The patch titled
Subject: compiler, clang: always inline when CONFIG_OPTIMIZE_INLINING is disabled
has been added to the -mm tree. Its filename is
compiler-clang-always-inline-when-config_optimize_inlining-is-disabled.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/compiler-clang-always-inline-when-config_optimize_inlining-is-disabled.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/compiler-clang-always-inline-when-config_optimize_inlining-is-disabled.patch
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/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: David Rientjes <rientjes@xxxxxxxxxx>
Subject: compiler, clang: always inline when CONFIG_OPTIMIZE_INLINING is disabled
The motivation of abb2ea7dfd82 ("compiler, clang: suppress warning for
unused static inline functions") is to suppress clang's warnings about
unused static inline functions.
For configs without CONFIG_OPTIMIZE_INLINING enabled, such as any non-x86
architecture, `inline' in the kernel implies that
__attribute__((always_inline)) is used.
Some code depends on that behavior, see
https://lkml.org/lkml/2017/6/13/918:
net/built-in.o: In function `__xchg_mb':
arch/arm64/include/asm/cmpxchg.h:99: undefined reference to `__compiletime_assert_99'
arch/arm64/include/asm/cmpxchg.h:99: undefined reference to `__compiletime_assert_99
The full fix would be to identify these breakages and annotate the
functions with __always_inline instead of `inline'. But since we are late
in the 4.12-rc cycle, simply carry forward the forced inlining behavior
and work toward moving arm64, and other architectures, toward
CONFIG_OPTIMIZE_INLINING behavior.
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1706261552200.1075@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Reported-by: Sodagudi Prasad <psodagud@xxxxxxxxxxxxxx>
Tested-by: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Will Deacon <will.deacon@xxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/compiler-clang.h | 8 --------
include/linux/compiler-gcc.h | 18 +++++++++++-------
2 files changed, 11 insertions(+), 15 deletions(-)
diff -puN include/linux/compiler-clang.h~compiler-clang-always-inline-when-config_optimize_inlining-is-disabled include/linux/compiler-clang.h
--- a/include/linux/compiler-clang.h~compiler-clang-always-inline-when-config_optimize_inlining-is-disabled
+++ a/include/linux/compiler-clang.h
@@ -15,11 +15,3 @@
* with any version that can compile the kernel
*/
#define __UNIQUE_ID(prefix) __PASTE(__PASTE(__UNIQUE_ID_, prefix), __COUNTER__)
-
-/*
- * GCC does not warn about unused static inline functions for
- * -Wunused-function. This turns out to avoid the need for complex #ifdef
- * directives. Suppress the warning in clang as well.
- */
-#undef inline
-#define inline inline __attribute__((unused)) notrace
diff -puN include/linux/compiler-gcc.h~compiler-clang-always-inline-when-config_optimize_inlining-is-disabled include/linux/compiler-gcc.h
--- a/include/linux/compiler-gcc.h~compiler-clang-always-inline-when-config_optimize_inlining-is-disabled
+++ a/include/linux/compiler-gcc.h
@@ -66,18 +66,22 @@
/*
* Force always-inline if the user requests it so via the .config,
- * or if gcc is too old:
+ * or if gcc is too old.
+ * GCC does not warn about unused static inline functions for
+ * -Wunused-function. This turns out to avoid the need for complex #ifdef
+ * directives. Suppress the warning in clang as well by using "unused"
+ * function attribute, which is redundant but not harmful for gcc.
*/
#if !defined(CONFIG_ARCH_SUPPORTS_OPTIMIZED_INLINING) || \
!defined(CONFIG_OPTIMIZE_INLINING) || (__GNUC__ < 4)
-#define inline inline __attribute__((always_inline)) notrace
-#define __inline__ __inline__ __attribute__((always_inline)) notrace
-#define __inline __inline __attribute__((always_inline)) notrace
+#define inline inline __attribute__((always_inline,unused)) notrace
+#define __inline__ __inline__ __attribute__((always_inline,unused)) notrace
+#define __inline __inline __attribute__((always_inline,unused)) notrace
#else
/* A lot of inline functions can cause havoc with function tracing */
-#define inline inline notrace
-#define __inline__ __inline__ notrace
-#define __inline __inline notrace
+#define inline inline __attribute__((unused)) notrace
+#define __inline__ __inline__ __attribute__((unused)) notrace
+#define __inline __inline __attribute__((unused)) notrace
#endif
#define __always_inline inline __attribute__((always_inline))
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
compiler-clang-always-inline-when-config_optimize_inlining-is-disabled.patch
mm-vmscan-avoid-thrashing-anon-lru-when-free-file-is-low.patch
mm-vmpressure-pass-through-notification-support.patch
mm-hugetlb-schedule-when-potentially-allocating-many-hugepages.patch
fs-epoll-short-circuit-fetching-events-if-thread-has-been-killed.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
