Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760749AbbLCPu3 (ORCPT ); Thu, 3 Dec 2015 10:50:29 -0500 Received: from relay.parallels.com ([195.214.232.42]:44577 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760615AbbLCPuY (ORCPT ); Thu, 3 Dec 2015 10:50:24 -0500 From: Andrey Ryabinin To: CC: Andrey Ryabinin , , , Johannes Berg , "David S. Miller" , Andrew Morton , Peter Zijlstra , Sasha Levin , Randy Dunlap , Rasmus Villemoes , Jonathan Corbet , Michal Marek , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Yury Gribov , Dmitry Vyukov , Konstantin Khlebnikov , Kostya Serebryany , , , Subject: [PATCH v4 2/3] mac80211: Prevent build failure with CONFIG_UBSAN=y Date: Thu, 3 Dec 2015 18:50:06 +0300 Message-ID: <1449157807-20298-3-git-send-email-aryabinin@virtuozzo.com> X-Mailer: git-send-email 2.4.10 In-Reply-To: <1449157807-20298-1-git-send-email-aryabinin@virtuozzo.com> References: <1449157807-20298-1-git-send-email-aryabinin@virtuozzo.com> MIME-Version: 1.0 Content-Type: text/plain X-ClientProxiedBy: US-EXCH.sw.swsoft.com (10.255.249.47) To MSK-EXCH1.sw.swsoft.com (10.67.48.55) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2326 Lines: 63 With upcoming CONFIG_UBSAN the following BUILD_BUG_ON in net/mac80211/debugfs.c starts to trigger: BUILD_BUG_ON(hw_flag_names[NUM_IEEE80211_HW_FLAGS] != (void *)0x1); It seems, that compiler instrumentation causes some code deoptimizations. Because of that GCC is not being able to resolve condition in BUILD_BUG_ON() at compile time. We could make size of hw_flag_names array unspecified and replace the condition in BUILD_BUG_ON() with following: ARRAY_SIZE(hw_flag_names) != NUM_IEEE80211_HW_FLAGS That will have the same effect as before (adding new flag without updating array will trigger build failure) except it doesn't fail with CONFIG_UBSAN. As a bonus this patch slightly decreases size of hw_flag_names array. Signed-off-by: Andrey Ryabinin Cc: Johannes Berg Cc: "David S. Miller" --- net/mac80211/debugfs.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/net/mac80211/debugfs.c b/net/mac80211/debugfs.c index abbdff0..3e24d0d 100644 --- a/net/mac80211/debugfs.c +++ b/net/mac80211/debugfs.c @@ -91,7 +91,7 @@ static const struct file_operations reset_ops = { }; #endif -static const char *hw_flag_names[NUM_IEEE80211_HW_FLAGS + 1] = { +static const char *hw_flag_names[] = { #define FLAG(F) [IEEE80211_HW_##F] = #F FLAG(HAS_RATE_CONTROL), FLAG(RX_INCLUDES_FCS), @@ -126,9 +126,6 @@ static const char *hw_flag_names[NUM_IEEE80211_HW_FLAGS + 1] = { FLAG(SUPPORTS_AMSDU_IN_AMPDU), FLAG(BEACON_TX_STATUS), FLAG(NEEDS_UNIQUE_STA_ADDR), - - /* keep last for the build bug below */ - (void *)0x1 #undef FLAG }; @@ -148,7 +145,7 @@ static ssize_t hwflags_read(struct file *file, char __user *user_buf, /* fail compilation if somebody adds or removes * a flag without updating the name array above */ - BUILD_BUG_ON(hw_flag_names[NUM_IEEE80211_HW_FLAGS] != (void *)0x1); + BUILD_BUG_ON(ARRAY_SIZE(hw_flag_names) != NUM_IEEE80211_HW_FLAGS); for (i = 0; i < NUM_IEEE80211_HW_FLAGS; i++) { if (test_bit(i, local->hw.flags)) -- 2.4.10 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/