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

[Petr Mladek <pmladek@suse.com>]

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
>