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-Wuninitialized in drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c #220

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nathanchance opened this issue Oct 15, 2018 · 9 comments
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-Wuninitialized in drivers/gpu/drm/i915/selftests/intel_breadcrumbs.c #220

nathanchance opened this issue Oct 15, 2018 · 9 comments
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@nathanchance
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-Wuninitialized [ARCH] x86_64 This bug impacts ARCH=x86_64 [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.1 This bug was fixed in Linux 5.1

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@nathanchance
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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
@nathanchance nathanchance added [BUG] Untriaged Something isn't working [ARCH] x86_64 This bug impacts ARCH=x86_64 -Wuninitialized labels Oct 15, 2018
@nathanchance
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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.

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

@nickdesaulniers nickdesaulniers added [BUG] linux A bug that should be fixed in the mainline kernel. low priority This bug is not critical and not a priority and removed [BUG] Untriaged Something isn't working labels Oct 25, 2018
@nathanchance
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Will send it shortly then, thanks!

@nathanchance
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Patch sent: https://lore.kernel.org/lkml/20181025193601.11746-1-natechancellor@gmail.com/

@nathanchance nathanchance added the [PATCH] Submitted A patch has been submitted for review label Oct 25, 2018
@nathanchance nathanchance mentioned this issue Jan 18, 2019
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@nickdesaulniers
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@nathanchance can you please send a v2 disabling the warning for the whole subdir?

@nathanchance
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v2: https://lore.kernel.org/lkml/20190126071122.24557-1-natechancellor@gmail.com/

@nathanchance
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Patch accepted: https://cgit.freedesktop.org/drm/drm-intel/commit/?id=c5627461490e4b913e8747d3b06541e5264a50d7

@nathanchance nathanchance added [PATCH] Accepted A submitted patch has been accepted upstream and removed [PATCH] Submitted A patch has been submitted for review labels Jan 26, 2019
@nickdesaulniers
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The patch was so nice, I reviewed it twice! 🥁

@nathanchance
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Merged into mainline: https://git.kernel.org/torvalds/c/c5627461490e4b913e8747d3b06541e5264a50d7

@nathanchance nathanchance added [FIXED][LINUX] 5.1 This bug was fixed in Linux 5.1 and removed [PATCH] Accepted A submitted patch has been accepted upstream low priority This bug is not critical and not a priority labels Mar 8, 2019
fengguang pushed a commit to 0day-ci/linux that referenced this issue Feb 16, 2021
@nathanchance @intel-lab-lkp
drm/i915: Enable -Wuninitialized
044fed5 
-Wunintialized was disabled in commit c562746 ("drm/i915: Disable
-Wuninitialized") because there were two warnings that were false
positives. The first was due to DECLARE_WAIT_QUEUE_HEAD_ONSTACK, which
was fixed in LLVM 9.0.0. The second was in busywait_stop, which was
fixed in LLVM 10.0.0 (issue 415). The kernel's minimum version for LLVM
is 10.0.1 so this warning can be safely enabled, where it has already
caught a couple bugs.

Link: ClangBuiltLinux#220
Link: ClangBuiltLinux#415
Link: ClangBuiltLinux#499
Link: llvm/llvm-project@2e04039
Link: llvm/llvm-project@c667cdc
Fixes: c562746 ("drm/i915: Disable -Wuninitialized")
References: 2ea4a7b ("drm/i915/gt: Avoid uninitialized use of rpcurupei in frequency_show")
References: 2034c21 ("drm/i915/display: Ensure that ret is always initialized in icl_combo_phy_verify_state")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
sys-oak pushed a commit to intel/linux-intel-lts that referenced this issue Mar 16, 2021
@nathanchance @ranjan-dutta
drm/i915: Enable -Wuninitialized
10d1ef0 
-Wunintialized was disabled in commit c562746 ("drm/i915: Disable
-Wuninitialized") because there were two warnings that were false
positives. The first was due to DECLARE_WAIT_QUEUE_HEAD_ONSTACK, which
was fixed in LLVM 9.0.0. The second was in busywait_stop, which was
fixed in LLVM 10.0.0 (issue 415). The kernel's minimum version for LLVM
is 10.0.1 so this warning can be safely enabled, where it has already
caught a couple bugs.

Link: ClangBuiltLinux/linux#220
Link: ClangBuiltLinux/linux#415
Link: ClangBuiltLinux/linux#499
Link: llvm/llvm-project@2e04039
Link: llvm/llvm-project@c667cdc
Fixes: c562746 ("drm/i915: Disable -Wuninitialized")
References: 2ea4a7b ("drm/i915/gt: Avoid uninitialized use of rpcurupei in frequency_show")
References: 2034c21 ("drm/i915/display: Ensure that ret is always initialized in icl_combo_phy_verify_state")
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20210216212953.24458-1-nathan@kernel.org
(cherry picked from commit b242318)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
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-Wuninitialized [ARCH] x86_64 This bug impacts ARCH=x86_64 [BUG] linux A bug that should be fixed in the mainline kernel. [FIXED][LINUX] 5.1 This bug was fixed in Linux 5.1
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