diff mbox series

[4/7] rust: init: wrap type checking struct initializers in a closure

Message ID 20230624092330.157338-4-benno.lossin@proton.me
State New
Headers
Series [1/7] rust: init: consolidate init macros |

Commit Message

Benno Lossin June 24, 2023, 9:25 a.m. UTC 
  In the implementation of the init macros there is a `if false` statement
that type checks the initializer to ensure every field is initialized.
Since the next patch has a stack variable to store the struct, the
function might allocate too much memory on debug builds. Putting the
struct into a closure ensures that even in debug builds no stack
overflow error is caused. In release builds this was not a problem since
the code was optimized away due to the `if false`.

Signed-off-by: Benno Lossin <benno.lossin@proton.me>
---
 rust/kernel/init/macros.rs | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

--
2.41.0

Comments

Björn Roy Baron June 24, 2023, 3:03 p.m. UTC | #1 
On Saturday, June 24th, 2023 at 11:25, Benno Lossin <benno.lossin@proton.me> wrote:

> In the implementation of the init macros there is a `if false` statement
> that type checks the initializer to ensure every field is initialized.
> Since the next patch has a stack variable to store the struct, the
> function might allocate too much memory on debug builds. Putting the
> struct into a closure ensures that even in debug builds no stack
> overflow error is caused. In release builds this was not a problem since
> the code was optimized away due to the `if false`.
> 
> Signed-off-by: Benno Lossin <benno.lossin@proton.me>
> ---
>  rust/kernel/init/macros.rs | 18 +++++++++++-------
>  1 file changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs
> index df4281743175..1e0c4aca055a 100644
> --- a/rust/kernel/init/macros.rs
> +++ b/rust/kernel/init/macros.rs
> @@ -1037,14 +1037,18 @@ macro_rules! __init_internal {
>                      // We use unreachable code to ensure that all fields have been mentioned exactly
>                      // once, this struct initializer will still be type-checked and complain with a
>                      // very natural error message if a field is forgotten/mentioned more than once.
> -                    #[allow(unreachable_code, clippy::diverging_sub_expression)]
> +                    #[allow(unreachable_code,
> +                            clippy::diverging_sub_expression,
> +                            clippy::redundant_closure_call)]
>                      if false {
> -                        $crate::__init_internal!(make_initializer:
> -                            @slot(slot),
> -                            @type_name($t),
> -                            @munch_fields($($fields)*,),
> -                            @acc(),
> -                        );
> +                        (|| {
> +                            $crate::__init_internal!(make_initializer:
> +                                @slot(slot),
> +                                @type_name($t),
> +                                @munch_fields($($fields)*,),
> +                                @acc(),
> +                            );
> +                        })();

Is it necessary to call this closure? Typechecking of the closure should happen even without calling it.

>                      }
>                  }
>                  Ok(__InitOk)
> --
> 2.41.0

Cheers,
Björn
Benno Lossin June 24, 2023, 9:05 p.m. UTC | #2 
On 6/24/23 17:03, Björn Roy Baron wrote:
> On Saturday, June 24th, 2023 at 11:25, Benno Lossin <benno.lossin@proton.me> wrote:
> 
>> In the implementation of the init macros there is a `if false` statement
>> that type checks the initializer to ensure every field is initialized.
>> Since the next patch has a stack variable to store the struct, the
>> function might allocate too much memory on debug builds. Putting the
>> struct into a closure ensures that even in debug builds no stack
>> overflow error is caused. In release builds this was not a problem since
>> the code was optimized away due to the `if false`.
>>
>> Signed-off-by: Benno Lossin <benno.lossin@proton.me>
>> ---
>>   rust/kernel/init/macros.rs | 18 +++++++++++-------
>>   1 file changed, 11 insertions(+), 7 deletions(-)
>>
>> diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs
>> index df4281743175..1e0c4aca055a 100644
>> --- a/rust/kernel/init/macros.rs
>> +++ b/rust/kernel/init/macros.rs
>> @@ -1037,14 +1037,18 @@ macro_rules! __init_internal {
>>                       // We use unreachable code to ensure that all fields have been mentioned exactly
>>                       // once, this struct initializer will still be type-checked and complain with a
>>                       // very natural error message if a field is forgotten/mentioned more than once.
>> -                    #[allow(unreachable_code, clippy::diverging_sub_expression)]
>> +                    #[allow(unreachable_code,
>> +                            clippy::diverging_sub_expression,
>> +                            clippy::redundant_closure_call)]
>>                       if false {
>> -                        $crate::__init_internal!(make_initializer:
>> -                            @slot(slot),
>> -                            @type_name($t),
>> -                            @munch_fields($($fields)*,),
>> -                            @acc(),
>> -                        );
>> +                        (|| {
>> +                            $crate::__init_internal!(make_initializer:
>> +                                @slot(slot),
>> +                                @type_name($t),
>> +                                @munch_fields($($fields)*,),
>> +                                @acc(),
>> +                            );
>> +                        })();
> 
> Is it necessary to call this closure? Typechecking of the closure should happen even without calling it.

You are right, I do not need to call it. Will fix.
diff mbox series

Patch

diff --git a/rust/kernel/init/macros.rs b/rust/kernel/init/macros.rs
index df4281743175..1e0c4aca055a 100644
--- a/rust/kernel/init/macros.rs
+++ b/rust/kernel/init/macros.rs
@@ -1037,14 +1037,18 @@  macro_rules! __init_internal {
                     // We use unreachable code to ensure that all fields have been mentioned exactly
                     // once, this struct initializer will still be type-checked and complain with a
                     // very natural error message if a field is forgotten/mentioned more than once.
-                    #[allow(unreachable_code, clippy::diverging_sub_expression)]
+                    #[allow(unreachable_code,
+                            clippy::diverging_sub_expression,
+                            clippy::redundant_closure_call)]
                     if false {
-                        $crate::__init_internal!(make_initializer:
-                            @slot(slot),
-                            @type_name($t),
-                            @munch_fields($($fields)*,),
-                            @acc(),
-                        );
+                        (|| {
+                            $crate::__init_internal!(make_initializer:
+                                @slot(slot),
+                                @type_name($t),
+                                @munch_fields($($fields)*,),
+                                @acc(),
+                            );
+                        })();
                     }
                 }
                 Ok(__InitOk)