The patch titled
compiler: introduce __used and __maybe_unused
has been added to the -mm tree. Its filename is
compiler-introduce-__used-and-__maybe_unused.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: compiler: introduce __used and __maybe_unused
From: David Rientjes <rientjes@xxxxxxxxxx>
__used is defined to be __attribute__((unused)) for all pre-3.3 gcc
compilers to suppress warnings for unused functions because perhaps they
are referenced only in inline assembly. It is defined to be
__attribute__((used)) for gcc 3.3 and later so that the code is still
emitted for such functions.
__maybe_unused is defined to be __attribute__((unused)) for both function
and variable use if it could possibly be unreferenced due to the evaluation
of preprocessor macros. Function prototypes shall be marked with
__maybe_unused if the actual definition of the function is dependant on
preprocessor macros.
No update to compiler-intel.h is necessary because ICC supports both
__attribute__((used)) and __attribute__((unused)) as specified by the gcc
manual.
__attribute_used__ is deprecated and will be removed once all current
code is converted to using __used.
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Adrian Bunk <bunk@xxxxxxxxx>
Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/compiler-gcc.h | 1 +
include/linux/compiler-gcc3.h | 6 ++++--
include/linux/compiler-gcc4.h | 3 ++-
include/linux/compiler.h | 21 ++++++++++++++++++---
4 files changed, 25 insertions(+), 6 deletions(-)
diff -puN include/linux/compiler-gcc.h~compiler-introduce-__used-and-__maybe_unused include/linux/compiler-gcc.h
--- a/include/linux/compiler-gcc.h~compiler-introduce-__used-and-__maybe_unused
+++ a/include/linux/compiler-gcc.h
@@ -40,3 +40,4 @@
#define noinline __attribute__((noinline))
#define __attribute_pure__ __attribute__((pure))
#define __attribute_const__ __attribute__((__const__))
+#define __maybe_unused __attribute__((unused))
diff -puN include/linux/compiler-gcc3.h~compiler-introduce-__used-and-__maybe_unused include/linux/compiler-gcc3.h
--- a/include/linux/compiler-gcc3.h~compiler-introduce-__used-and-__maybe_unused
+++ a/include/linux/compiler-gcc3.h
@@ -4,9 +4,11 @@
#include <linux/compiler-gcc.h>
#if __GNUC_MINOR__ >= 3
-# define __attribute_used__ __attribute__((__used__))
+# define __used __attribute__((__used__))
+# define __attribute_used__ __used /* deprecated */
#else
-# define __attribute_used__ __attribute__((__unused__))
+# define __used __attribute__((__unused__))
+# define __attribute_used__ __used /* deprecated */
#endif
#if __GNUC_MINOR__ >= 4
diff -puN include/linux/compiler-gcc4.h~compiler-introduce-__used-and-__maybe_unused include/linux/compiler-gcc4.h
--- a/include/linux/compiler-gcc4.h~compiler-introduce-__used-and-__maybe_unused
+++ a/include/linux/compiler-gcc4.h
@@ -12,7 +12,8 @@
# define __inline __inline __attribute__((always_inline))
#endif
-#define __attribute_used__ __attribute__((__used__))
+#define __used __attribute__((__used__))
+#define __attribute_used__ __used /* deprecated */
#define __must_check __attribute__((warn_unused_result))
#define __compiler_offsetof(a,b) __builtin_offsetof(a,b)
#define __always_inline inline __attribute__((always_inline))
diff -puN include/linux/compiler.h~compiler-introduce-__used-and-__maybe_unused include/linux/compiler.h
--- a/include/linux/compiler.h~compiler-introduce-__used-and-__maybe_unused
+++ a/include/linux/compiler.h
@@ -108,15 +108,30 @@ extern void __chk_io_ptr(const void __io
* Allow us to avoid 'defined but not used' warnings on functions and data,
* as well as force them to be emitted to the assembly file.
*
- * As of gcc 3.3, static functions that are not marked with attribute((used))
- * may be elided from the assembly file. As of gcc 3.3, static data not so
+ * As of gcc 3.4, static functions that are not marked with attribute((used))
+ * may be elided from the assembly file. As of gcc 3.4, static data not so
* marked will not be elided, but this may change in a future gcc version.
*
+ * NOTE: Because distributions shipped with a backported unit-at-a-time
+ * compiler in gcc 3.3, we must define __used to be __attribute__((used))
+ * for gcc >=3.3 instead of 3.4.
+ *
* In prior versions of gcc, such functions and data would be emitted, but
* would be warned about except with attribute((unused)).
+ *
+ * Mark functions that are referenced only in inline assembly as __used so
+ * the code is emitted even though it appears to be unreferenced.
*/
#ifndef __attribute_used__
-# define __attribute_used__ /* unimplemented */
+# define __attribute_used__ /* deprecated */
+#endif
+
+#ifndef __used
+# define __used /* unimplemented */
+#endif
+
+#ifndef __maybe_unused
+# define __maybe_unused /* unimplemented */
#endif
/*
_
Patches currently in -mm which might be from rientjes@xxxxxxxxxx are
origin.patch
i386-add-ptep_test_and_clear_dirtyyoung.patch
i386-use-pte_update_defer-in-ptep_test_and_clear_dirtyyoung.patch
smaps-extract-pmd-walker-from-smaps-code.patch
smaps-add-pages-referenced-count-to-smaps.patch
smaps-add-clear_refs-file-to-clear-reference.patch
cpusets-allow-tif_memdie-threads-to-allocate-anywhere.patch
mm-fix-handling-of-panic_on_oom-when-cpusets-are-in-use.patch
oom-fix-constraint-deadlock.patch
wavefront-only-declare-isapnp-on-config_pnp.patch
git-cpufreq.patch
maps2-uninline-some-functions-in-the-page-walker.patch
maps2-eliminate-the-pmd_walker-struct-in-the-page-walker.patch
maps2-remove-vma-from-args-in-the-page-walker.patch
maps2-propagate-errors-from-callback-in-page-walker.patch
maps2-add-callbacks-for-each-level-to-page-walker.patch
maps2-move-the-page-walker-code-to-lib.patch
maps2-simplify-interdependence-of-proc-pid-maps-and-smaps.patch
maps2-move-clear_refs-code-to-task_mmuc.patch
maps2-regroup-task_mmu-by-interface.patch
maps2-make-proc-pid-smaps-optional-under-config_embedded.patch
maps2-make-proc-pid-clear_refs-option-under-config_embedded.patch
maps2-add-proc-pid-pagemap-interface.patch
maps2-add-proc-kpagemap-interface.patch
cpusets-allow-empty-cpusmems_allowed-to-be-set-for.patch
cpusets-allow-empty-cpusmems_allowed-to-be-set-for-fix.patch
compiler-introduce-__used-and-__maybe_unused.patch
i386-pci-type-may-be-unused.patch
sh-dma-use-__attribute_unused__.patch
scsi-fix-ambiguous-gdthtable-definition.patch
frv-gdb-use-__attribute_unused__.patch
i386-voyager-use-__attribute_unused__.patch
mips-excite-use-__attribute_unused__.patch
mips-tlbex-use-__attribute_unused__.patch
powerpc-ps3-use-__attribute_unused__.patch
i386-mmzone-use-__attribute_unused__.patch
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