Re: [PATCH v10 6/7] rust: ww_mutex: implement LockSet

[kernel test robot <lkp@intel.com>]

Hi Onur,

kernel test robot noticed the following build warnings:

[auto build test WARNING on tip/locking/core]
[also build test WARNING on rust/rust-next linus/master v6.19-rc3 next-20251219]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Onur-zkan/rust-add-C-wrappers-for-ww_mutex-inline-functions/20260103-153912
base:   tip/locking/core
patch link:    https://lore.kernel.org/r/20260103073554.34855-7-work%40onurozkan.dev
patch subject: [PATCH v10 6/7] rust: ww_mutex: implement LockSet
config: x86_64-rhel-9.4-rust (https://download.01.org/0day-ci/archive/20260103/202601031513.bVzSj6aK-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260103/202601031513.bVzSj6aK-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202601031513.bVzSj6aK-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> warning: this let-binding has unit value
   --> rust/kernel/sync/lock/ww_mutex/lock_set.rs:273:17
   |
   273 |                 let _ = lock_set.lock(&mutex1)?;
   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: omit the `let` binding: `lock_set.lock(&mutex1)?;`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_unit_value
   = note: `-W clippy::let-unit-value` implied by `-W clippy::all`
   = help: to override `-W clippy::all` add `#[allow(clippy::let_unit_value)]`
--
>> warning: matching over `()` is more explicit
   --> rust/kernel/sync/lock/ww_mutex/lock_set.rs:273:21
   |
   273 |                 let _ = lock_set.lock(&mutex1)?;
   |                     ^ help: use `()` instead of `_`: `()`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ignored_unit_patterns
   = note: requested on the command line with `-W clippy::ignored-unit-patterns`
--
>> warning: this let-binding has unit value
   --> rust/kernel/sync/lock/ww_mutex/lock_set.rs:274:17
   |
   274 |                 let _ = lock_set.lock(&mutex2)?;
   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: omit the `let` binding: `lock_set.lock(&mutex2)?;`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#let_unit_value
--
>> warning: matching over `()` is more explicit
   --> rust/kernel/sync/lock/ww_mutex/lock_set.rs:274:21
   |
   274 |                 let _ = lock_set.lock(&mutex2)?;
   |                     ^ help: use `()` instead of `_`: `()`
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#ignored_unit_patterns

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