Re: [PATCH v2 1/7] rust_binder: Add dynamic debug logging mask

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Fri, Jul 10, 2026 at 02:32:52PM +0000, Jahnavi MN via B4 Relay wrote:
> From: Jahnavi MN <jahnavimn@google.com>
> 
> Implement a dynamic debug logging mask (`debug_mask`) for the
> `rust_binder` module to allow dynamic runtime configuration of log
> levels. This enables parity with the legacy C driver's debug mask.
> 
> Since the Rust `module!` macro in the current kernel build does not yet
> support declaring module parameters directly in Rust, we define the
> `debug_mask` variable in a C companion file to expose it to the kernel
> runtime and import it using FFI with volatile reads.
> 
> To verify the setup, instrument process lifecycle events (open, flush,
> and release) in `process.rs` under the new `BINDER_DEBUG_OPEN_CLOSE`
> logging mask. These entry-point events are chosen for initial validation
> because they represent the start of the Binder lifecycle and occur
> at low frequency, allowing simple runtime verification of the dynamic
> toggle without log noise.
> 
> Signed-off-by: Jahnavi MN <jahnavimn@google.com>
> ---
>  drivers/android/binder/debug.rs            | 80 ++++++++++++++++++++++++++++++
>  drivers/android/binder/process.rs          |  7 ++-
>  drivers/android/binder/rust_binder_main.rs |  2 +
>  drivers/android/binder/rust_binderfs.c     |  3 ++
>  rust/kernel/task.rs                        |  7 +++
>  5 files changed, 98 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/android/binder/debug.rs b/drivers/android/binder/debug.rs
> new file mode 100644
> index 000000000000..da48bce3df54
> --- /dev/null
> +++ b/drivers/android/binder/debug.rs
> @@ -0,0 +1,80 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// Copyright (C) 2026 Google LLC.
> +
> +//! Binder debugging helpers.
> +
> +#![allow(dead_code)]
> +
> +kernel::impl_flags!(
> +    /// Represents multiple debug mask flags.
> +    #[derive(Debug, Clone, Default, Copy, PartialEq, Eq)]
> +    pub struct DebugMasks(u32);
> +
> +    /// Represents a single debug mask category.
> +    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
> +    pub enum DebugMask {
> +        UserError = 1 << 0,
> +        FailedTransaction = 1 << 1,
> +        DeadTransaction = 1 << 2,
> +        OpenClose = 1 << 3,
> +        DeadBinder = 1 << 4,
> +        DeathNotification = 1 << 5,
> +        ReadWrite = 1 << 6,
> +        UserRefs = 1 << 7,
> +        Threads = 1 << 8,
> +        Transaction = 1 << 9,
> +        TransactionComplete = 1 << 10,
> +        FreeBuffer = 1 << 11,
> +        InternalRefs = 1 << 12,
> +        PriorityCap = 1 << 13,
> +        Spinlocks = 1 << 14,

Not an objection, but don't we have the equivalent of the BIT() macro in
rust?  I think that's what this should be using if we do...

thanks,

greg k-h