Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Tong Zhang <ztong0001@gmail.com>
To:     Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org,
        linux-kernel@vger.kernel.org, llvm@lists.linux.dev
Cc:     Tong Zhang <ztong0001@gmail.com>
Subject: [PATCH v2] drm/i915: fix build issue when using clang
Date:   Mon, 14 Feb 2022 11:58:20 -0800
Message-Id: <20220214195821.29809-1-ztong0001@gmail.com>
In-Reply-To: <YglQW7gVNoRJ7QpQ@dev-arch.archlinux-ax161>
References: <YglQW7gVNoRJ7QpQ@dev-arch.archlinux-ax161>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

drm/i915 adds some extra cflags, namely -Wall, which causes
instances of -Wformat-security to appear when building with clang, even
though this warning is turned off kernel-wide in the main Makefile:

> drivers/gpu/drm/i915/gt/intel_gt.c:983:2: error: format string is not a string literal (potentially insecure) [-Werror,-Wformat-security]
>         GEM_TRACE("ERROR\n");
>         ^~~~~~~~~~~~~~~~~~~~
> ./drivers/gpu/drm/i915/i915_gem.h:76:24: note: expanded from macro 'GEM_TRACE'
>  #define GEM_TRACE(...) trace_printk(__VA_ARGS__)
>                        ^~~~~~~~~~~~~~~~~~~~~~~~~
> ./include/linux/kernel.h:369:3: note: expanded from macro 'trace_printk'
>                 do_trace_printk(fmt, ##__VA_ARGS__);    \
>                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> ./include/linux/kernel.h:383:30: note: expanded from macro 'do_trace_printk'
>                 __trace_bprintk(_THIS_IP_, trace_printk_fmt, ##args);   \
>                                           ^~~~~~~~~~~~~~~~
>drivers/gpu/drm/i915/gt/intel_gt.c:983:2: note: treat the string as an argument to avoid this

This does not happen with GCC because it does not enable
-Wformat-security with -Wall. Disable -Wformat-security within the i915
Makefile so that these warnings do not show up with clang.

Signed-off-by: Tong Zhang <ztong0001@gmail.com>
---

v2: revise commit message

 drivers/gpu/drm/i915/Makefile | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
index 1b62b9f65196..c04e05a3d39f 100644
--- a/drivers/gpu/drm/i915/Makefile
+++ b/drivers/gpu/drm/i915/Makefile
@@ -13,6 +13,7 @@
 # will most likely get a sudden build breakage... Hopefully we will fix
 # new warnings before CI updates!
 subdir-ccflags-y := -Wall -Wextra
+subdir-ccflags-y += -Wno-format-security
 subdir-ccflags-y += -Wno-unused-parameter
 subdir-ccflags-y += -Wno-type-limits
 subdir-ccflags-y += -Wno-missing-field-initializers
-- 
2.25.1