linux-kernel - Re: [PATCH v2 3/3] rust_binder: handle PID namespace conversion for freeze operation

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Message-Id: <20260130052244.834450-1-heesu0025.kim@lge.com>
Date: Fri, 30 Jan 2026 14:22:44 +0900
From: heesu0025.kim@....com
To: aliceryhl@...gle.com
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Subject: Re: [PATCH v2 3/3] rust_binder: handle PID namespace conversion for freeze operation

On Thu, Jan 29, 2026 at 10:35:42AM +0000, Alice Ryhl wrote:
> On Thu, Jan 29, 2026 at 05:41:19PM +0900, jongan.kim@....com wrote:
>> From: HeeSu Kim <heesu0025.kim@....com>
>>
>> Port PID namespace conversion logic from C binder to the Rust
>> implementation.
>>
>> Without namespace conversion, freeze operations from non-init namespaces
>> can match wrong processes due to PID collision. This adds proper
>> conversion to ensure freeze operations target the correct process.
>>
>> Signed-off-by: HeeSu Kim <heesu0025.kim@....com>
>
> Overall looks good, thanks!
>
>> +/// Convert a PID from the current namespace to the global (init) namespace.
>> +fn convert_to_init_ns_tgid(pid: u32) -> Result<i32> {
>
> Let's use the typedef task::Pid (of bindings::pid_t) here, so you can
> avoid the `init_ns_pid as _` cast below.
>
>> +    let current = kernel::current!();
>> +    let init_ns = init_pid_ns();
>> +
>> +    if current.active_pid_ns().map(|ns| ns.as_ptr()) == Some(init_ns.as_ptr()) {
>
> I'd like to avoid comparing raw pointers for this. Perhaps we should just provide
> an implementation of `==` for PidNamespace that compares the address?
>
> Alice

Thanks for the review.

I will address both suggestions in the next revision:
- Use task::Pid typedef to avoid the cast
- Implement PartialEq for PidNamespace for direct comparison

Best Regards,
Heesu Kim