[PATCH v2 00/27] Allow inlining C helpers into Rust when using LTO

[PATCH v2 00/27] Allow inlining C helpers into Rust when using LTO

[Alice Ryhl]

This patch series adds __rust_helper to every single rust helper. The
patches do not depend on each other, so maintainers please go ahead and
pick up any patches relevant to your subsystem! Or provide your Acked-by
so that Miguel can pick them up.

These changes were generated by adding __rust_helper and running
ClangFormat. Unrelated formatting changes were removed manually.

Why is __rust_helper needed?
============================

Currently, C helpers cannot be inlined into Rust even when using LTO
because LLVM detects slightly different options on the codegen units.

* LLVM doesn't want to inline functions compiled with
  `-fno-delete-null-pointer-checks` with code compiled without. The C
  CGUs all have this enabled and Rust CGUs don't. Inlining is okay since
  this is one of the hardening features that does not change the ABI,
  and we shouldn't have null pointer dereferences in these helpers.

* LLVM doesn't want to inline functions with different list of builtins. C
  side has `-fno-builtin-wcslen`; `wcslen` is not a Rust builtin, so
  they should be compatible, but LLVM does not perform inlining due to
  attributes mismatch.

* clang and Rust doesn't have the exact target string. Clang generates
  `+cmov,+cx8,+fxsr` but Rust doesn't enable them (in fact, Rust will
  complain if `-Ctarget-feature=+cmov,+cx8,+fxsr` is used). x86-64
  always enable these features, so they are in fact the same target
  string, but LLVM doesn't understand this and so inlining is inhibited.
  This can be bypassed with `--ignore-tti-inline-compatible`, but this
  is a hidden option.

(This analysis was written by Gary Guo.)

How is this fixed?
==================

To fix this we need to add __always_inline to all helpers when compiling
with LTO. However, it should not be added when running bindgen as
bindgen will ignore functions marked inline. To achieve this, we are
using a #define called __rust_helper that is defined differently
depending on whether bindgen is running or not.

Note that __rust_helper is currently always #defined to nothing.
Changing it to __always_inline will happen separately in another patch
series.

Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
Changes in v2:
- Pick up Reviewed-by: Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>
- Update formatting in mm and slab patches.
- Add new helpers in files uaccess, pwm, and time.
- Drop any patches that have been merged.
- Link to v1: https://lore.kernel.org/r/20251202-define-rust-helper-v1-0-a2e13cbc17a6@google.com

---
Alice Ryhl (27):
      rust: barrier: add __rust_helper to helpers
      rust: blk: add __rust_helper to helpers
      rust: bug: add __rust_helper to helpers
      rust: clk: add __rust_helper to helpers
      rust: completion: add __rust_helper to helpers
      rust: cpu: add __rust_helper to helpers
      rust: cred: add __rust_helper to helpers
      rust: err: add __rust_helper to helpers
      rust: jump_label: add __rust_helper to helpers
      rust: maple_tree: add __rust_helper to helpers
      rust: mm: add __rust_helper to helpers
      rust: of: add __rust_helper to helpers
      rust: processor: add __rust_helper to helpers
      rust: pwm: add __rust_helper to helpers
      rust: rbtree: add __rust_helper to helpers
      rust: rcu: add __rust_helper to helpers
      rust: refcount: add __rust_helper to helpers
      rust: security: add __rust_helper to helpers
      rust: slab: add __rust_helper to helpers
      rust: sync: add __rust_helper to helpers
      rust: task: add __rust_helper to helpers
      rust: time: add __rust_helper to helpers
      rust: uaccess: add __rust_helper to helpers
      rust: usb: add __rust_helper to helpers
      rust: wait: add __rust_helper to helpers
      rust: workqueue: add __rust_helper to helpers
      rust: xarray: add __rust_helper to helpers

 rust/helpers/barrier.c    |  6 +++---
 rust/helpers/blk.c        |  4 ++--
 rust/helpers/bug.c        |  4 ++--
 rust/helpers/build_bug.c  |  2 +-
 rust/helpers/clk.c        | 24 +++++++++++++-----------
 rust/helpers/completion.c |  2 +-
 rust/helpers/cpu.c        |  2 +-
 rust/helpers/cred.c       |  4 ++--
 rust/helpers/err.c        |  6 +++---
 rust/helpers/jump_label.c |  2 +-
 rust/helpers/maple_tree.c |  3 ++-
 rust/helpers/mm.c         | 20 ++++++++++----------
 rust/helpers/mutex.c      | 13 +++++++------
 rust/helpers/of.c         |  2 +-
 rust/helpers/page.c       |  9 +++++----
 rust/helpers/processor.c  |  2 +-
 rust/helpers/pwm.c        |  6 +++---
 rust/helpers/rbtree.c     |  9 +++++----
 rust/helpers/rcu.c        |  4 ++--
 rust/helpers/refcount.c   | 10 +++++-----
 rust/helpers/security.c   | 26 +++++++++++++++-----------
 rust/helpers/signal.c     |  2 +-
 rust/helpers/slab.c       |  4 ++--
 rust/helpers/spinlock.c   | 13 +++++++------
 rust/helpers/sync.c       |  4 ++--
 rust/helpers/task.c       | 24 ++++++++++++------------
 rust/helpers/time.c       | 14 +++++++-------
 rust/helpers/uaccess.c    | 10 ++++++----
 rust/helpers/usb.c        |  3 ++-
 rust/helpers/vmalloc.c    |  2 +-
 rust/helpers/wait.c       |  2 +-
 rust/helpers/workqueue.c  |  8 +++++---
 rust/helpers/xarray.c     | 10 +++++-----
 33 files changed, 136 insertions(+), 120 deletions(-)
---
base-commit: 9ace4753a5202b02191d54e9fdf7f9e3d02b85eb
change-id: 20251202-define-rust-helper-f7b531813007

Best regards,
-- 
Alice Ryhl <aliceryhl@google.com>

[PATCH v2 10/27] rust: maple_tree: add __rust_helper to helpers

[Alice Ryhl]

This is needed to inline these helpers into Rust code.

Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Acked-by: Andrew Ballance <andrewjballance@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Andrew Ballance <andrewjballance@gmail.com>
Cc: maple-tree@lists.infradead.org
Cc: linux-mm@kvack.org
---
 rust/helpers/maple_tree.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/rust/helpers/maple_tree.c b/rust/helpers/maple_tree.c
index 1dd9ac84a13feed53c0ed5eec6805517081d0673..5586486a76e0de60969af1510b4b0428392920e6 100644
--- a/rust/helpers/maple_tree.c
+++ b/rust/helpers/maple_tree.c
@@ -2,7 +2,8 @@
 
 #include <linux/maple_tree.h>
 
-void rust_helper_mt_init_flags(struct maple_tree *mt, unsigned int flags)
+__rust_helper void rust_helper_mt_init_flags(struct maple_tree *mt,
+					     unsigned int flags)
 {
 	mt_init_flags(mt, flags);
 }

-- 
2.52.0.351.gbe84eed79e-goog

[PATCH v2 11/27] rust: mm: add __rust_helper to helpers

[Alice Ryhl]

This is needed to inline these helpers into Rust code.

Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Vitaly Wool <vitaly.wool@konsulko.se>
Cc: linux-mm@kvack.org
---
 rust/helpers/mm.c      | 20 ++++++++++----------
 rust/helpers/page.c    |  9 +++++----
 rust/helpers/vmalloc.c |  2 +-
 3 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/rust/helpers/mm.c b/rust/helpers/mm.c
index 81b510c96fd2692dcb7ab4705f790bd3a41a630e..b5540997bd20d4398e2838956ed70b2fb61c5661 100644
--- a/rust/helpers/mm.c
+++ b/rust/helpers/mm.c
@@ -3,48 +3,48 @@
 #include <linux/mm.h>
 #include <linux/sched/mm.h>
 
-void rust_helper_mmgrab(struct mm_struct *mm)
+__rust_helper void rust_helper_mmgrab(struct mm_struct *mm)
 {
 	mmgrab(mm);
 }
 
-void rust_helper_mmdrop(struct mm_struct *mm)
+__rust_helper void rust_helper_mmdrop(struct mm_struct *mm)
 {
 	mmdrop(mm);
 }
 
-void rust_helper_mmget(struct mm_struct *mm)
+__rust_helper void rust_helper_mmget(struct mm_struct *mm)
 {
 	mmget(mm);
 }
 
-bool rust_helper_mmget_not_zero(struct mm_struct *mm)
+__rust_helper bool rust_helper_mmget_not_zero(struct mm_struct *mm)
 {
 	return mmget_not_zero(mm);
 }
 
-void rust_helper_mmap_read_lock(struct mm_struct *mm)
+__rust_helper void rust_helper_mmap_read_lock(struct mm_struct *mm)
 {
 	mmap_read_lock(mm);
 }
 
-bool rust_helper_mmap_read_trylock(struct mm_struct *mm)
+__rust_helper bool rust_helper_mmap_read_trylock(struct mm_struct *mm)
 {
 	return mmap_read_trylock(mm);
 }
 
-void rust_helper_mmap_read_unlock(struct mm_struct *mm)
+__rust_helper void rust_helper_mmap_read_unlock(struct mm_struct *mm)
 {
 	mmap_read_unlock(mm);
 }
 
-struct vm_area_struct *rust_helper_vma_lookup(struct mm_struct *mm,
-					      unsigned long addr)
+__rust_helper struct vm_area_struct *
+rust_helper_vma_lookup(struct mm_struct *mm, unsigned long addr)
 {
 	return vma_lookup(mm, addr);
 }
 
-void rust_helper_vma_end_read(struct vm_area_struct *vma)
+__rust_helper void rust_helper_vma_end_read(struct vm_area_struct *vma)
 {
 	vma_end_read(vma);
 }
diff --git a/rust/helpers/page.c b/rust/helpers/page.c
index 7144de5a61dbdb3006a668961cd1b09440e74908..f8463fbed2a2670ddfd4c23dc922b46b0913c3a2 100644
--- a/rust/helpers/page.c
+++ b/rust/helpers/page.c
@@ -4,23 +4,24 @@
 #include <linux/highmem.h>
 #include <linux/mm.h>
 
-struct page *rust_helper_alloc_pages(gfp_t gfp_mask, unsigned int order)
+__rust_helper struct page *rust_helper_alloc_pages(gfp_t gfp_mask,
+						   unsigned int order)
 {
 	return alloc_pages(gfp_mask, order);
 }
 
-void *rust_helper_kmap_local_page(struct page *page)
+__rust_helper void *rust_helper_kmap_local_page(struct page *page)
 {
 	return kmap_local_page(page);
 }
 
-void rust_helper_kunmap_local(const void *addr)
+__rust_helper void rust_helper_kunmap_local(const void *addr)
 {
 	kunmap_local(addr);
 }
 
 #ifndef NODE_NOT_IN_PAGE_FLAGS
-int rust_helper_page_to_nid(const struct page *page)
+__rust_helper int rust_helper_page_to_nid(const struct page *page)
 {
 	return page_to_nid(page);
 }
diff --git a/rust/helpers/vmalloc.c b/rust/helpers/vmalloc.c
index 7d7f7336b3d2f5a32e6a2b6cf8407da37775cfd9..326b030487a2b2199283b64b3b427e57cf5fb14a 100644
--- a/rust/helpers/vmalloc.c
+++ b/rust/helpers/vmalloc.c
@@ -2,7 +2,7 @@
 
 #include <linux/vmalloc.h>
 
-void * __must_check __realloc_size(2)
+__rust_helper void *__must_check __realloc_size(2)
 rust_helper_vrealloc_node_align(const void *p, size_t size, unsigned long align,
 				gfp_t flags, int node)
 {

-- 
2.52.0.351.gbe84eed79e-goog

[PATCH v2 27/27] rust: xarray: add __rust_helper to helpers

[Alice Ryhl]

This is needed to inline these helpers into Rust code.

Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
---
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Tamir Duberstein <tamird@gmail.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-mm@kvack.org
---
 rust/helpers/xarray.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/rust/helpers/xarray.c b/rust/helpers/xarray.c
index 60b299f11451d2c4a75e50e25dec4dac13f143f4..08979b3043410ff89d2adc0b2597825115c5100f 100644
--- a/rust/helpers/xarray.c
+++ b/rust/helpers/xarray.c
@@ -2,27 +2,27 @@
 
 #include <linux/xarray.h>
 
-int rust_helper_xa_err(void *entry)
+__rust_helper int rust_helper_xa_err(void *entry)
 {
 	return xa_err(entry);
 }
 
-void rust_helper_xa_init_flags(struct xarray *xa, gfp_t flags)
+__rust_helper void rust_helper_xa_init_flags(struct xarray *xa, gfp_t flags)
 {
 	return xa_init_flags(xa, flags);
 }
 
-int rust_helper_xa_trylock(struct xarray *xa)
+__rust_helper int rust_helper_xa_trylock(struct xarray *xa)
 {
 	return xa_trylock(xa);
 }
 
-void rust_helper_xa_lock(struct xarray *xa)
+__rust_helper void rust_helper_xa_lock(struct xarray *xa)
 {
 	return xa_lock(xa);
 }
 
-void rust_helper_xa_unlock(struct xarray *xa)
+__rust_helper void rust_helper_xa_unlock(struct xarray *xa)
 {
 	return xa_unlock(xa);
 }

-- 
2.52.0.351.gbe84eed79e-goog

Re: [PATCH v2 10/27] rust: maple_tree: add __rust_helper to helpers

[Liam R. Howlett]

* Alice Ryhl <aliceryhl@google.com> [260105 07:42]:
> This is needed to inline these helpers into Rust code.
> 
> Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
> Acked-by: Andrew Ballance <andrewjballance@gmail.com>
> Reviewed-by: Gary Guo <gary@garyguo.net>
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>

Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>

> ---
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
> Cc: Andrew Ballance <andrewjballance@gmail.com>
> Cc: maple-tree@lists.infradead.org
> Cc: linux-mm@kvack.org
> ---
>  rust/helpers/maple_tree.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/rust/helpers/maple_tree.c b/rust/helpers/maple_tree.c
> index 1dd9ac84a13feed53c0ed5eec6805517081d0673..5586486a76e0de60969af1510b4b0428392920e6 100644
> --- a/rust/helpers/maple_tree.c
> +++ b/rust/helpers/maple_tree.c
> @@ -2,7 +2,8 @@
>  
>  #include <linux/maple_tree.h>
>  
> -void rust_helper_mt_init_flags(struct maple_tree *mt, unsigned int flags)
> +__rust_helper void rust_helper_mt_init_flags(struct maple_tree *mt,
> +					     unsigned int flags)
>  {
>  	mt_init_flags(mt, flags);
>  }
> 
> -- 
> 2.52.0.351.gbe84eed79e-goog
> 

Re: [PATCH v2 11/27] rust: mm: add __rust_helper to helpers

[Liam R. Howlett]

* Alice Ryhl <aliceryhl@google.com> [260105 07:42]:
> This is needed to inline these helpers into Rust code.
> 
> Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
> Reviewed-by: Gary Guo <gary@garyguo.net>
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>

Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>

> ---
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
> Cc: Uladzislau Rezki <urezki@gmail.com>
> Cc: Vitaly Wool <vitaly.wool@konsulko.se>
> Cc: linux-mm@kvack.org
> ---
>  rust/helpers/mm.c      | 20 ++++++++++----------
>  rust/helpers/page.c    |  9 +++++----
>  rust/helpers/vmalloc.c |  2 +-
>  3 files changed, 16 insertions(+), 15 deletions(-)
> 
> diff --git a/rust/helpers/mm.c b/rust/helpers/mm.c
> index 81b510c96fd2692dcb7ab4705f790bd3a41a630e..b5540997bd20d4398e2838956ed70b2fb61c5661 100644
> --- a/rust/helpers/mm.c
> +++ b/rust/helpers/mm.c
> @@ -3,48 +3,48 @@
>  #include <linux/mm.h>
>  #include <linux/sched/mm.h>
>  
> -void rust_helper_mmgrab(struct mm_struct *mm)
> +__rust_helper void rust_helper_mmgrab(struct mm_struct *mm)
>  {
>  	mmgrab(mm);
>  }
>  
> -void rust_helper_mmdrop(struct mm_struct *mm)
> +__rust_helper void rust_helper_mmdrop(struct mm_struct *mm)
>  {
>  	mmdrop(mm);
>  }
>  
> -void rust_helper_mmget(struct mm_struct *mm)
> +__rust_helper void rust_helper_mmget(struct mm_struct *mm)
>  {
>  	mmget(mm);
>  }
>  
> -bool rust_helper_mmget_not_zero(struct mm_struct *mm)
> +__rust_helper bool rust_helper_mmget_not_zero(struct mm_struct *mm)
>  {
>  	return mmget_not_zero(mm);
>  }
>  
> -void rust_helper_mmap_read_lock(struct mm_struct *mm)
> +__rust_helper void rust_helper_mmap_read_lock(struct mm_struct *mm)
>  {
>  	mmap_read_lock(mm);
>  }
>  
> -bool rust_helper_mmap_read_trylock(struct mm_struct *mm)
> +__rust_helper bool rust_helper_mmap_read_trylock(struct mm_struct *mm)
>  {
>  	return mmap_read_trylock(mm);
>  }
>  
> -void rust_helper_mmap_read_unlock(struct mm_struct *mm)
> +__rust_helper void rust_helper_mmap_read_unlock(struct mm_struct *mm)
>  {
>  	mmap_read_unlock(mm);
>  }
>  
> -struct vm_area_struct *rust_helper_vma_lookup(struct mm_struct *mm,
> -					      unsigned long addr)
> +__rust_helper struct vm_area_struct *
> +rust_helper_vma_lookup(struct mm_struct *mm, unsigned long addr)
>  {
>  	return vma_lookup(mm, addr);
>  }
>  
> -void rust_helper_vma_end_read(struct vm_area_struct *vma)
> +__rust_helper void rust_helper_vma_end_read(struct vm_area_struct *vma)
>  {
>  	vma_end_read(vma);
>  }
> diff --git a/rust/helpers/page.c b/rust/helpers/page.c
> index 7144de5a61dbdb3006a668961cd1b09440e74908..f8463fbed2a2670ddfd4c23dc922b46b0913c3a2 100644
> --- a/rust/helpers/page.c
> +++ b/rust/helpers/page.c
> @@ -4,23 +4,24 @@
>  #include <linux/highmem.h>
>  #include <linux/mm.h>
>  
> -struct page *rust_helper_alloc_pages(gfp_t gfp_mask, unsigned int order)
> +__rust_helper struct page *rust_helper_alloc_pages(gfp_t gfp_mask,
> +						   unsigned int order)
>  {
>  	return alloc_pages(gfp_mask, order);
>  }
>  
> -void *rust_helper_kmap_local_page(struct page *page)
> +__rust_helper void *rust_helper_kmap_local_page(struct page *page)
>  {
>  	return kmap_local_page(page);
>  }
>  
> -void rust_helper_kunmap_local(const void *addr)
> +__rust_helper void rust_helper_kunmap_local(const void *addr)
>  {
>  	kunmap_local(addr);
>  }
>  
>  #ifndef NODE_NOT_IN_PAGE_FLAGS
> -int rust_helper_page_to_nid(const struct page *page)
> +__rust_helper int rust_helper_page_to_nid(const struct page *page)
>  {
>  	return page_to_nid(page);
>  }
> diff --git a/rust/helpers/vmalloc.c b/rust/helpers/vmalloc.c
> index 7d7f7336b3d2f5a32e6a2b6cf8407da37775cfd9..326b030487a2b2199283b64b3b427e57cf5fb14a 100644
> --- a/rust/helpers/vmalloc.c
> +++ b/rust/helpers/vmalloc.c
> @@ -2,7 +2,7 @@
>  
>  #include <linux/vmalloc.h>
>  
> -void * __must_check __realloc_size(2)
> +__rust_helper void *__must_check __realloc_size(2)
>  rust_helper_vrealloc_node_align(const void *p, size_t size, unsigned long align,
>  				gfp_t flags, int node)
>  {
> 
> -- 
> 2.52.0.351.gbe84eed79e-goog
> 

Re: [PATCH v2 11/27] rust: mm: add __rust_helper to helpers

[Lorenzo Stoakes]

On Mon, Jan 05, 2026 at 10:10:03AM -0500, Liam R. Howlett wrote:
> * Alice Ryhl <aliceryhl@google.com> [260105 07:42]:
> > This is needed to inline these helpers into Rust code.
> >
> > Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
> > Reviewed-by: Gary Guo <gary@garyguo.net>
> > Signed-off-by: Alice Ryhl <aliceryhl@google.com>
>
> Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>

Seems straightforward enough so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

>
> > ---
> > Cc: Andrew Morton <akpm@linux-foundation.org>
> > Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> > Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
> > Cc: Uladzislau Rezki <urezki@gmail.com>
> > Cc: Vitaly Wool <vitaly.wool@konsulko.se>
> > Cc: linux-mm@kvack.org
> > ---
> >  rust/helpers/mm.c      | 20 ++++++++++----------
> >  rust/helpers/page.c    |  9 +++++----
> >  rust/helpers/vmalloc.c |  2 +-
> >  3 files changed, 16 insertions(+), 15 deletions(-)
> >
> > diff --git a/rust/helpers/mm.c b/rust/helpers/mm.c
> > index 81b510c96fd2692dcb7ab4705f790bd3a41a630e..b5540997bd20d4398e2838956ed70b2fb61c5661 100644
> > --- a/rust/helpers/mm.c
> > +++ b/rust/helpers/mm.c
> > @@ -3,48 +3,48 @@
> >  #include <linux/mm.h>
> >  #include <linux/sched/mm.h>
> >
> > -void rust_helper_mmgrab(struct mm_struct *mm)
> > +__rust_helper void rust_helper_mmgrab(struct mm_struct *mm)
> >  {
> >  	mmgrab(mm);
> >  }
> >
> > -void rust_helper_mmdrop(struct mm_struct *mm)
> > +__rust_helper void rust_helper_mmdrop(struct mm_struct *mm)
> >  {
> >  	mmdrop(mm);
> >  }
> >
> > -void rust_helper_mmget(struct mm_struct *mm)
> > +__rust_helper void rust_helper_mmget(struct mm_struct *mm)
> >  {
> >  	mmget(mm);
> >  }
> >
> > -bool rust_helper_mmget_not_zero(struct mm_struct *mm)
> > +__rust_helper bool rust_helper_mmget_not_zero(struct mm_struct *mm)
> >  {
> >  	return mmget_not_zero(mm);
> >  }
> >
> > -void rust_helper_mmap_read_lock(struct mm_struct *mm)
> > +__rust_helper void rust_helper_mmap_read_lock(struct mm_struct *mm)
> >  {
> >  	mmap_read_lock(mm);
> >  }
> >
> > -bool rust_helper_mmap_read_trylock(struct mm_struct *mm)
> > +__rust_helper bool rust_helper_mmap_read_trylock(struct mm_struct *mm)
> >  {
> >  	return mmap_read_trylock(mm);
> >  }
> >
> > -void rust_helper_mmap_read_unlock(struct mm_struct *mm)
> > +__rust_helper void rust_helper_mmap_read_unlock(struct mm_struct *mm)
> >  {
> >  	mmap_read_unlock(mm);
> >  }
> >
> > -struct vm_area_struct *rust_helper_vma_lookup(struct mm_struct *mm,
> > -					      unsigned long addr)
> > +__rust_helper struct vm_area_struct *
> > +rust_helper_vma_lookup(struct mm_struct *mm, unsigned long addr)
> >  {
> >  	return vma_lookup(mm, addr);
> >  }
> >
> > -void rust_helper_vma_end_read(struct vm_area_struct *vma)
> > +__rust_helper void rust_helper_vma_end_read(struct vm_area_struct *vma)
> >  {
> >  	vma_end_read(vma);
> >  }
> > diff --git a/rust/helpers/page.c b/rust/helpers/page.c
> > index 7144de5a61dbdb3006a668961cd1b09440e74908..f8463fbed2a2670ddfd4c23dc922b46b0913c3a2 100644
> > --- a/rust/helpers/page.c
> > +++ b/rust/helpers/page.c
> > @@ -4,23 +4,24 @@
> >  #include <linux/highmem.h>
> >  #include <linux/mm.h>
> >
> > -struct page *rust_helper_alloc_pages(gfp_t gfp_mask, unsigned int order)
> > +__rust_helper struct page *rust_helper_alloc_pages(gfp_t gfp_mask,
> > +						   unsigned int order)
> >  {
> >  	return alloc_pages(gfp_mask, order);
> >  }
> >
> > -void *rust_helper_kmap_local_page(struct page *page)
> > +__rust_helper void *rust_helper_kmap_local_page(struct page *page)
> >  {
> >  	return kmap_local_page(page);
> >  }
> >
> > -void rust_helper_kunmap_local(const void *addr)
> > +__rust_helper void rust_helper_kunmap_local(const void *addr)
> >  {
> >  	kunmap_local(addr);
> >  }
> >
> >  #ifndef NODE_NOT_IN_PAGE_FLAGS
> > -int rust_helper_page_to_nid(const struct page *page)
> > +__rust_helper int rust_helper_page_to_nid(const struct page *page)
> >  {
> >  	return page_to_nid(page);
> >  }
> > diff --git a/rust/helpers/vmalloc.c b/rust/helpers/vmalloc.c
> > index 7d7f7336b3d2f5a32e6a2b6cf8407da37775cfd9..326b030487a2b2199283b64b3b427e57cf5fb14a 100644
> > --- a/rust/helpers/vmalloc.c
> > +++ b/rust/helpers/vmalloc.c
> > @@ -2,7 +2,7 @@
> >
> >  #include <linux/vmalloc.h>
> >
> > -void * __must_check __realloc_size(2)
> > +__rust_helper void *__must_check __realloc_size(2)
> >  rust_helper_vrealloc_node_align(const void *p, size_t size, unsigned long align,
> >  				gfp_t flags, int node)
> >  {
> >
> > --
> > 2.52.0.351.gbe84eed79e-goog
> >

Re: [PATCH v2 27/27] rust: xarray: add __rust_helper to helpers

[Tamir Duberstein]

On Mon, Jan 5, 2026 at 7:43 AM Alice Ryhl <aliceryhl@google.com> wrote:
>
> This is needed to inline these helpers into Rust code.
>
> Reviewed-by: Boqun Feng <boqun.feng@gmail.com>
> Reviewed-by: Gary Guo <gary@garyguo.net>
> Signed-off-by: Alice Ryhl <aliceryhl@google.com>

Acked-by: Tamir Duberstein <tamird@gmail.com>

> ---
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Matthew Wilcox <willy@infradead.org>
> Cc: Tamir Duberstein <tamird@gmail.com>
> Cc: Andreas Hindborg <a.hindborg@kernel.org>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: linux-mm@kvack.org
> ---
>  rust/helpers/xarray.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/rust/helpers/xarray.c b/rust/helpers/xarray.c
> index 60b299f11451d2c4a75e50e25dec4dac13f143f4..08979b3043410ff89d2adc0b2597825115c5100f 100644
> --- a/rust/helpers/xarray.c
> +++ b/rust/helpers/xarray.c
> @@ -2,27 +2,27 @@
>
>  #include <linux/xarray.h>
>
> -int rust_helper_xa_err(void *entry)
> +__rust_helper int rust_helper_xa_err(void *entry)
>  {
>         return xa_err(entry);
>  }
>
> -void rust_helper_xa_init_flags(struct xarray *xa, gfp_t flags)
> +__rust_helper void rust_helper_xa_init_flags(struct xarray *xa, gfp_t flags)
>  {
>         return xa_init_flags(xa, flags);
>  }
>
> -int rust_helper_xa_trylock(struct xarray *xa)
> +__rust_helper int rust_helper_xa_trylock(struct xarray *xa)
>  {
>         return xa_trylock(xa);
>  }
>
> -void rust_helper_xa_lock(struct xarray *xa)
> +__rust_helper void rust_helper_xa_lock(struct xarray *xa)
>  {
>         return xa_lock(xa);
>  }
>
> -void rust_helper_xa_unlock(struct xarray *xa)
> +__rust_helper void rust_helper_xa_unlock(struct xarray *xa)
>  {
>         return xa_unlock(xa);
>  }
>
> --
> 2.52.0.351.gbe84eed79e-goog
>

Re: [PATCH v2 00/27] Allow inlining C helpers into Rust when using LTO

[Boqun Feng]

On Mon, Jan 05, 2026 at 12:42:13PM +0000, Alice Ryhl wrote:
> This patch series adds __rust_helper to every single rust helper. The
> patches do not depend on each other, so maintainers please go ahead and
> pick up any patches relevant to your subsystem! Or provide your Acked-by
> so that Miguel can pick them up.
> 

I queued the following into rust-sync:

       rust: barrier: add __rust_helper to helpers
       rust: blk: add __rust_helper to helpers
       rust: completion: add __rust_helper to helpers
       rust: cpu: add __rust_helper to helpers
       rust: processor: add __rust_helper to helpers
       rust: rcu: add __rust_helper to helpers
       rust: refcount: add __rust_helper to helpers
       rust: sync: add __rust_helper to helpers
       rust: task: add __rust_helper to helpers
       rust: time: add __rust_helper to helpers
       rust: wait: add __rust_helper to helpers

Thanks!

Regards,
Boqun

> These changes were generated by adding __rust_helper and running
> ClangFormat. Unrelated formatting changes were removed manually.
> 
[...]