[PATCH] Disable -Wframe-larger-than warnings with KASAN=y

From	Andrey Ryabinin <aryabinin@virtuozzo.com>
Newsgroups	linux.kernel
Subject	[PATCH] Disable -Wframe-larger-than warnings with KASAN=y
Date	2015-10-16 18:10 +0200
Message-ID	<qkfJU-2V2-13@gated-at.bofh.it> (permalink)
References	<qgbOx-5x8-3@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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When the kernel compiled with KASAN=y, GCC adds redzones
for each variable on stack. This enlarges function's stack
frame and causes:
	'warning: the frame size of X bytes is larger than Y bytes'

The worst case I've seen for now is following:
 ../net/wireless/nl80211.c: In function ‘nl80211_send_wiphy’:
 ../net/wireless/nl80211.c:1731:1: warning: the frame size of 5448 bytes is larger than 2048 bytes [-Wframe-larger-than=]
  }
   ^
That kind of warning becomes useless with KASAN=y. It doesn't necessarily
indicate that there is some problem in the code, thus we should turn it off.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
 lib/Kconfig.debug | 1 +
 1 file changed, 1 insertion(+)

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index ab76b99..1d1521c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -197,6 +197,7 @@ config ENABLE_MUST_CHECK
 config FRAME_WARN
 	int "Warn for stack frames larger than (needs gcc 4.4)"
 	range 0 8192
+	default 0 if KASAN
 	default 1024 if !64BIT
 	default 2048 if 64BIT
 	help
-- 
2.4.9

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[PATCH] Disable -Wframe-larger-than warnings with KASAN=y Andrey Ryabinin <aryabinin@virtuozzo.com> - 2015-10-16 18:10 +0200
  Re: [PATCH] Disable -Wframe-larger-than warnings with KASAN=y Andi Kleen <ak@linux.intel.com> - 2015-10-16 18:50 +0200
    Re: [PATCH] Disable -Wframe-larger-than warnings with KASAN=y Andrey Ryabinin <ryabinin.a.a@gmail.com> - 2015-10-16 19:20 +0200

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