The patch titled Subject: bug: introduce BUILD_BUG_ON_INVALID() macro has been added to the -mm tree. Its filename is bug-introduce-build_bug_on_invalid-macro.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: 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. _ Subject: Subject: bug: introduce BUILD_BUG_ON_INVALID() macro Patches currently in -mm which might be from khlebnikov@xxxxxxxxxx are linux-next.patch proc-pagemap-correctly-report-non-present-ptes-and-holes-between-vmas.patch mm-remove-swap-token-code.patch mm-vmscan-remove-lumpy-reclaim.patch mm-vmscan-do-not-stall-on-writeback-during-memory-compaction.patch mm-vmscan-remove-reclaim_mode_t.patch mm-correctly-synchronize-rss-counters-at-exit-exec.patch kernel-cgroup-push-rcu-read-locking-from-css_is_ancestor-to-callsite.patch mm-memcg-count-pte-references-from-every-member-of-the-reclaimed-hierarchy.patch mm-memcg-count-pte-references-from-every-member-of-the-reclaimed-hierarchy-fix.patch bug-introduce-build_bug_on_invalid-macro.patch bug-completely-remove-code-generated-by-disabled-vm_bug_on.patch mm-memcg-scanning_global_lru-means-mem_cgroup_disabled.patch mm-memcg-move-reclaim_stat-into-lruvec.patch mm-push-lru-index-into-shrink_active_list.patch mm-push-lru-index-into-shrink_active_list-fix.patch mm-mark-mm-inline-functions-as-__always_inline.patch mm-remove-lru-type-checks-from-__isolate_lru_page.patch mm-memcg-kill-mem_cgroup_lru_del.patch mm-memcg-use-vm_swappiness-from-target-memory-cgroup.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 -- 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