[PATCH] netfilter: conntrack: Force inlining of build check to prevent build failure

[PATCH] netfilter: conntrack: Force inlining of build check to prevent build failure

[Geert Uytterhoeven]

If gcc (e.g. 4.1.2) decides not to inline total_extension_size(), the
build will fail with:

    net/built-in.o: In function `nf_conntrack_init_start':
    (.text+0x9baf6): undefined reference to `__compiletime_assert_1893'

or

    ERROR: "__compiletime_assert_1893" [net/netfilter/nf_conntrack.ko] undefined!

Fix this by forcing inlining of total_extension_size().

Fixes: b3a5db109e0670d6 ("netfilter: conntrack: use u8 for extension sizes again")
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---
 net/netfilter/nf_conntrack_core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index f9245dbfe4356da6..3c8f1ed2f5558fe0 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -1853,7 +1853,7 @@ EXPORT_SYMBOL_GPL(nf_conntrack_set_hashsize);
 module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
 		  &nf_conntrack_htable_size, 0600);
 
-static unsigned int total_extension_size(void)
+static __always_inline unsigned int total_extension_size(void)
 {
 	/* remember to add new extensions below */
 	BUILD_BUG_ON(NF_CT_EXT_NUM > 9);
-- 
2.7.4

Re: [PATCH] netfilter: conntrack: Force inlining of build check to prevent build failure

[Arnd Bergmann]

On Wed, May 3, 2017 at 2:18 PM, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> If gcc (e.g. 4.1.2) decides not to inline total_extension_size(), the
> build will fail with:
>
>     net/built-in.o: In function `nf_conntrack_init_start':
>     (.text+0x9baf6): undefined reference to `__compiletime_assert_1893'
>
> or
>
>     ERROR: "__compiletime_assert_1893" [net/netfilter/nf_conntrack.ko] undefined!
>
> Fix this by forcing inlining of total_extension_size().
>
> Fixes: b3a5db109e0670d6 ("netfilter: conntrack: use u8 for extension sizes again")
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

I saw this as well when I tried building with "gcc-7 -Og", and came to the same
conclusion.

Acked-by: Arnd Bergmann <arnd@arndb.de>

With -Og, there were a couple of other instances of BUILD_BUG_ON() failing
to see a compile-time constant, presumably as it fails to inline any functions
that are not explicitly marked inline.

       Arnd

Re: [PATCH] netfilter: conntrack: Force inlining of build check to prevent build failure

[Geert Uytterhoeven]

Hi Arnd,

On Wed, May 3, 2017 at 2:32 PM, Arnd Bergmann <arnd@arndb.de> wrote:
> On Wed, May 3, 2017 at 2:18 PM, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>> If gcc (e.g. 4.1.2) decides not to inline total_extension_size(), the
>> build will fail with:
>>
>>     net/built-in.o: In function `nf_conntrack_init_start':
>>     (.text+0x9baf6): undefined reference to `__compiletime_assert_1893'
>>
>> or
>>
>>     ERROR: "__compiletime_assert_1893" [net/netfilter/nf_conntrack.ko] undefined!
>>
>> Fix this by forcing inlining of total_extension_size().
>>
>> Fixes: b3a5db109e0670d6 ("netfilter: conntrack: use u8 for extension sizes again")
>> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
>
> I saw this as well when I tried building with "gcc-7 -Og", and came to the same
> conclusion.

Good^H^H^H^HBad to see it not only happens with ancient compilers ;-)

> Acked-by: Arnd Bergmann <arnd@arndb.de>

Thanks!

Gr{oetje,eeting}s,

                        Geert

Re: [PATCH] netfilter: conntrack: Force inlining of build check to prevent build failure

[Arnd Bergmann]

On Wed, May 3, 2017 at 2:47 PM, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> Hi Arnd,
>
> On Wed, May 3, 2017 at 2:32 PM, Arnd Bergmann <arnd@arndb.de> wrote:
>> On Wed, May 3, 2017 at 2:18 PM, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>>> If gcc (e.g. 4.1.2) decides not to inline total_extension_size(), the
>>> build will fail with:
>>>
>>>     net/built-in.o: In function `nf_conntrack_init_start':
>>>     (.text+0x9baf6): undefined reference to `__compiletime_assert_1893'
>>>
>>> or
>>>
>>>     ERROR: "__compiletime_assert_1893" [net/netfilter/nf_conntrack.ko] undefined!
>>>
>>> Fix this by forcing inlining of total_extension_size().
>>>
>>> Fixes: b3a5db109e0670d6 ("netfilter: conntrack: use u8 for extension sizes again")
>>> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
>>
>> I saw this as well when I tried building with "gcc-7 -Og", and came to the same
>> conclusion.
>
> Good^H^H^H^HBad to see it not only happens with ancient compilers ;-)

Right now we don't see it on newer compilers (I assume gcc-4.3 or up) as we
always build with either -O2 or -Os optimizations. I was playing with -Og the
other day to get faster builds, but that causes many build failures
and additional
warnings as the result of missing out on optimizations that we have come
to rely on.

It might be worth getting -Og to build if the compile time is
drastically faster, but
we probably have to completely do away with BUILD_BUG_ON() and similar
checks in that configuration, which in turn makes the build output less
valuable.

       Arnd

Re: [PATCH] netfilter: conntrack: Force inlining of build check to prevent build failure

[Florian Westphal]

Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> If gcc (e.g. 4.1.2) decides not to inline total_extension_size(), the
> build will fail with:
> 
>     net/built-in.o: In function `nf_conntrack_init_start':
>     (.text+0x9baf6): undefined reference to `__compiletime_assert_1893'
> 
> or
> 
>     ERROR: "__compiletime_assert_1893" [net/netfilter/nf_conntrack.ko] undefined!
> 
> Fix this by forcing inlining of total_extension_size().

Sorry about that, thanks for the fix Geert.

Acked-by: Florian Westphal <fw@strlen.de>

Re: [PATCH] netfilter: conntrack: Force inlining of build check to prevent build failure

[David Miller]

From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: Wed,  3 May 2017 14:18:43 +0200

> If gcc (e.g. 4.1.2) decides not to inline total_extension_size(), the
> build will fail with:
> 
>     net/built-in.o: In function `nf_conntrack_init_start':
>     (.text+0x9baf6): undefined reference to `__compiletime_assert_1893'
> 
> or
> 
>     ERROR: "__compiletime_assert_1893" [net/netfilter/nf_conntrack.ko] undefined!
> 
> Fix this by forcing inlining of total_extension_size().
> 
> Fixes: b3a5db109e0670d6 ("netfilter: conntrack: use u8 for extension sizes again")
> Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

Pablo, I'm going to apply this directly to my tree to fix this build
failure, I hope you don't mind.

Thanks.

Re: [PATCH] netfilter: conntrack: Force inlining of build check to prevent build failure

[Pablo Neira Ayuso]

On Wed, May 03, 2017 at 09:55:16AM -0400, David Miller wrote:
> From: Geert Uytterhoeven <geert@linux-m68k.org>
> Date: Wed,  3 May 2017 14:18:43 +0200
> 
> > If gcc (e.g. 4.1.2) decides not to inline total_extension_size(), the
> > build will fail with:
> > 
> >     net/built-in.o: In function `nf_conntrack_init_start':
> >     (.text+0x9baf6): undefined reference to `__compiletime_assert_1893'
> > 
> > or
> > 
> >     ERROR: "__compiletime_assert_1893" [net/netfilter/nf_conntrack.ko] undefined!
> > 
> > Fix this by forcing inlining of total_extension_size().
> > 
> > Fixes: b3a5db109e0670d6 ("netfilter: conntrack: use u8 for extension sizes again")
> > Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
> 
> Pablo, I'm going to apply this directly to my tree to fix this build
> failure, I hope you don't mind.

Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>