Nouveau - Nov 2025 - [PATCH v2 1/3] rust: helpers: Add list helpers for C linked list operations

On Wed Nov 12, 2025 at 2:13 AM JST, Joel Fernandes
wrote:
> Add Rust helper functions for common C linked list operations
> that are implemented as macros or inline functions and thus not
> directly accessible from Rust.
>
> Signed-off-by: Joel Fernandes <joelagnelf at nvidia.com>
> ---
>  rust/helpers/helpers.c |  1 +
>  rust/helpers/list.c    | 32 ++++++++++++++++++++++++++++++++
>  2 files changed, 33 insertions(+)
>  create mode 100644 rust/helpers/list.c
>
> diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
> index 79c72762ad9c..634fa2386bbb 100644
> --- a/rust/helpers/helpers.c
> +++ b/rust/helpers/helpers.c
> @@ -32,6 +32,7 @@
>  #include "io.c"
>  #include "jump_label.c"
>  #include "kunit.c"
> +#include "list.c"
>  #include "maple_tree.c"
>  #include "mm.c"
>  #include "mutex.c"
> diff --git a/rust/helpers/list.c b/rust/helpers/list.c
> new file mode 100644
> index 000000000000..fea2a18621da
> --- /dev/null
> +++ b/rust/helpers/list.c
> @@ -0,0 +1,32 @@
> +// SPDX-License-Identifier: GPL-2.0
> +
> +/*
> + * Helpers for C Circular doubly linked list implementation.
> + */
> +
> +#include <linux/list.h>
> +
> +bool rust_helper_list_empty(const struct list_head *head)
> +{
> +	return list_empty(head);
> +}
> +
> +void rust_helper_list_del(struct list_head *entry)
> +{
> +	list_del(entry);
> +}
> +
> +void rust_helper_INIT_LIST_HEAD(struct list_head *list)
> +{
> +	INIT_LIST_HEAD(list);
> +}
> +
> +void rust_helper_list_add(struct list_head *new, struct list_head *head)
> +{
> +	list_add(new, head);
> +}
> +
> +void rust_helper_list_add_tail(struct list_head *new, struct list_head
*head)
> +{
> +	list_add_tail(new, head);
> +}
Just noticed, but of these helpers only `INIT_LIST_HEAD` and
`list_add_tail` seem to be used (in doccomments).

> On Nov 25, 2025, at 9:52?AM, Alexandre Courbot <acourbot at
nvidia.com> wrote:
> 
> ?On Wed Nov 12, 2025 at 2:13 AM JST, Joel Fernandes wrote:
>> Add Rust helper functions for common C linked list operations
>> that are implemented as macros or inline functions and thus not
>> directly accessible from Rust.
>> 
>> Signed-off-by: Joel Fernandes <joelagnelf at nvidia.com>
>> ---
>> rust/helpers/helpers.c |  1 +
>> rust/helpers/list.c    | 32 ++++++++++++++++++++++++++++++++
>> 2 files changed, 33 insertions(+)
>> create mode 100644 rust/helpers/list.c
>> 
>> diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c
>> index 79c72762ad9c..634fa2386bbb 100644
>> --- a/rust/helpers/helpers.c
>> +++ b/rust/helpers/helpers.c
>> @@ -32,6 +32,7 @@
>> #include "io.c"
>> #include "jump_label.c"
>> #include "kunit.c"
>> +#include "list.c"
>> #include "maple_tree.c"
>> #include "mm.c"
>> #include "mutex.c"
>> diff --git a/rust/helpers/list.c b/rust/helpers/list.c
>> new file mode 100644
>> index 000000000000..fea2a18621da
>> --- /dev/null
>> +++ b/rust/helpers/list.c
>> @@ -0,0 +1,32 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +
>> +/*
>> + * Helpers for C Circular doubly linked list implementation.
>> + */
>> +
>> +#include <linux/list.h>
>> +
>> +bool rust_helper_list_empty(const struct list_head *head)
>> +{
>> +    return list_empty(head);
>> +}
>> +
>> +void rust_helper_list_del(struct list_head *entry)
>> +{
>> +    list_del(entry);
>> +}
>> +
>> +void rust_helper_INIT_LIST_HEAD(struct list_head *list)
>> +{
>> +    INIT_LIST_HEAD(list);
>> +}
>> +
>> +void rust_helper_list_add(struct list_head *new, struct list_head
*head)
>> +{
>> +    list_add(new, head);
>> +}
>> +
>> +void rust_helper_list_add_tail(struct list_head *new, struct list_head
*head)
>> +{
>> +    list_add_tail(new, head);
>> +}
> 
> Just noticed, but of these helpers only `INIT_LIST_HEAD` and
> `list_add_tail` seem to be used (in doccomments).
Correct, but it makes sense to add the most obvious/common ones (also to make it
clear that using these are supported).

Thanks.