3d3d6b847420 ("kbuild: LLVMLinux: Adapt warnings for compilation with clang")

3d3d6b847420 ("kbuild: LLVMLinux: Adapt warnings for compilation with clang")

[Borislav Petkov]

Hi,

the commit in $Subject breaks the purpose of the W= build to see
additional warnings.

With it, currently I get all that stuff disabled with gcc:

$ make V=1 W=1  fs/direct-io.o

...

gcc -Wp,-MD,... -Wno-sign-compare -Wno-missing-field-initializers
-Wno-unused-value -Wno-format -Wno-sign-compare -Wno-format-zero-length
-Wno-uninitialized ...

which is clearly wrong. If I'm building with W=1, I *explicitly* *want*
those additional warnings enabled, not disabled.

Please fix this to have effect only for clang but not for the rest of
the universe.

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

Re: 3d3d6b847420 ("kbuild: LLVMLinux: Adapt warnings for compilation with clang")

[PaX Team]

On 16 Jun 2014 at 15:07, Borislav Petkov wrote:

> Please fix this to have effect only for clang but not for the rest of
> the universe.

i'd suggest reverting it instead, there're probably some stale entries
in there already (e.g., -fcatch-undefined-behavior).

Re: 3d3d6b847420 ("kbuild: LLVMLinux: Adapt warnings for compilation with clang")

[Jan-Simon Möller]

Ok, let's wrap this case with 

ifeq ($(COMPILER),clang)
...
endif

And we'll update the stale entries.

Patch to follow after some testing.

-- 

Dipl.-Ing.
Jan-Simon Möller

jansimon.moeller@gmx.de
Am Montag, 16. Juni 2014, 17:29:25 schrieb PaX Team:
> On 16 Jun 2014 at 15:07, Borislav Petkov wrote:
> > Please fix this to have effect only for clang but not for the rest of
> > the universe.
> 
> i'd suggest reverting it instead, there're probably some stale entries
> in there already (e.g., -fcatch-undefined-behavior).

Re: 3d3d6b847420 ("kbuild: LLVMLinux: Adapt warnings for compilation with clang")

[Borislav Petkov]

Hi,

On Mon, Jun 16, 2014 at 05:48:01PM +0200, Jan-Simon Möller wrote:
> Ok, let's wrap this case with 
> 
> ifeq ($(COMPILER),clang)
> ...
> endif
> 
> And we'll update the stale entries.
> 
> Patch to follow after some testing.

any progress with the testing or should we simply revert?

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

[PATCH] kbuild, LLVMLinux: only use warnings when using clang

[behanw]

From: Behan Webster <behanw@converseincode.com>

Only consider clang warnings in Kbuild when using the clang compiler.

Signed-off-by: Behan Webster <behanw@converseincode.com>
---
 scripts/Makefile.extrawarn | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 6564350..e350127 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -26,7 +26,7 @@ warning-1 += $(call cc-option, -Wmissing-include-dirs)
 warning-1 += $(call cc-option, -Wunused-but-set-variable)
 warning-1 += $(call cc-disable-warning, missing-field-initializers)
 
-# Clang
+ifeq ($(COMPILER),clang)
 warning-1 += $(call cc-disable-warning, initializer-overrides)
 warning-1 += $(call cc-disable-warning, unused-value)
 warning-1 += $(call cc-disable-warning, format)
@@ -35,6 +35,7 @@ warning-1 += $(call cc-disable-warning, sign-compare)
 warning-1 += $(call cc-disable-warning, format-zero-length)
 warning-1 += $(call cc-disable-warning, uninitialized)
 warning-1 += $(call cc-option, -fcatch-undefined-behavior)
+endif
 
 warning-2 := -Waggregate-return
 warning-2 += -Wcast-align
-- 
1.9.1

Re: [PATCH] kbuild, LLVMLinux: only use warnings when using clang

[Borislav Petkov]

On Mon, Jun 30, 2014 at 05:42:26PM -0700, behanw@converseincode.com wrote:
> From: Behan Webster <behanw@converseincode.com>
> 
> Only consider clang warnings in Kbuild when using the clang compiler.
> 
> Signed-off-by: Behan Webster <behanw@converseincode.com>
> ---
>  scripts/Makefile.extrawarn | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
> index 6564350..e350127 100644
> --- a/scripts/Makefile.extrawarn
> +++ b/scripts/Makefile.extrawarn
> @@ -26,7 +26,7 @@ warning-1 += $(call cc-option, -Wmissing-include-dirs)
>  warning-1 += $(call cc-option, -Wunused-but-set-variable)
>  warning-1 += $(call cc-disable-warning, missing-field-initializers)
>  
> -# Clang
> +ifeq ($(COMPILER),clang)
>  warning-1 += $(call cc-disable-warning, initializer-overrides)
>  warning-1 += $(call cc-disable-warning, unused-value)
>  warning-1 += $(call cc-disable-warning, format)
> @@ -35,6 +35,7 @@ warning-1 += $(call cc-disable-warning, sign-compare)
>  warning-1 += $(call cc-disable-warning, format-zero-length)
>  warning-1 += $(call cc-disable-warning, uninitialized)
>  warning-1 += $(call cc-option, -fcatch-undefined-behavior)
> +endif

Ok, just to make sure I understand that whole use case correctly:

The disabling of those warnings is really intended for the case where
people build the kernel with "W=1" on the make cmdline *and* clang?

Thanks.

-- 
Regards/Gruss,
    Boris.

Sent from a fat crate under my desk. Formatting is fine.
--

Re: [PATCH] kbuild, LLVMLinux: only use warnings when using clang

[Michal Marek]

On 2014-07-01 12:12, Borislav Petkov wrote:
> On Mon, Jun 30, 2014 at 05:42:26PM -0700, behanw@converseincode.com wrote:
>> From: Behan Webster <behanw@converseincode.com>
>>
>> Only consider clang warnings in Kbuild when using the clang compiler.
>>
>> Signed-off-by: Behan Webster <behanw@converseincode.com>
>> ---
>>  scripts/Makefile.extrawarn | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
>> index 6564350..e350127 100644
>> --- a/scripts/Makefile.extrawarn
>> +++ b/scripts/Makefile.extrawarn
>> @@ -26,7 +26,7 @@ warning-1 += $(call cc-option, -Wmissing-include-dirs)
>>  warning-1 += $(call cc-option, -Wunused-but-set-variable)
>>  warning-1 += $(call cc-disable-warning, missing-field-initializers)
>>  
>> -# Clang
>> +ifeq ($(COMPILER),clang)
>>  warning-1 += $(call cc-disable-warning, initializer-overrides)
>>  warning-1 += $(call cc-disable-warning, unused-value)
>>  warning-1 += $(call cc-disable-warning, format)
>> @@ -35,6 +35,7 @@ warning-1 += $(call cc-disable-warning, sign-compare)
>>  warning-1 += $(call cc-disable-warning, format-zero-length)
>>  warning-1 += $(call cc-disable-warning, uninitialized)
>>  warning-1 += $(call cc-option, -fcatch-undefined-behavior)
>> +endif
> 
> Ok, just to make sure I understand that whole use case correctly:
> 
> The disabling of those warnings is really intended for the case where
> people build the kernel with "W=1" on the make cmdline *and* clang?

Behan, Jan-Simon,

can you explain why are those -Wno-... options needed in the W=1 case?
The whole point of the W= option is to enable noisy warnings, so I don't
quite get why you want to silence these.

Thanks,
Michal

Re: [PATCH] kbuild, LLVMLinux: only use warnings when using clang

[Behan Webster]

On 07/30/14 06:04, Michal Marek wrote:
> On 2014-07-01 12:12, Borislav Petkov wrote:
>> On Mon, Jun 30, 2014 at 05:42:26PM -0700, behanw@converseincode.com wrote:
>>> From: Behan Webster <behanw@converseincode.com>
>>>
>>> Only consider clang warnings in Kbuild when using the clang compiler.
>>>
>>> Signed-off-by: Behan Webster <behanw@converseincode.com>
>>> ---
>>>   scripts/Makefile.extrawarn | 3 ++-
>>>   1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
>>> index 6564350..e350127 100644
>>> --- a/scripts/Makefile.extrawarn
>>> +++ b/scripts/Makefile.extrawarn
>>> @@ -26,7 +26,7 @@ warning-1 += $(call cc-option, -Wmissing-include-dirs)
>>>   warning-1 += $(call cc-option, -Wunused-but-set-variable)
>>>   warning-1 += $(call cc-disable-warning, missing-field-initializers)
>>>   
>>> -# Clang
>>> +ifeq ($(COMPILER),clang)
>>>   warning-1 += $(call cc-disable-warning, initializer-overrides)
>>>   warning-1 += $(call cc-disable-warning, unused-value)
>>>   warning-1 += $(call cc-disable-warning, format)
>>> @@ -35,6 +35,7 @@ warning-1 += $(call cc-disable-warning, sign-compare)
>>>   warning-1 += $(call cc-disable-warning, format-zero-length)
>>>   warning-1 += $(call cc-disable-warning, uninitialized)
>>>   warning-1 += $(call cc-option, -fcatch-undefined-behavior)
>>> +endif
>> Ok, just to make sure I understand that whole use case correctly:
>>
>> The disabling of those warnings is really intended for the case where
>> people build the kernel with "W=1" on the make cmdline *and* clang?
> Behan, Jan-Simon,
>
> can you explain why are those -Wno-... options needed in the W=1 case?
> The whole point of the W= option is to enable noisy warnings, so I don't
> quite get why you want to silence these.
Sorry for the delay.

That code is indeed not what was intended. It's more that these warnings 
should normally be disabled, and when W is set they should not be disabled.

Just putting the final touches on a patch which addresses this situation.

Behan

-- 
Behan Webster
behanw@converseincode.com

[PATCH v2] kbuild, LLVMLinux: Supress warnings unless W=1-3

[behanw]

From: Behan Webster <behanw@converseincode.com>

clang has more warnings enabled by default. Turn them off unless W is set.
This patch fixes a logic bug where warnings in clang were disabled when W was set.

Signed-off-by: Behan Webster <behanw@converseincode.com>
Signed-off-by: Jan-Simon Möller <dl9pf@gmx.de>
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
Cc: mmarek@suse.cz
Cc: bp@alien8.de
---
 Makefile                   |  1 +
 scripts/Makefile.extrawarn | 22 ++++++++++++----------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/Makefile b/Makefile
index f6a7794..f343e17 100644
--- a/Makefile
+++ b/Makefile
@@ -668,6 +668,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
 # source of a reference will be _MergedGlobals and not on of the whitelisted names.
 # See modpost pattern 2
 KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
+KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
 else
 
 # This warning generated too much noise in a regular build.
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 6564350..b5b0751 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -26,16 +26,6 @@ warning-1 += $(call cc-option, -Wmissing-include-dirs)
 warning-1 += $(call cc-option, -Wunused-but-set-variable)
 warning-1 += $(call cc-disable-warning, missing-field-initializers)
 
-# Clang
-warning-1 += $(call cc-disable-warning, initializer-overrides)
-warning-1 += $(call cc-disable-warning, unused-value)
-warning-1 += $(call cc-disable-warning, format)
-warning-1 += $(call cc-disable-warning, unknown-warning-option)
-warning-1 += $(call cc-disable-warning, sign-compare)
-warning-1 += $(call cc-disable-warning, format-zero-length)
-warning-1 += $(call cc-disable-warning, uninitialized)
-warning-1 += $(call cc-option, -fcatch-undefined-behavior)
-
 warning-2 := -Waggregate-return
 warning-2 += -Wcast-align
 warning-2 += -Wdisabled-optimization
@@ -55,6 +45,18 @@ warning-3 += -Wswitch-default
 warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
 warning-3 += $(call cc-option, -Wvla)
 
+ifeq ($(COMPILER),clang)
+ifndef $(W)
+KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
+KBUILD_CFLAGS += $(call cc-disable-warning, format)
+KBUILD_CFLAGS += $(call cc-disable-warning, unknown-warning-option)
+KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
+KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
+KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
+endif
+endif
+
 warning := $(warning-$(findstring 1, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
 warning += $(warning-$(findstring 2, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
 warning += $(warning-$(findstring 3, $(KBUILD_ENABLE_EXTRA_GCC_CHECKS)))
-- 
1.9.1

Re: [PATCH v2] kbuild, LLVMLinux: Supress warnings unless W=1-3

[Michal Marek]

Dne 31.7.2014 06:16, behanw@converseincode.com napsal(a):
> From: Behan Webster <behanw@converseincode.com>
> 
> clang has more warnings enabled by default. Turn them off unless W is set.
> This patch fixes a logic bug where warnings in clang were disabled when W was set.
> 
> Signed-off-by: Behan Webster <behanw@converseincode.com>
> Signed-off-by: Jan-Simon Möller <dl9pf@gmx.de>
> Signed-off-by: Mark Charlebois <charlebm@gmail.com>
> Cc: mmarek@suse.cz
> Cc: bp@alien8.de
> ---
>  Makefile                   |  1 +
>  scripts/Makefile.extrawarn | 22 ++++++++++++----------
>  2 files changed, 13 insertions(+), 10 deletions(-)
> 
> diff --git a/Makefile b/Makefile
> index f6a7794..f343e17 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -668,6 +668,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
>  # source of a reference will be _MergedGlobals and not on of the whitelisted names.
>  # See modpost pattern 2
>  KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
> +KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
>  else
>  
>  # This warning generated too much noise in a regular build.
> diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
> index 6564350..b5b0751 100644
> --- a/scripts/Makefile.extrawarn
> +++ b/scripts/Makefile.extrawarn
> @@ -26,16 +26,6 @@ warning-1 += $(call cc-option, -Wmissing-include-dirs)
>  warning-1 += $(call cc-option, -Wunused-but-set-variable)
>  warning-1 += $(call cc-disable-warning, missing-field-initializers)
>  
> -# Clang
> -warning-1 += $(call cc-disable-warning, initializer-overrides)
> -warning-1 += $(call cc-disable-warning, unused-value)
> -warning-1 += $(call cc-disable-warning, format)
> -warning-1 += $(call cc-disable-warning, unknown-warning-option)
> -warning-1 += $(call cc-disable-warning, sign-compare)
> -warning-1 += $(call cc-disable-warning, format-zero-length)
> -warning-1 += $(call cc-disable-warning, uninitialized)
> -warning-1 += $(call cc-option, -fcatch-undefined-behavior)
> -

OK.


>  warning-2 := -Waggregate-return
>  warning-2 += -Wcast-align
>  warning-2 += -Wdisabled-optimization
> @@ -55,6 +45,18 @@ warning-3 += -Wswitch-default
>  warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
>  warning-3 += $(call cc-option, -Wvla)
>  
> +ifeq ($(COMPILER),clang)
> +ifndef $(W)
> +KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
> +KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
> +KBUILD_CFLAGS += $(call cc-disable-warning, format)
> +KBUILD_CFLAGS += $(call cc-disable-warning, unknown-warning-option)
> +KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
> +KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
> +KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
> +endif
> +endif
> +

Please remove this part, it has no effect. I assume that if it works for
you, these warning are not as annoying so they do not need to be disabled?

Thanks,
Michal

Re: [PATCH v2] kbuild, LLVMLinux: Supress warnings unless W=1-3

[Behan Webster]

On 07/31/14 01:18, Michal Marek wrote:
> Dne 31.7.2014 06:16, behanw@converseincode.com napsal(a):
>> From: Behan Webster <behanw@converseincode.com>
>>
>> clang has more warnings enabled by default. Turn them off unless W is set.
>> This patch fixes a logic bug where warnings in clang were disabled when W was set.
>>
>> Signed-off-by: Behan Webster <behanw@converseincode.com>
>> Signed-off-by: Jan-Simon Möller <dl9pf@gmx.de>
>> Signed-off-by: Mark Charlebois <charlebm@gmail.com>
>> Cc: mmarek@suse.cz
>> Cc: bp@alien8.de
>> ---
>>   Makefile                   |  1 +
>>   scripts/Makefile.extrawarn | 22 ++++++++++++----------
>>   2 files changed, 13 insertions(+), 10 deletions(-)
>>
>> diff --git a/Makefile b/Makefile
>> index f6a7794..f343e17 100644
>> --- a/Makefile
>> +++ b/Makefile
>> @@ -668,6 +668,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
>>   # source of a reference will be _MergedGlobals and not on of the whitelisted names.
>>   # See modpost pattern 2
>>   KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
>> +KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
>>   else
>>   
>>   # This warning generated too much noise in a regular build.
>> diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
>> index 6564350..b5b0751 100644
>> --- a/scripts/Makefile.extrawarn
>> +++ b/scripts/Makefile.extrawarn
>> @@ -26,16 +26,6 @@ warning-1 += $(call cc-option, -Wmissing-include-dirs)
>>   warning-1 += $(call cc-option, -Wunused-but-set-variable)
>>   warning-1 += $(call cc-disable-warning, missing-field-initializers)
>>   
>> -# Clang
>> -warning-1 += $(call cc-disable-warning, initializer-overrides)
>> -warning-1 += $(call cc-disable-warning, unused-value)
>> -warning-1 += $(call cc-disable-warning, format)
>> -warning-1 += $(call cc-disable-warning, unknown-warning-option)
>> -warning-1 += $(call cc-disable-warning, sign-compare)
>> -warning-1 += $(call cc-disable-warning, format-zero-length)
>> -warning-1 += $(call cc-disable-warning, uninitialized)
>> -warning-1 += $(call cc-option, -fcatch-undefined-behavior)
>> -
> OK.
>
>
>>   warning-2 := -Waggregate-return
>>   warning-2 += -Wcast-align
>>   warning-2 += -Wdisabled-optimization
>> @@ -55,6 +45,18 @@ warning-3 += -Wswitch-default
>>   warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
>>   warning-3 += $(call cc-option, -Wvla)
>>   
>> +ifeq ($(COMPILER),clang)
>> +ifndef $(W)
>> +KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
>> +KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
>> +KBUILD_CFLAGS += $(call cc-disable-warning, format)
>> +KBUILD_CFLAGS += $(call cc-disable-warning, unknown-warning-option)
>> +KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
>> +KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
>> +KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
>> +endif
>> +endif
>> +
> Please remove this part, it has no effect. I assume that if it works for
> you, these warning are not as annoying so they do not need to be disabled?
Actually they are annoying, that's why they're disabled normally. Most 
of them complain about practices which are relatively common in kernel code.

clang warns about a lot more things than gcc does. It means that code 
which compiles cleanly in gcc often doesn't with clang. This cuts out 
the warnings which are unlikely to to be fixed in kernel code anytime 
soon, but which are probably worth exposing when W=1 is used.

This part of the patch explicitly deals with complaints from some in the 
kernel community that clang is too noisy with kernel code.

This part of the patch needs to be somewhere. This seemed the best place.

Behan

-- 
Behan Webster
behanw@converseincode.com

Re: [PATCH v2] kbuild, LLVMLinux: Supress warnings unless W=1-3

[Michal Marek]

Dne 31.7.2014 18:12, Behan Webster napsal(a):
> On 07/31/14 01:18, Michal Marek wrote:
>> Dne 31.7.2014 06:16, behanw@converseincode.com napsal(a):
>>> @@ -55,6 +45,18 @@ warning-3 += -Wswitch-default
>>>   warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
>>>   warning-3 += $(call cc-option, -Wvla)
>>>   +ifeq ($(COMPILER),clang)
>>> +ifndef $(W)
>>> +KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
>>> +KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
>>> +KBUILD_CFLAGS += $(call cc-disable-warning, format)
>>> +KBUILD_CFLAGS += $(call cc-disable-warning, unknown-warning-option)
>>> +KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
>>> +KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
>>> +KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
>>> +endif
>>> +endif
>>> +
>> Please remove this part, it has no effect. I assume that if it works for
>> you, these warning are not as annoying so they do not need to be
>> disabled?
> Actually they are annoying, that's why they're disabled normally. Most
> of them complain about practices which are relatively common in kernel
> code.
> 
> clang warns about a lot more things than gcc does. It means that code
> which compiles cleanly in gcc often doesn't with clang. This cuts out
> the warnings which are unlikely to to be fixed in kernel code anytime
> soon, but which are probably worth exposing when W=1 is used.
> 
> This part of the patch explicitly deals with complaints from some in the
> kernel community that clang is too noisy with kernel code.
> 
> This part of the patch needs to be somewhere. This seemed the best place.

You placed it inside a branch that is only evaluated when W= is given.

Michal

Re: [PATCH v2] kbuild, LLVMLinux: Supress warnings unless W=1-3

[Behan Webster]

On 07/31/14 13:46, Michal Marek wrote:
> Dne 31.7.2014 18:12, Behan Webster napsal(a):
>> On 07/31/14 01:18, Michal Marek wrote:
>>> Dne 31.7.2014 06:16, behanw@converseincode.com napsal(a):
>>>> @@ -55,6 +45,18 @@ warning-3 += -Wswitch-default
>>>>    warning-3 += $(call cc-option, -Wpacked-bitfield-compat)
>>>>    warning-3 += $(call cc-option, -Wvla)
>>>>    +ifeq ($(COMPILER),clang)
>>>> +ifndef $(W)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, format)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, unknown-warning-option)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
>>>> +KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
>>>> +endif
>>>> +endif
>>>> +
>>> Please remove this part, it has no effect. I assume that if it works for
>>> you, these warning are not as annoying so they do not need to be
>>> disabled?
>> Actually they are annoying, that's why they're disabled normally. Most
>> of them complain about practices which are relatively common in kernel
>> code.
>>
>> clang warns about a lot more things than gcc does. It means that code
>> which compiles cleanly in gcc often doesn't with clang. This cuts out
>> the warnings which are unlikely to to be fixed in kernel code anytime
>> soon, but which are probably worth exposing when W=1 is used.
>>
>> This part of the patch explicitly deals with complaints from some in the
>> kernel community that clang is too noisy with kernel code.
>>
>> This part of the patch needs to be somewhere. This seemed the best place.
> You placed it inside a branch that is only evaluated when W= is given.
Hmm. You're right. Will fix.

Behan

-- 
Behan Webster
behanw@converseincode.com

[PATCH v3] kbuild, LLVMLinux: Supress warnings unless W=1-3

[behanw]

From: Behan Webster <behanw@converseincode.com>

clang has more warnings enabled by default. Turn them off unless W is set.
This patch fixes a logic bug where warnings in clang were disabled when W was set.

Signed-off-by: Behan Webster <behanw@converseincode.com>
Signed-off-by: Jan-Simon Möller <dl9pf@gmx.de>
Signed-off-by: Mark Charlebois <charlebm@gmail.com>
Cc: mmarek@suse.cz
Cc: bp@alien8.de
---
 Makefile                   |  1 +
 scripts/Makefile.extrawarn | 22 ++++++++++++----------
 2 files changed, 13 insertions(+), 10 deletions(-)

diff --git a/Makefile b/Makefile
index f6a7794..f343e17 100644
--- a/Makefile
+++ b/Makefile
@@ -668,6 +668,7 @@ KBUILD_CFLAGS += $(call cc-disable-warning, tautological-compare)
 # source of a reference will be _MergedGlobals and not on of the whitelisted names.
 # See modpost pattern 2
 KBUILD_CFLAGS += $(call cc-option, -mno-global-merge,)
+KBUILD_CFLAGS += $(call cc-option, -fcatch-undefined-behavior)
 else
 
 # This warning generated too much noise in a regular build.
diff --git a/scripts/Makefile.extrawarn b/scripts/Makefile.extrawarn
index 6564350..4315d34 100644
--- a/scripts/Makefile.extrawarn
+++ b/scripts/Makefile.extrawarn
@@ -26,16 +26,6 @@ warning-1 += $(call cc-option, -Wmissing-include-dirs)
 warning-1 += $(call cc-option, -Wunused-but-set-variable)
 warning-1 += $(call cc-disable-warning, missing-field-initializers)
 
-# Clang
-warning-1 += $(call cc-disable-warning, initializer-overrides)
-warning-1 += $(call cc-disable-warning, unused-value)
-warning-1 += $(call cc-disable-warning, format)
-warning-1 += $(call cc-disable-warning, unknown-warning-option)
-warning-1 += $(call cc-disable-warning, sign-compare)
-warning-1 += $(call cc-disable-warning, format-zero-length)
-warning-1 += $(call cc-disable-warning, uninitialized)
-warning-1 += $(call cc-option, -fcatch-undefined-behavior)
-
 warning-2 := -Waggregate-return
 warning-2 += -Wcast-align
 warning-2 += -Wdisabled-optimization
@@ -64,4 +54,16 @@ ifeq ("$(strip $(warning))","")
 endif
 
 KBUILD_CFLAGS += $(warning)
+else
+
+ifeq ($(COMPILER),clang)
+KBUILD_CFLAGS += $(call cc-disable-warning, initializer-overrides)
+KBUILD_CFLAGS += $(call cc-disable-warning, unused-value)
+KBUILD_CFLAGS += $(call cc-disable-warning, format)
+KBUILD_CFLAGS += $(call cc-disable-warning, unknown-warning-option)
+KBUILD_CFLAGS += $(call cc-disable-warning, sign-compare)
+KBUILD_CFLAGS += $(call cc-disable-warning, format-zero-length)
+KBUILD_CFLAGS += $(call cc-disable-warning, uninitialized)
 endif
+endif
+
-- 
1.9.1

Re: [PATCH v3] kbuild, LLVMLinux: Supress warnings unless W=1-3

[Michal Marek]

On 2014-08-01 06:08, behanw@converseincode.com wrote:
> From: Behan Webster <behanw@converseincode.com>
> 
> clang has more warnings enabled by default. Turn them off unless W is set.
> This patch fixes a logic bug where warnings in clang were disabled when W was set.
> 
> Signed-off-by: Behan Webster <behanw@converseincode.com>
> Signed-off-by: Jan-Simon Möller <dl9pf@gmx.de>
> Signed-off-by: Mark Charlebois <charlebm@gmail.com>
> Cc: mmarek@suse.cz
> Cc: bp@alien8.de
> ---
>  Makefile                   |  1 +
>  scripts/Makefile.extrawarn | 22 ++++++++++++----------
>  2 files changed, 13 insertions(+), 10 deletions(-)

OK, this looks better, I applied the patch to kbuild.git#kbuild.


> +KBUILD_CFLAGS += $(call cc-disable-warning, unknown-warning-option)

Do we have -W... options in the Makefiles that clang does not understand
and that are added unconditionally?

Thanks,
Michal