From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Triplett Subject: [PATCH v3 4/5] bug: Make BUG() always stop the machine Date: Sun, 9 Mar 2014 18:02:37 -0700 Message-ID: <71630a037c1a76e270e0a5cb8dd7272a73141a08.1394412745.git.josh@joshtriplett.org> References: <17c859aa7dcccec43df0a0c8908911b982764c76.1394412745.git.josh@joshtriplett.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from relay6-d.mail.gandi.net ([217.70.183.198]:39244 "EHLO relay6-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753063AbaCJBCn (ORCPT ); Sun, 9 Mar 2014 21:02:43 -0400 Content-Disposition: inline In-Reply-To: <17c859aa7dcccec43df0a0c8908911b982764c76.1394412745.git.josh@joshtriplett.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Andrew Morton Cc: Arnd Bergmann , linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org When !CONFIG_BUG and !HAVE_ARCH_BUG, define the generic BUG() as an infinite loop rather than a no-op. This avoids undefined behavior if execution ever actually reaches BUG(), and avoids warnings about code after BUG() (such as on non-void functions calling BUG() and then not returning). bloat-o-meter results: add/remove: 0/0 grow/shrink: 43/10 up/down: 235/-98 (137) function old new delta umount_collect 119 138 +19 notify_change 306 324 +18 xstate_enable_boot_cpu 252 269 +17 kunmap 54 70 +16 balloon_page_dequeue 112 126 +14 mm_take_all_locks 223 233 +10 list_lru_walk_node 143 152 +9 vma_adjust 1059 1067 +8 pcpu_setup_first_chunk 1130 1138 +8 mm_drop_all_locks 143 151 +8 ns_capable 55 62 +7 anon_transport_class_unregister 8 15 +7 srcu_init_notifier_head 35 41 +6 shrink_dcache_for_umount 174 180 +6 kunmap_high 99 105 +6 end_page_writeback 43 49 +6 do_exit 1339 1345 +6 __kfifo_dma_out_prepare_r 86 92 +6 __kfifo_dma_in_prepare_r 90 96 +6 fixup_user_fault 120 125 +5 repair_env_string 73 77 +4 read_cache_pages_invalidate_page 56 60 +4 isolate_lru_pages.isra 142 146 +4 do_notify_parent_cldstop 255 259 +4 cpu_init 370 374 +4 utimes_common 270 272 +2 tasklet_hi_action 91 93 +2 tasklet_action 91 93 +2 set_pte_vaddr 46 48 +2 find_get_pages_tag 202 204 +2 early_iounmap 185 187 +2 __native_set_fixmap 36 38 +2 __get_user_pages 822 824 +2 __early_ioremap 299 301 +2 yield_task_stop 1 2 +1 tick_resume 37 38 +1 switched_to_stop 1 2 +1 switched_to_idle 1 2 +1 prio_changed_stop 1 2 +1 prio_changed_idle 1 2 +1 pm_qos_power_read 111 112 +1 arch_cpu_idle_dead 1 2 +1 __insert_vmap_area 140 141 +1 sys_renameat 614 612 -2 mm_fault_error 297 295 -2 SyS_renameat 614 612 -2 sys_linkat 416 413 -3 SyS_linkat 416 413 -3 chmod_common 129 122 -7 proc_cap_handler 240 225 -15 __schedule 849 831 -18 sys_madvise 1077 1054 -23 SyS_madvise 1077 1054 -23 Reported-by: Arnd Bergmann Signed-off-by: Josh Triplett --- v3: New patch in this series, incorporating Arnd's suggestion to make BUG() always stop execution. This eliminates the new warnings currently appearing in allnoconfig due to !CONFIG_BUG; unlike v2, this avoids using unreachable(), and thus avoids the possibility of undefined behvior if execution actually reaches a call to BUG(). include/asm-generic/bug.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/asm-generic/bug.h b/include/asm-generic/bug.h index a97fa11..630dd23 100644 --- a/include/asm-generic/bug.h +++ b/include/asm-generic/bug.h @@ -138,7 +138,7 @@ extern void warn_slowpath_null(const char *file, const int line); #else /* !CONFIG_BUG */ #ifndef HAVE_ARCH_BUG -#define BUG() do {} while (0) +#define BUG() do {} while (1) #endif #ifndef HAVE_ARCH_BUG_ON -- 1.9.0