[PATCH 0/4] rust: replace WARN_ONCE TODOs with pr_warn_once!

[PATCH 0/4] rust: replace WARN_ONCE TODOs with pr_warn_once!

[Adarsh Das]

Replace pr_warn and TODO comments for pr_warn_once with the macro call.

Adarsh Das (4):
  rust: error: use `pr_warn_once!` instead of `pr_warn!`
  rust: module_params: use `pr_warn_once!` instead of `pr_warn!`
  rust: mm: add `pr_warn_once!` for invalid range in
    `zap_page_range_single`
  rust: time: add `pr_warn_once!` for clamped delta in `fsleep`

 rust/kernel/error.rs        | 3 +--
 rust/kernel/mm/virt.rs      | 2 +-
 rust/kernel/module_param.rs | 3 +--
 rust/kernel/time/delay.rs   | 2 +-
 4 files changed, 4 insertions(+), 6 deletions(-)

-- 
2.53.0

[PATCH 1/4] rust: error: use `pr_warn_once!` instead of `pr_warn!`

[Adarsh Das]

Replace the temporary `pr_warn!` call with `pr_warn_once!` and remove the TODO comment.

Signed-off-by: Adarsh Das <adarshdas950@gmail.com>
---
 rust/kernel/error.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/rust/kernel/error.rs b/rust/kernel/error.rs
index 258b12afdcba..562e6daa9151 100644
--- a/rust/kernel/error.rs
+++ b/rust/kernel/error.rs
@@ -124,8 +124,7 @@ pub fn from_errno(errno: crate::ffi::c_int) -> Error {
         if let Some(error) = Self::try_from_errno(errno) {
             error
         } else {
-            // TODO: Make it a `WARN_ONCE` once available.
-            crate::pr_warn!(
+            crate::pr_warn_once!(
                 "attempted to create `Error` with out of range `errno`: {}\n",
                 errno
             );
-- 
2.53.0

[PATCH 2/4] rust: module_params: use `pr_warn_once!` instead of `pr_warn!`

[Adarsh Das]

Replace the temporary `pr_warn!` call with `pr_warn_once!` and remove
the TODO comment.

Signed-off-by: Adarsh Das <adarshdas950@gmail.com>
---
 rust/kernel/module_param.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/rust/kernel/module_param.rs b/rust/kernel/module_param.rs
index 6a8a7a875643..dd6d663a0a3c 100644
--- a/rust/kernel/module_param.rs
+++ b/rust/kernel/module_param.rs
@@ -62,8 +62,7 @@ pub trait ModuleParam: Sized + Copy {
     // NOTE: If we start supporting arguments without values, val _is_ allowed
     // to be null here.
     if val.is_null() {
-        // TODO: Use pr_warn_once available.
-        crate::pr_warn!("Null pointer passed to `module_param::set_param`");
+        crate::pr_warn_once!("Null pointer passed to `module_param::set_param`");
         return EINVAL.to_errno();
     }
 
-- 
2.53.0

[PATCH 3/4] rust: mm: add `pr_warn_once!` for invalid range in `zap_page_range_single`

[Adarsh Das]

Add a warning for the invalid range case and remove the TODO comment.

Signed-off-by: Adarsh Das <adarshdas950@gmail.com>
---
 rust/kernel/mm/virt.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/mm/virt.rs b/rust/kernel/mm/virt.rs
index da21d65ccd20..f608262a4ff8 100644
--- a/rust/kernel/mm/virt.rs
+++ b/rust/kernel/mm/virt.rs
@@ -116,7 +116,7 @@ pub fn end(&self) -> usize {
     pub fn zap_page_range_single(&self, address: usize, size: usize) {
         let (end, did_overflow) = address.overflowing_add(size);
         if did_overflow || address < self.start() || self.end() < end {
-            // TODO: call WARN_ONCE once Rust version of it is added
+            crate::pr_warn_once!("VMA contains invalid range\n");
             return;
         }
 
-- 
2.53.0

[PATCH 4/4] rust: time: add `pr_warn_once!` for clamped delta in `fsleep`

[Adarsh Das]

Add a warning when the delta is clamped to the maximum value and remove the TODO comment.

Signed-off-by: Adarsh Das <adarshdas950@gmail.com>
---
 rust/kernel/time/delay.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/rust/kernel/time/delay.rs b/rust/kernel/time/delay.rs
index b5b1b42797a0..0965fcb6eb80 100644
--- a/rust/kernel/time/delay.rs
+++ b/rust/kernel/time/delay.rs
@@ -35,7 +35,7 @@ pub fn fsleep(delta: Delta) {
     let delta = if (Delta::ZERO..=MAX_DELTA).contains(&delta) {
         delta
     } else {
-        // TODO: Add WARN_ONCE() when it's supported.
+        crate::pr_warn_once!("delta out of range, clamping to maximum\n");
         MAX_DELTA
     };
 
-- 
2.53.0

Re: [PATCH 4/4] rust: time: add `pr_warn_once!` for clamped delta in `fsleep`

[FUJITA Tomonori]

On Thu, 26 Feb 2026 17:38:48 +0530
Adarsh Das <adarshdas950@gmail.com> wrote:

> Add a warning when the delta is clamped to the maximum value and remove the TODO comment.
> 
> Signed-off-by: Adarsh Das <adarshdas950@gmail.com>
> ---
>  rust/kernel/time/delay.rs | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/rust/kernel/time/delay.rs b/rust/kernel/time/delay.rs
> index b5b1b42797a0..0965fcb6eb80 100644
> --- a/rust/kernel/time/delay.rs
> +++ b/rust/kernel/time/delay.rs
> @@ -35,7 +35,7 @@ pub fn fsleep(delta: Delta) {
>      let delta = if (Delta::ZERO..=MAX_DELTA).contains(&delta) {
>          delta
>      } else {
> -        // TODO: Add WARN_ONCE() when it's supported.
> +        crate::pr_warn_once!("delta out of range, clamping to maximum\n");
>          MAX_DELTA
>      };

pr_warn_once() and WARN_ONCE() are different; WARN_ONCE() also dumps a
stack trace, which is more appropriate here, I think.

Re: [PATCH 4/4] rust: time: add `pr_warn_once!` for clamped delta in `fsleep`

[Gary Guo]

On Thu Feb 26, 2026 at 12:59 PM GMT, FUJITA Tomonori wrote:
> On Thu, 26 Feb 2026 17:38:48 +0530
> Adarsh Das <adarshdas950@gmail.com> wrote:
>
>> Add a warning when the delta is clamped to the maximum value and remove the TODO comment.
>> 
>> Signed-off-by: Adarsh Das <adarshdas950@gmail.com>
>> ---
>>  rust/kernel/time/delay.rs | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>> 
>> diff --git a/rust/kernel/time/delay.rs b/rust/kernel/time/delay.rs
>> index b5b1b42797a0..0965fcb6eb80 100644
>> --- a/rust/kernel/time/delay.rs
>> +++ b/rust/kernel/time/delay.rs
>> @@ -35,7 +35,7 @@ pub fn fsleep(delta: Delta) {
>>      let delta = if (Delta::ZERO..=MAX_DELTA).contains(&delta) {
>>          delta
>>      } else {
>> -        // TODO: Add WARN_ONCE() when it's supported.
>> +        crate::pr_warn_once!("delta out of range, clamping to maximum\n");
>>          MAX_DELTA
>>      };
>
> pr_warn_once() and WARN_ONCE() are different; WARN_ONCE() also dumps a
> stack trace, which is more appropriate here, I think.

I think this is also true for patch 1. I think it's fine to add pr_warn_once
before we add `warn_once!()` but the TODO should be kept.

Best,
Gary

Re: [PATCH 4/4] rust: time: add `pr_warn_once!` for clamped delta in `fsleep`

[Greg KH]

On Thu, Feb 26, 2026 at 09:59:23PM +0900, FUJITA Tomonori wrote:
> On Thu, 26 Feb 2026 17:38:48 +0530
> Adarsh Das <adarshdas950@gmail.com> wrote:
> 
> > Add a warning when the delta is clamped to the maximum value and remove the TODO comment.
> > 
> > Signed-off-by: Adarsh Das <adarshdas950@gmail.com>
> > ---
> >  rust/kernel/time/delay.rs | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/rust/kernel/time/delay.rs b/rust/kernel/time/delay.rs
> > index b5b1b42797a0..0965fcb6eb80 100644
> > --- a/rust/kernel/time/delay.rs
> > +++ b/rust/kernel/time/delay.rs
> > @@ -35,7 +35,7 @@ pub fn fsleep(delta: Delta) {
> >      let delta = if (Delta::ZERO..=MAX_DELTA).contains(&delta) {
> >          delta
> >      } else {
> > -        // TODO: Add WARN_ONCE() when it's supported.
> > +        crate::pr_warn_once!("delta out of range, clamping to maximum\n");
> >          MAX_DELTA
> >      };
> 
> pr_warn_once() and WARN_ONCE() are different; WARN_ONCE() also dumps a
> stack trace, which is more appropriate here, I think.

WARN_ONCE() also will panic the machine if panic_on_warn is enabled.  As
it is done in a few billion Linux systems right now :(

So be very careful about that.

thanks,

greg k-h