation.rs
index 165cb797eb1e..4896ba4b444c 100644
--- a/drivers/android/binder/allocation.rs
+++ b/drivers/android/binder/allocation.rs
@@ -503,7 +503,7 @@ pub(crate) fn read_from(reader: &mut UserSliceReader) -> Result<BinderObject> {
     /// The closure should write the bytes for the object into the provided slice.
     pub(crate) fn read_from_inner<R>(reader: R) -> Result<BinderObject>
     where
-        R: FnOnce(&mut [u8; size_of::<BinderObject>()]) -> Result<()>,
+        R: FnOnce(&mut [u8; size_of::<BinderObject>()]) -> Result,
     {
         let mut obj = MaybeUninit::<BinderObject>::zeroed();

diff --git a/drivers/android/binder/freeze.rs b/drivers/android/binder/freeze.rs
index 66912b4cb527..ea2450f3f16f 100644
--- a/drivers/android/binder/freeze.rs
+++ b/drivers/android/binder/freeze.rs
@@ -155,7 +155,7 @@ fn should_sync_wakeup(&self) -> bool {
     }

     #[inline(never)]
-    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result<()> {
+    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result {
         seq_print!(m, "{}has frozen binder\n", prefix);
         Ok(())
     }
@@ -177,10 +177,7 @@ pub(crate) fn on_process_cleanup(&self, proc: &Process) -> KVVec<Arc<Process>> {
 }

 impl Process {
-    pub(crate) fn request_freeze_notif(
-        self: &Arc<Self>,
-        reader: &mut UserSliceReader,
-    ) -> Result<()> {
+    pub(crate) fn request_freeze_notif(self: &Arc<Self>, reader: &mut UserSliceReader) -> Result {
         let hc = reader.read::<BinderHandleCookie>()?;
         let handle = hc.handle;
         let cookie = FreezeCookie(hc.cookie);
@@ -272,7 +269,7 @@ pub(crate) fn request_freeze_notif(
         Ok(())
     }

-    pub(crate) fn freeze_notif_done(self: &Arc<Self>, reader: &mut UserSliceReader) -> Result<()> {
+    pub(crate) fn freeze_notif_done(self: &Arc<Self>, reader: &mut UserSliceReader) -> Result {
         let cookie = FreezeCookie(reader.read()?);
         let alloc = FreezeMessage::new(GFP_KERNEL)?;
         let mut node_refs_guard = self.node_refs.lock();
@@ -313,7 +310,7 @@ pub(crate) fn freeze_notif_done(self: &Arc<Self>, reader: &mut UserSliceReader)
         Ok(())
     }

-    pub(crate) fn clear_freeze_notif(self: &Arc<Self>, reader: &mut UserSliceReader) -> Result<()> {
+    pub(crate) fn clear_freeze_notif(self: &Arc<Self>, reader: &mut UserSliceReader) -> Result {
         let hc = reader.read::<BinderHandleCookie>()?;
         let handle = hc.handle;
         let cookie = FreezeCookie(hc.cookie);
diff --git a/drivers/android/binder/node.rs b/drivers/android/binder/node.rs
index 0a82af14cda3..b71b423c56bd 100644
--- a/drivers/android/binder/node.rs
+++ b/drivers/android/binder/node.rs
@@ -255,11 +255,7 @@ pub(crate) fn has_oneway_transaction(&self, owner_inner: &mut ProcessInner) -> b
     }

     #[inline(never)]
-    pub(crate) fn full_debug_print(
-        &self,
-        m: &SeqFile,
-        owner_inner: &mut ProcessInner,
-    ) -> Result<()> {
+    pub(crate) fn full_debug_print(&self, m: &SeqFile, owner_inner: &mut ProcessInner) -> Result {
         let inner = self.inner.access_mut(owner_inner);
         seq_print!(
             m,
@@ -745,7 +741,7 @@ fn should_sync_wakeup(&self) -> bool {
     }

     #[inline(never)]
-    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result<()> {
+    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result {
         seq_print!(
             m,
             "{}node work {}: u{:016x} c{:016x}\n",
@@ -1140,7 +1136,7 @@ fn should_sync_wakeup(&self) -> bool {
     }

     #[inline(never)]
-    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result<()> {
+    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result {
         let inner = self.inner.lock();

         let dead_binder = inner.dead && !inner.notification_done;
diff --git a/drivers/android/binder/node/wrapper.rs b/drivers/android/binder/node/wrapper.rs
index 6e4ca01c941a..828a331f5d99 100644
--- a/drivers/android/binder/node/wrapper.rs
+++ b/drivers/android/binder/node/wrapper.rs
@@ -64,7 +64,7 @@ fn should_sync_wakeup(&self) -> bool {
     }

     #[inline(never)]
-    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result<()> {
+    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result {
         seq_print!(
             m,
             "{}node work {}: u{:016x} c{:016x}\n",
diff --git a/drivers/android/binder/page_range.rs b/drivers/android/binder/page_range.rs
index 52ffbf3504e7..047cdf1722cf 100644
--- a/drivers/android/binder/page_range.rs
+++ b/drivers/android/binder/page_range.rs
@@ -66,7 +66,7 @@ impl Shrinker {
     }

     /// Register this shrinker with the kernel.
-    pub(crate) fn register(&'static self, name: &CStr) -> Result<()> {
+    pub(crate) fn register(&'static self, name: &CStr) -> Result {
         // SAFETY: These fields are not yet used, so it's okay to zero them.
         unsafe {
             self.inner.get().write(ptr::null_mut());
@@ -352,7 +352,7 @@ pub(crate) fn register_with_vma(&self, vma: &virt::VmaNew) -> Result<usize> {
     /// Make sure that the given pages are allocated and mapped.
     ///
     /// Must not be called from an atomic context.
-    pub(crate) fn use_range(&self, start: usize, end: usize) -> Result<()> {
+    pub(crate) fn use_range(&self, start: usize, end: usize) -> Result {
         if start >= end {
             return Ok(());
         }
@@ -398,7 +398,7 @@ pub(crate) fn use_range(&self, start: usize, end: usize) -> Result<()> {
     ///
     /// Assumes that `i` is in bounds.
     #[cold]
-    unsafe fn use_page_slow(&self, i: usize) -> Result<()> {
+    unsafe fn use_page_slow(&self, i: usize) -> Result {
         let new_page = Page::alloc_page(GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO)?;

         let mm_mutex = self.mm_lock.lock();
diff --git a/drivers/android/binder/process.rs b/drivers/android/binder/process.rs
index 5372bfbd93b3..124ac221d27a 100644
--- a/drivers/android/binder/process.rs
+++ b/drivers/android/binder/process.rs
@@ -548,7 +548,7 @@ pub(crate) fn pid_in_current_ns(&self) -> kernel::task::Pid {
     }

     #[inline(never)]
-    pub(crate) fn debug_print_stats(&self, m: &SeqFile, ctx: &Context) -> Result<()> {
+    pub(crate) fn debug_print_stats(&self, m: &SeqFile, ctx: &Context) -> Result {
         seq_print!(m, "proc {}\n", self.pid_in_current_ns());
         seq_print!(m, "context {}\n", &*ctx.name);

@@ -596,7 +596,7 @@ pub(crate) fn debug_print_stats(&self, m: &SeqFile, ctx: &Context) -> Result<()>
     }

     #[inline(never)]
-    pub(crate) fn debug_print(&self, m: &SeqFile, ctx: &Context, print_all: bool) -> Result<()> {
+    pub(crate) fn debug_print(&self, m: &SeqFile, ctx: &Context, print_all: bool) -> Result {
         seq_print!(m, "proc {}\n", self.pid_in_current_ns());
         seq_print!(m, "context {}\n", &*ctx.name);

diff --git a/drivers/android/binder/range_alloc/array.rs b/drivers/android/binder/range_alloc/array.rs
index 081d19b09d4b..71bf49f9db0d 100644
--- a/drivers/android/binder/range_alloc/array.rs
+++ b/drivers/android/binder/range_alloc/array.rs
@@ -61,7 +61,7 @@ pub(crate) fn is_full(&self) -> bool {
         self.ranges.len() == self.ranges.capacity()
     }

-    pub(crate) fn debug_print(&self, m: &SeqFile) -> Result<()> {
+    pub(crate) fn debug_print(&self, m: &SeqFile) -> Result {
         for range in &self.ranges {
             seq_print!(
                 m,
diff --git a/drivers/android/binder/range_alloc/mod.rs b/drivers/android/binder/range_alloc/mod.rs
index 1f4734468ff1..bb6e0ec9650e 100644
--- a/drivers/android/binder/range_alloc/mod.rs
+++ b/drivers/android/binder/range_alloc/mod.rs
@@ -141,7 +141,7 @@ pub(crate) fn count_buffers(&self) -> usize {
         }
     }

-    pub(crate) fn debug_print(&self, m: &SeqFile) -> Result<()> {
+    pub(crate) fn debug_print(&self, m: &SeqFile) -> Result {
         match &self.inner {
             Impl::Empty(_size) => Ok(()),
             Impl::Array(array) => array.debug_print(m),
diff --git a/drivers/android/binder/range_alloc/tree.rs b/drivers/android/binder/range_alloc/tree.rs
index 48796fcdb362..058ff7498fa5 100644
--- a/drivers/android/binder/range_alloc/tree.rs
+++ b/drivers/android/binder/range_alloc/tree.rs
@@ -111,7 +111,7 @@ pub(crate) fn count_buffers(&self) -> usize {
             .count()
     }

-    pub(crate) fn debug_print(&self, m: &SeqFile) -> Result<()> {
+    pub(crate) fn debug_print(&self, m: &SeqFile) -> Result {
         for desc in self.tree.values() {
             let state = match &desc.state {
                 Some(state) => &state.0,
diff --git a/drivers/android/binder/rust_binder_main.rs b/drivers/android/binder/rust_binder_main.rs
index 955c4c348f73..aa109663caae 100644
--- a/drivers/android/binder/rust_binder_main.rs
+++ b/drivers/android/binder/rust_binder_main.rs
@@ -158,7 +158,7 @@ fn do_work(
     /// Generally only set to true for non-oneway transactions.
     fn should_sync_wakeup(&self) -> bool;

-    fn debug_print(&self, m: &SeqFile, prefix: &str, transaction_prefix: &str) -> Result<()>;
+    fn debug_print(&self, m: &SeqFile, prefix: &str, transaction_prefix: &str) -> Result;
 }

 // Wrapper around a `DeliverToRead` with linked list links.
@@ -274,7 +274,7 @@ fn should_sync_wakeup(&self) -> bool {
         false
     }

-    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result<()> {
+    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result {
         seq_print!(m, "{}", prefix);
         if self.skip.load(Relaxed) {
             seq_print!(m, "(skipped) ");
@@ -545,7 +545,7 @@ unsafe impl<T> Sync for AssertSync<T> {}
     0
 }

-fn rust_binder_transactions_show_impl(m: &SeqFile) -> Result<()> {
+fn rust_binder_transactions_show_impl(m: &SeqFile) -> Result {
     seq_print!(m, "binder transactions:\n");
     let contexts = context::get_all_contexts()?;
     for ctx in contexts {
@@ -558,7 +558,7 @@ fn rust_binder_transactions_show_impl(m: &SeqFile) -> Result<()> {
     Ok(())
 }

-fn rust_binder_stats_show_impl(m: &SeqFile) -> Result<()> {
+fn rust_binder_stats_show_impl(m: &SeqFile) -> Result {
     seq_print!(m, "binder stats:\n");
     stats::GLOBAL_STATS.debug_print("", m);
     let contexts = context::get_all_contexts()?;
@@ -572,7 +572,7 @@ fn rust_binder_stats_show_impl(m: &SeqFile) -> Result<()> {
     Ok(())
 }

-fn rust_binder_state_show_impl(m: &SeqFile) -> Result<()> {
+fn rust_binder_state_show_impl(m: &SeqFile) -> Result {
     seq_print!(m, "binder state:\n");
     let contexts = context::get_all_contexts()?;
     for ctx in contexts {
@@ -585,7 +585,7 @@ fn rust_binder_state_show_impl(m: &SeqFile) -> Result<()> {
     Ok(())
 }

-fn rust_binder_proc_show_impl(m: &SeqFile, pid: Pid) -> Result<()> {
+fn rust_binder_proc_show_impl(m: &SeqFile, pid: Pid) -> Result {
     seq_print!(m, "binder proc state:\n");
     let contexts = context::get_all_contexts()?;
     for ctx in contexts {
diff --git a/drivers/android/binder/thread.rs b/drivers/android/binder/thread.rs
index 18a14aa8a835..3e898be5ac31 100644
--- a/drivers/android/binder/thread.rs
+++ b/drivers/android/binder/thread.rs
@@ -481,7 +481,7 @@ pub(crate) fn new(id: i32, process: Arc<Process>) -> Result<Arc<Self>> {
     }

     #[inline(never)]
-    pub(crate) fn debug_print(self: &Arc<Self>, m: &SeqFile, print_all: bool) -> Result<()> {
+    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() {
@@ -1250,7 +1250,7 @@ fn read_transaction_info(
         cmd: u32,
         reader: &mut UserSliceReader,
         info: &mut TransactionInfo,
-    ) -> Result<()> {
+    ) -> Result {
         let td = match cmd {
             BC_TRANSACTION | BC_REPLY => {
                 reader.read::<BinderTransactionData>()?.with_buffers_size(0)
@@ -1281,7 +1281,7 @@ fn read_transaction_info(
     }

     #[inline(never)]
-    fn transaction(self: &Arc<Self>, cmd: u32, reader: &mut UserSliceReader) -> Result<()> {
+    fn transaction(self: &Arc<Self>, cmd: u32, reader: &mut UserSliceReader) -> Result {
         let mut info = TransactionInfo::zeroed();
         self.read_transaction_info(cmd, reader, &mut info)?;

@@ -1738,7 +1738,7 @@ fn should_sync_wakeup(&self) -> bool {
         false
     }

-    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result<()> {
+    fn debug_print(&self, m: &SeqFile, prefix: &str, _tprefix: &str) -> Result {
         seq_print!(
             m,
             "{}transaction error: {}\n",
diff --git a/drivers/android/binder/transaction.rs b/drivers/android/binder/transaction.rs
index 245f1556b5db..f6a0707bb4b3 100644
--- a/drivers/android/binder/transaction.rs
+++ b/drivers/android/binder/transaction.rs
@@ -576,7 +576,7 @@ fn should_sync_wakeup(&self) -> bool {
         !self.flags.is_oneway()
     }

-    fn debug_print(&self, m: &SeqFile, _prefix: &str, tprefix: &str) -> Result<()> {
+    fn debug_print(&self, m: &SeqFile, _prefix: &str, tprefix: &str) -> Result {
         self.debug_print_inner(m, tprefix);
         Ok(())
     }
--
2.47.3

Re: [PATCH] rust_binder: simplify Result<()> uses

[Alice Ryhl]

On Mon, Aug 31, 2026 at 07:27:10PM -0300, Nicolás Antinori wrote:
> `kernel::error::Result<T = (), E = Error>` is a type alias for
> `core::result::Result<T, E>` with `()` as the default type argument
> for T. Explicitly specifying `Result<()>` is redundant.
> 
> This change makes all usages of `Result` consistent across the driver.
> 
> Link: https://github.com/Rust-for-Linux/linux/issues/1128
> Suggested-by: Miguel Ojeda <ojeda@kernel.org>
> Signed-off-by: Nicolás Antinori <nico.antinori.7@gmail.com>

I don't really think this matters, but shrug.

Acked-by: Alice Ryhl <aliceryhl@google.com>

Re: [PATCH] rust_binder: simplify Result<()> uses

[Miguel Ojeda]

On Tue, Sep 1, 2026 at 9:49 AM Alice Ryhl <aliceryhl@google.com> wrote:
>
> I don't really think this matters, but shrug.

It is the style we have used since 2021, so it is for consistency, and
it preemptively cleans the `useless_default_generic_parameters` lint
Benno requested:

Link: https://github.com/rust-lang/rust-clippy/issues/14848
Link: https://github.com/rust-lang/rust-clippy/pull/16123

Most of the cases are in Binder at the moment, so this one cleans a
good % of them.

I hope that clarifies.

Cheers,
Miguel