linux-kernel - Re: linux-next: manual merge of the compiler-attributes tree with the kbuild tree

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Date:   Tue, 30 Oct 2018 15:04:13 +0000
From:   Changbin Du <changbin.du@...il.com>
To:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>
Cc:     Stephen Rothwell <sfr@...b.auug.org.au>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Linux-Next Mailing List <linux-next@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        changbin.du@...il.com
Subject: Re: linux-next: manual merge of the compiler-attributes tree with
 the kbuild tree

On Tue, Oct 30, 2018 at 12:21:52PM +0100, Miguel Ojeda wrote:
> On Tue, Oct 30, 2018 at 12:49 AM Stephen Rothwell <sfr@...b.auug.org.au> wrote:
> >
> > Hi all,
> >
> > On Tue, 30 Oct 2018 10:46:37 +1100 Stephen Rothwell <sfr@...b.auug.org.au> wrote:
> > >
> > > Today's linux-next merge of the compiler-attributes tree got a conflict
> > > in:
> > >
> > >   include/linux/compiler-gcc.h
> > >
> > > between commit:
> > >
> > >   94c7dfd01652 ("kernel hacking: support building kernel with -Og optimization level")
> > >
> > > from the kbuild tree and commits:
> > >
> > >   5c67a52f3da0 ("Compiler Attributes: always use the extra-underscores syntax")
> > >   989bd5000f36 ("Compiler Attributes: remove unneeded sparse (__CHECKER__) tests")
> > >
> > > from the compiler-attributes tree.
> > >
> > > I fixed it up (the latter just removed the __CHECKER__ check, so I did
> > > that) and can carry the fix as necessary. This is now fixed as far as
> >
> > On reflection, that may not have been the correct resolution ...
> 
> From a quick look, it seems we want:
> 
> #ifndef CONFIG_CC_OPTIMIZE_FOR_DEBUGGING
> #define __compiletime_warning(message) __attribute__((__warning__(message)))
> #define __compiletime_error(message) __attribute__((__error__(message)))
> #endif
> 
> i.e. kbuild tree added the CONFIG_CC_OPTIMIZE_FOR_DEBUGGING guard,
> while the compiler-attributes tree removed the __CHECKER__ one, so we
> still need the former.
> 
> By the way, I think 94c7dfd01652 is wrong: it changes the guard also
> for __latent_entropy (and it does not change the corresponding comment
> at "#endif /* __CHECKER__ */").
> 
> Also, the commit message does not mention __compiletime_warning --
> should that one be guarded too by CONFIG_CC_OPTIMIZE_FOR_DEBUGGING?
> 
To avoid future possible warning, __compiletime_warning should also be
guarded. So I did the flow change so __latent_entropy is not affected.

--- a/include/linux/compiler-gcc.h
+++ b/include/linux/compiler-gcc.h
@@ -85,9 +85,11 @@
 
 #define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
 
-#if !defined(__CHECKER__) && !defined(CONFIG_CC_OPTIMIZE_FOR_DEBUGGING)
+#if !defined(__CHECKER__)
+#if !defined(CONFIG_CC_OPTIMIZE_FOR_DEBUGGING)
 #define __compiletime_warning(message) __attribute__((warning(message)))
 #define __compiletime_error(message) __attribute__((error(message)))
+#endif
 
 #ifdef LATENT_ENTROPY_PLUGIN
 #define __latent_entropy __attribute__((latent_entropy))


> Cheers,
> Miguel

-- 
Thanks,
Changbin Du