The patch titled
Subject: bug: introduce BUILD_BUG_ON_INVALID() macro
has been removed from the -mm tree. Its filename was
bug-introduce-build_bug_on_invalid-macro.patch
This patch was dropped because it was merged into mainline or a subsystem tree
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
From: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
Subject: bug: introduce BUILD_BUG_ON_INVALID() macro
Sometimes we want to check some expressions correctness at compile time.
"(void)(e);" or "if (e);" can be dangerous if the expression has
side-effects, and gcc sometimes generates a lot of code, even if the
expression has no effect.
This patch introduces macro BUILD_BUG_ON_INVALID() for such checks, it
forces a compilation error if expression is invalid without any extra
code.
[Cast to "long" required because sizeof does not work for bit-fields.]
Signed-off-by: Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Cong Wang <xiyou.wangcong@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/bug.h | 7 +++++++
1 file changed, 7 insertions(+)
diff -puN include/linux/bug.h~bug-introduce-build_bug_on_invalid-macro include/linux/bug.h
--- a/include/linux/bug.h~bug-introduce-build_bug_on_invalid-macro
+++ a/include/linux/bug.h
@@ -30,6 +30,13 @@ struct pt_regs;
#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
+/*
+ * BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the
+ * expression but avoids the generation of any code, even if that expression
+ * has side-effects.
+ */
+#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
+
/**
* BUILD_BUG_ON - break compile if a condition is true.
* @condition: the condition which the compiler should know is false.
_
Patches currently in -mm which might be from khlebnikov@xxxxxxxxxx are
origin.patch
linux-next.patch
mm-correctly-synchronize-rss-counters-at-exit-exec.patch
proc-report-file-anon-bit-in-proc-pid-pagemap.patch
proc-smaps-carefully-handle-migration-entries.patch
proc-smaps-show-amount-of-nonlinear-ptes-in-vma.patch
proc-smaps-show-amount-of-hwpoison-pages.patch
fork-call-complete_vfork_done-after-clearing-child_tid-and-flushing-rss-counters.patch
c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal.patch
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