+ errh-use-__always_inline-on-all-error-pointer-helpers.patch added to mm-nonmm-unstable branch

+ errh-use-__always_inline-on-all-error-pointer-helpers.patch added to mm-nonmm-unstable branch

[Andrew Morton]

The patch titled
     Subject: err.h: use __always_inline on all error pointer helpers
has been added to the -mm mm-nonmm-unstable branch.  Its filename is
     errh-use-__always_inline-on-all-error-pointer-helpers.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/errh-use-__always_inline-on-all-error-pointer-helpers.patch

This patch will later appear in the mm-nonmm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Arnd Bergmann <arnd@arndb.de>
Subject: err.h: use __always_inline on all error pointer helpers
Date: Tue, 26 May 2026 12:18:41 +0200

While testing randconfig builds on s390, I came across a link failure with
CONFIG_DMA_SHARED_BUFFER disabled:

ERROR: modpost: "dma_buf_put" [drivers/iommu/iommufd/iommufd.ko] undefined!

The problem here is that IS_ERR() is not inlined and dead code elimination
fails as a consequence.

The err.h helpers all turn into a trivial assignment of a bit mask and
should never result in a function call, so force them to always be inline.
This should generally result in better object code aside from avoiding
the link failure above.

Link: https://lore.kernel.org/20260526101851.2495110-1-arnd@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Ansuel Smith <ansuelsmth@gmail.com>
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/err.h |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/include/linux/err.h~errh-use-__always_inline-on-all-error-pointer-helpers
+++ a/include/linux/err.h
@@ -36,7 +36,7 @@
  *
  * Return: A pointer with @error encoded within its value.
  */
-static inline void * __must_check ERR_PTR(long error)
+static __always_inline void * __must_check ERR_PTR(long error)
 {
 	return (void *) error;
 }
@@ -60,7 +60,7 @@ static inline void * __must_check ERR_PT
  * @ptr: An error pointer.
  * Return: The error code within @ptr.
  */
-static inline long __must_check PTR_ERR(__force const void *ptr)
+static __always_inline long __must_check PTR_ERR(__force const void *ptr)
 {
 	return (long) ptr;
 }
@@ -73,7 +73,7 @@ static inline long __must_check PTR_ERR(
  * @ptr: The pointer to check.
  * Return: true if @ptr is an error pointer, false otherwise.
  */
-static inline bool __must_check IS_ERR(__force const void *ptr)
+static __always_inline bool __must_check IS_ERR(__force const void *ptr)
 {
 	return IS_ERR_VALUE((unsigned long)ptr);
 }
@@ -87,7 +87,7 @@ static inline bool __must_check IS_ERR(_
  *
  * Like IS_ERR(), but also returns true for a null pointer.
  */
-static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
+static __always_inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
 {
 	return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
 }
@@ -99,7 +99,7 @@ static inline bool __must_check IS_ERR_O
  * Explicitly cast an error-valued pointer to another pointer type in such a
  * way as to make it clear that's what's going on.
  */
-static inline void * __must_check ERR_CAST(__force const void *ptr)
+static __always_inline void * __must_check ERR_CAST(__force const void *ptr)
 {
 	/* cast away the const */
 	return (void *) ptr;
@@ -122,7 +122,7 @@ static inline void * __must_check ERR_CA
  *
  * Return: The error code within @ptr if it is an error pointer; 0 otherwise.
  */
-static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
+static __always_inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
 {
 	if (IS_ERR(ptr))
 		return PTR_ERR(ptr);
_

Patches currently in -mm which might be from arnd@arndb.de are

inith-discard-exitcall-symbols-early.patch
errh-use-__always_inline-on-all-error-pointer-helpers.patch

Re: + errh-use-__always_inline-on-all-error-pointer-helpers.patch added to mm-nonmm-unstable branch

[Andy Shevchenko]

On Tue, May 26, 2026 at 11:40:59AM -0700, Andrew Morton wrote:

> The patch titled
>      Subject: err.h: use __always_inline on all error pointer helpers
> has been added to the -mm mm-nonmm-unstable branch.  Its filename is
>      errh-use-__always_inline-on-all-error-pointer-helpers.patch
> 
> This patch will shortly appear at
>      https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/errh-use-__always_inline-on-all-error-pointer-helpers.patch

Petr, shouldn't this also fix the problem with old (buggy) GCC for xtensa
(IIRC) that we encountered in some tests a couple of months ago?

> ------------------------------------------------------
> From: Arnd Bergmann <arnd@arndb.de>
> Subject: err.h: use __always_inline on all error pointer helpers
> Date: Tue, 26 May 2026 12:18:41 +0200
> 
> While testing randconfig builds on s390, I came across a link failure with
> CONFIG_DMA_SHARED_BUFFER disabled:
> 
> ERROR: modpost: "dma_buf_put" [drivers/iommu/iommufd/iommufd.ko] undefined!
> 
> The problem here is that IS_ERR() is not inlined and dead code elimination
> fails as a consequence.
> 
> The err.h helpers all turn into a trivial assignment of a bit mask and
> should never result in a function call, so force them to always be inline.
> This should generally result in better object code aside from avoiding
> the link failure above.
> 
> Link: https://lore.kernel.org/20260526101851.2495110-1-arnd@kernel.org
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
> Cc: Alexander Gordeev <agordeev@linux.ibm.com>
> Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Ansuel Smith <ansuelsmth@gmail.com>
> Cc: Bjorn Andersson <andersson@kernel.org>
> Cc: Heiko Carstens <hca@linux.ibm.com>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Vasily Gorbik <gor@linux.ibm.com>
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> ---
> 
>  include/linux/err.h |   12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> --- a/include/linux/err.h~errh-use-__always_inline-on-all-error-pointer-helpers
> +++ a/include/linux/err.h
> @@ -36,7 +36,7 @@
>   *
>   * Return: A pointer with @error encoded within its value.
>   */
> -static inline void * __must_check ERR_PTR(long error)
> +static __always_inline void * __must_check ERR_PTR(long error)
>  {
>  	return (void *) error;
>  }
> @@ -60,7 +60,7 @@ static inline void * __must_check ERR_PT
>   * @ptr: An error pointer.
>   * Return: The error code within @ptr.
>   */
> -static inline long __must_check PTR_ERR(__force const void *ptr)
> +static __always_inline long __must_check PTR_ERR(__force const void *ptr)
>  {
>  	return (long) ptr;
>  }
> @@ -73,7 +73,7 @@ static inline long __must_check PTR_ERR(
>   * @ptr: The pointer to check.
>   * Return: true if @ptr is an error pointer, false otherwise.
>   */
> -static inline bool __must_check IS_ERR(__force const void *ptr)
> +static __always_inline bool __must_check IS_ERR(__force const void *ptr)
>  {
>  	return IS_ERR_VALUE((unsigned long)ptr);
>  }
> @@ -87,7 +87,7 @@ static inline bool __must_check IS_ERR(_
>   *
>   * Like IS_ERR(), but also returns true for a null pointer.
>   */
> -static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
> +static __always_inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
>  {
>  	return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
>  }
> @@ -99,7 +99,7 @@ static inline bool __must_check IS_ERR_O
>   * Explicitly cast an error-valued pointer to another pointer type in such a
>   * way as to make it clear that's what's going on.
>   */
> -static inline void * __must_check ERR_CAST(__force const void *ptr)
> +static __always_inline void * __must_check ERR_CAST(__force const void *ptr)
>  {
>  	/* cast away the const */
>  	return (void *) ptr;
> @@ -122,7 +122,7 @@ static inline void * __must_check ERR_CA
>   *
>   * Return: The error code within @ptr if it is an error pointer; 0 otherwise.
>   */
> -static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
> +static __always_inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
>  {
>  	if (IS_ERR(ptr))
>  		return PTR_ERR(ptr);

-- 
With Best Regards,
Andy Shevchenko

Re: + errh-use-__always_inline-on-all-error-pointer-helpers.patch added to mm-nonmm-unstable branch

[Petr Mladek]

Adding Tamir into Cc.

On Tue 2026-06-02 11:36:30, Andy Shevchenko wrote:
> On Tue, May 26, 2026 at 11:40:59AM -0700, Andrew Morton wrote:
> 
> > The patch titled
> >      Subject: err.h: use __always_inline on all error pointer helpers
> > has been added to the -mm mm-nonmm-unstable branch.  Its filename is
> >      errh-use-__always_inline-on-all-error-pointer-helpers.patch
> > 
> > This patch will shortly appear at
> >      https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/errh-use-__always_inline-on-all-error-pointer-helpers.patch
> 
> Petr, shouldn't this also fix the problem with old (buggy) GCC for xtensa
> (IIRC) that we encountered in some tests a couple of months ago?

It might here there as well. Unfortunately, I could not test it easily
because it required some old GCC.

I wonder if Tamir could try to revert the commit 8901ac9d2c7eb8ed
("printf: Compile the kunit test with DISABLE_BRANCH_PROFILING")
and try this patch instead.

Best Regards,
Petr

> > ------------------------------------------------------
> > From: Arnd Bergmann <arnd@arndb.de>
> > Subject: err.h: use __always_inline on all error pointer helpers
> > Date: Tue, 26 May 2026 12:18:41 +0200
> > 
> > While testing randconfig builds on s390, I came across a link failure with
> > CONFIG_DMA_SHARED_BUFFER disabled:
> > 
> > ERROR: modpost: "dma_buf_put" [drivers/iommu/iommufd/iommufd.ko] undefined!
> > 
> > The problem here is that IS_ERR() is not inlined and dead code elimination
> > fails as a consequence.
> > 
> > The err.h helpers all turn into a trivial assignment of a bit mask and
> > should never result in a function call, so force them to always be inline.
> > This should generally result in better object code aside from avoiding
> > the link failure above.
> > 
> > Link: https://lore.kernel.org/20260526101851.2495110-1-arnd@kernel.org
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> > Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
> > Cc: Alexander Gordeev <agordeev@linux.ibm.com>
> > Cc: Andriy Shevchenko <andriy.shevchenko@linux.intel.com>
> > Cc: Ansuel Smith <ansuelsmth@gmail.com>
> > Cc: Bjorn Andersson <andersson@kernel.org>
> > Cc: Heiko Carstens <hca@linux.ibm.com>
> > Cc: Nathan Chancellor <nathan@kernel.org>
> > Cc: Vasily Gorbik <gor@linux.ibm.com>
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
> > ---
> > 
> >  include/linux/err.h |   12 ++++++------
> >  1 file changed, 6 insertions(+), 6 deletions(-)
> > 
> > --- a/include/linux/err.h~errh-use-__always_inline-on-all-error-pointer-helpers
> > +++ a/include/linux/err.h
> > @@ -36,7 +36,7 @@
> >   *
> >   * Return: A pointer with @error encoded within its value.
> >   */
> > -static inline void * __must_check ERR_PTR(long error)
> > +static __always_inline void * __must_check ERR_PTR(long error)
> >  {
> >  	return (void *) error;
> >  }
> > @@ -60,7 +60,7 @@ static inline void * __must_check ERR_PT
> >   * @ptr: An error pointer.
> >   * Return: The error code within @ptr.
> >   */
> > -static inline long __must_check PTR_ERR(__force const void *ptr)
> > +static __always_inline long __must_check PTR_ERR(__force const void *ptr)
> >  {
> >  	return (long) ptr;
> >  }
> > @@ -73,7 +73,7 @@ static inline long __must_check PTR_ERR(
> >   * @ptr: The pointer to check.
> >   * Return: true if @ptr is an error pointer, false otherwise.
> >   */
> > -static inline bool __must_check IS_ERR(__force const void *ptr)
> > +static __always_inline bool __must_check IS_ERR(__force const void *ptr)
> >  {
> >  	return IS_ERR_VALUE((unsigned long)ptr);
> >  }
> > @@ -87,7 +87,7 @@ static inline bool __must_check IS_ERR(_
> >   *
> >   * Like IS_ERR(), but also returns true for a null pointer.
> >   */
> > -static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
> > +static __always_inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
> >  {
> >  	return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
> >  }
> > @@ -99,7 +99,7 @@ static inline bool __must_check IS_ERR_O
> >   * Explicitly cast an error-valued pointer to another pointer type in such a
> >   * way as to make it clear that's what's going on.
> >   */
> > -static inline void * __must_check ERR_CAST(__force const void *ptr)
> > +static __always_inline void * __must_check ERR_CAST(__force const void *ptr)
> >  {
> >  	/* cast away the const */
> >  	return (void *) ptr;
> > @@ -122,7 +122,7 @@ static inline void * __must_check ERR_CA
> >   *
> >   * Return: The error code within @ptr if it is an error pointer; 0 otherwise.
> >   */
> > -static inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
> > +static __always_inline int __must_check PTR_ERR_OR_ZERO(__force const void *ptr)
> >  {
> >  	if (IS_ERR(ptr))
> >  		return PTR_ERR(ptr);
> 
> -- 
> With Best Regards,
> Andy Shevchenko
> 

Re: + errh-use-__always_inline-on-all-error-pointer-helpers.patch added to mm-nonmm-unstable branch

[Tamir Duberstein]

On Tue, Jun 2, 2026 at 8:41 AM Petr Mladek <pmladek@suse.com> wrote:
>
> Adding Tamir into Cc.
>
> On Tue 2026-06-02 11:36:30, Andy Shevchenko wrote:
> > On Tue, May 26, 2026 at 11:40:59AM -0700, Andrew Morton wrote:
> >
> > > The patch titled
> > >      Subject: err.h: use __always_inline on all error pointer helpers
> > > has been added to the -mm mm-nonmm-unstable branch.  Its filename is
> > >      errh-use-__always_inline-on-all-error-pointer-helpers.patch
> > >
> > > This patch will shortly appear at
> > >      https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/errh-use-__always_inline-on-all-error-pointer-helpers.patch
> >
> > Petr, shouldn't this also fix the problem with old (buggy) GCC for xtensa
> > (IIRC) that we encountered in some tests a couple of months ago?
>
> It might here there as well. Unfortunately, I could not test it easily
> because it required some old GCC.
>
> I wonder if Tamir could try to revert the commit 8901ac9d2c7eb8ed
> ("printf: Compile the kunit test with DISABLE_BRANCH_PROFILING")
> and try this patch instead.

Yes, confirmed.

I rebuilt xtensa-linux GCC 8.5.0 and tested printf_kunit.c with the original
randconfig and branch profiling enabled, without DISABLE_BRANCH_PROFILING.

Without Arnd's patch, the original failure reproduces:

printf_kunit.c: In function 'errptr.part.2': error: call to
'__compiletime_assert_313' declared with attribute error: BUILD_BUG_ON failed:
IS_ERR(PTR)

With "err.h: use __always_inline on all error pointer helpers" applied, the same
compile succeeds.

So Arnd's patch fixes this case and commit 8901ac9d2c7e ("printf: Compile the
kunit test with DISABLE_BRANCH_PROFILING") can be reverted once it lands.