From 68920c973254c5b71a684645c5f6f82d6732c5d6 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Wed, 20 Jan 2016 15:00:51 -0800 Subject: [PATCH] net/mac80211/debugfs.c: prevent build failure with CONFIG_UBSAN=y 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" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 abbdff03ce92..3e24d0ddb51b 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)) -- 2.45.2