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* [PATCH] err.h: use __always_inline on all error pointer helpers
@ 2026-05-26 10:18 Arnd Bergmann
  2026-05-26 15:01 ` Alexander Lobakin
  2026-05-26 19:37 ` Nathan Chancellor
  0 siblings, 2 replies; 8+ messages in thread
From: Arnd Bergmann @ 2026-05-26 10:18 UTC (permalink / raw)
  To: Andrew Morton
  Cc: linux-kbuild, Nathan Chancellor, Nicolas Schier, linux-s390,
	Heiko Carstens, Vasily Gorbik, Alexander Gordeev, Arnd Bergmann,
	Bjorn Andersson, Andy Shevchenko, Christian Marangi, linux-kernel

From: Arnd Bergmann <arnd@arndb.de>

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 ot 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.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 include/linux/err.h | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/linux/err.h b/include/linux/err.h
index 8c37be0620ab..d3e38d5b3a98 100644
--- a/include/linux/err.h
+++ b/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_PTR(long error)
  * @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(__force const void *ptr)
  * @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(__force const void *ptr)
  *
  * 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_OR_NULL(__force const void *ptr)
  * 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_CAST(__force const void *ptr)
  *
  * 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);
-- 
2.39.5


^ permalink raw reply related	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2026-05-27 22:13 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2026-05-26 10:18 [PATCH] err.h: use __always_inline on all error pointer helpers Arnd Bergmann
2026-05-26 15:01 ` Alexander Lobakin
2026-05-26 21:03   ` Arnd Bergmann
2026-05-27 14:06     ` Alexander Lobakin
2026-05-27 14:25       ` Arnd Bergmann
2026-05-27 14:30         ` Alexander Lobakin
2026-05-27 22:13         ` David Laight
2026-05-26 19:37 ` Nathan Chancellor

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