err.h: use __always_inline on all error pointer helpers

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>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Tamir Duberstein <tamird@kernel.org>
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: Vasily Gorbik <gor@linux.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/err.h b/include/linux/err.h
index 8c37be0620abfc6738b56419a41e88f8f9d767d2..d3e38d5b3a985b016d25dc000d29bb9034c87cf5 100644 (file)
--- 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);