Linux: -Wuninitialized in drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c

Created on 16 Oct 2018 · 9Comments · Source: ClangBuiltLinux/linux

drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c:350:34: error: variable 'wq' is uninitialized when used within its own initialization [-Werror,-Wuninitialized]
        DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
                                        ^~
./include/linux/wait.h:74:63: note: expanded from macro 'DECLARE_WAIT_QUEUE_HEAD_ONSTACK'
        struct wait_queue_head name = __WAIT_QUEUE_HEAD_INIT_ONSTACK(name)
                               ~~~~                                  ^~~~
./include/linux/wait.h:72:33: note: expanded from macro '__WAIT_QUEUE_HEAD_INIT_ONSTACK'
        ({ init_waitqueue_head(&name); name; })
                                       ^~~~
1 error generated.

allyesconfig on x86_64

-Wuninitialized [ARCH] x86_64 [BUG] linux [FIXED][LINUX] 5.1

Source

nathanchance

All 9 comments

Ah I see what's going on here.

-Wuninitialized is disabled in scripts/Makefile.extrawarn when W= is not provided to make but drivers/gpu/drm/i915/Makefile calls -Wall after, which re-enables it.

/usr/bin/ccache clang -Wp,-MD,drivers/gpu/drm/i915/.intel_uc.o.d  -nostdinc -isystem /home/nathan/toolchains/clang-8.x/lib/clang/8.0.344477/include -I./arch/x86/include -I./arch/x86/include/generated  -I./include -I./arch/x86/include/uapi -I./arch/x86/include/generated/uapi -I./include/uapi -I./include/generated/uapi -include ./include/linux/kconfig.h -include ./include/linux/compiler_types.h -D__KERNEL__ -Qunused-arguments -Wall -Wundef -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common -fshort-wchar -Werror-implicit-function-declaration -Wno-format-security -std=gnu89 -no-integrated-as -fno-PIE -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx -m64 -mno-80387 -mstack-alignment=8 -mtune=generic -mno-red-zone -mcmodel=kernel -funit-at-a-time -DCONFIG_X86_X32_ABI -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -DCONFIG_AS_CFI_SECTIONS=1 -DCONFIG_AS_FXSAVEQ=1 -DCONFIG_AS_SSSE3=1 -DCONFIG_AS_AVX=1 -DCONFIG_AS_AVX2=1 -DCONFIG_AS_AVX512=1 -DCONFIG_AS_SHA1_NI=1 -DCONFIG_AS_SHA256_NI=1 -pipe -Wno-sign-compare -fno-asynchronous-unwind-tables -mretpoline-external-thunk -DRETPOLINE -Wa,arch/x86/kernel/macros.s -D__BPF_TRACING__ -fno-delete-null-pointer-checks -O2 -fstack-protector-strong -Wno-format-invalid-specifier -Wno-gnu -Wno-address-of-packed-member -Wno-tautological-compare -Wno-switch -mno-global-merge -Wno-unused-const-variable -pg -mfentry -DCC_USING_FENTRY -Wdeclaration-after-statement -Wvla -Wno-pointer-sign -fno-strict-overflow -fno-merge-all-constants -fno-stack-check -Werror=implicit-int -Werror=strict-prototypes -Werror=date-time -Werror=incompatible-pointer-types -Wno-constant-conversion -Wno-empty-body -Wno-initializer-overrides -Wno-unused-value -Wno-format -Wno-sign-compare -Wno-format-zero-length -Wno-uninitialized -Werror -Wall -Wextra -Wno-unused-parameter -Wno-type-limits -Wno-missing-field-initializers -Wno-implicit-fallthrough -Wno-sign-compare -Wno-sometimes-uninitialized -Wno-initializer-overrides -DCONFIG_AS_MOVNTDQA -Idrivers/gpu/drm/i915 -Idrivers/gpu/drm/i915/gvt    -fsanitize=kernel-address -mllvm -asan-mapping-offset=0xdffffc0000000000  -mllvm -asan-globals=1  -mllvm -asan-instrumentation-with-call-threshold=0  -mllvm -asan-stack=1  -mllvm -asan-use-after-scope=1   --param asan-instrument-allocas=1   -fsanitize-coverage=trace-pc -fsanitize-coverage=trace-cmp    -DKBUILD_BASENAME='"intel_uc"' -DKBUILD_MODNAME='"i915"' -c -o drivers/gpu/drm/i915/.tmp_intel_uc.o drivers/gpu/drm/i915/intel_uc.c

Not sure if the warning should be fixed or hidden again.

nathanchance on 16 Oct 2018

Probably hidden again. I think I had sent the i915 folks a patch like this before (about -Wall re-enabling things that were disabled).