diff mbox

Fix sh4 build with __ASSUME_ST_INO_64_BIT redefinition

Message ID 1478695312-5009-1-git-send-email-adhemerval.zanella@linaro.org
State Accepted
Commit 0a557c105cad94758543e18b4834c15da2c39eb8
Headers show

Commit Message

Adhemerval Zanella Netto Nov. 9, 2016, 12:41 p.m. UTC
Since 327792c sh4 builds fails with:

../sysdeps/unix/sysv/linux/kernel-features.h:49:0: error: "__ASSUME_ST_INO_64_BIT" redefined [-Werror]
 #define __ASSUME_ST_INO_64_BIT  1
 ^
In file included from ../sysdeps/unix/sysv/linux/sysdep.h:19:0,
                 from ../sysdeps/unix/sysv/linux/sh/sysdep.h:24,
                 from ../sysdeps/unix/sysv/linux/sh/sh4/sysdep.h:4,
                 from <stdin>:1:
../sysdeps/unix/sysv/linux/sh/kernel-features.h:47:0: note: this is the location of the previous definition
 #define __ASSUME_ST_INO_64_BIT 0

It is because sh4 kernel-features.sh is included multiple times
without guards and this patch fixes by adding them. Tested on a
sh4-linux-gnu build.

Also with this issues, is there are strong reason to *not* have include guards
on kernel-features.h?  With current approach, a architecture can't include
Linux default kernel-features.h and redefine it to a different value, only
undefine it (unless it explicit do not include default kernel-features.h,
and I think that's is not the idea).

	* sysdeps/unix/sysv/linux/sh/kernel-features.h: Add include
	guards.
---
 ChangeLog                                    | 5 +++++
 sysdeps/unix/sysv/linux/sh/kernel-features.h | 5 +++++
 2 files changed, 10 insertions(+)

-- 
2.7.4

Comments

Joseph Myers Nov. 10, 2016, 6:07 p.m. UTC | #1
On Wed, 9 Nov 2016, Adhemerval Zanella wrote:

> It is because sh4 kernel-features.sh is included multiple times

> without guards and this patch fixes by adding them. Tested on a

> sh4-linux-gnu build.

> 

> Also with this issues, is there are strong reason to *not* have include guards

> on kernel-features.h?  With current approach, a architecture can't include

> Linux default kernel-features.h and redefine it to a different value, only

> undefine it (unless it explicit do not include default kernel-features.h,

> and I think that's is not the idea).

> 

> 	* sysdeps/unix/sysv/linux/sh/kernel-features.h: Add include

> 	guards.


OK.  I think it's appropriate for all these headers to have include 
guards.

The #ifndef, #undef etc. could be avoided (moving this header closer to 
glibc's macro-name-typo-proof norms in this regard) if the header were 
split up into smaller pieces for individual macros or groups of related 
macros whenever a macro's definition needs to vary between architectures.  
Thus, you'd have e.g. kernel-features-st-ino.h defining 
__ASSUME_ST_INO_64_BIT to either 0 or 1, the default version of that 
header would define to 0 and the architectures overriding it would define 
to 1 (and wouldn't need #include_next).  kernel-features.h could end up as 
an architecture-independent header that just #includes the smaller 
architecture-specific headers.  (This is not a full design, especially for 
the more complicated cases such as socket syscalls.)

-- 
Joseph S. Myers
joseph@codesourcery.com
Adhemerval Zanella Netto Nov. 10, 2016, 8:02 p.m. UTC | #2
On 10/11/2016 16:07, Joseph Myers wrote:
> On Wed, 9 Nov 2016, Adhemerval Zanella wrote:

> 

>> It is because sh4 kernel-features.sh is included multiple times

>> without guards and this patch fixes by adding them. Tested on a

>> sh4-linux-gnu build.

>>

>> Also with this issues, is there are strong reason to *not* have include guards

>> on kernel-features.h?  With current approach, a architecture can't include

>> Linux default kernel-features.h and redefine it to a different value, only

>> undefine it (unless it explicit do not include default kernel-features.h,

>> and I think that's is not the idea).

>>

>> 	* sysdeps/unix/sysv/linux/sh/kernel-features.h: Add include

>> 	guards.

> 

> OK.  I think it's appropriate for all these headers to have include 

> guards.


Ok, I will push this patch.

> 

> The #ifndef, #undef etc. could be avoided (moving this header closer to 

> glibc's macro-name-typo-proof norms in this regard) if the header were 

> split up into smaller pieces for individual macros or groups of related 

> macros whenever a macro's definition needs to vary between architectures.  

> Thus, you'd have e.g. kernel-features-st-ino.h defining 

> __ASSUME_ST_INO_64_BIT to either 0 or 1, the default version of that 

> header would define to 0 and the architectures overriding it would define 

> to 1 (and wouldn't need #include_next).  kernel-features.h could end up as 

> an architecture-independent header that just #includes the smaller 

> architecture-specific headers.  (This is not a full design, especially for 

> the more complicated cases such as socket syscalls.)


This could be a feasible approach, although it would require some extensive
refactoring.  But I think we current approach, where architecture 
kernel-feature is used from sysdep and it is responsible to include default
linux one and undef and redefine value, plus guards should be also feasible
for macro-name-typo-proof as well.
diff mbox

Patch

diff --git a/sysdeps/unix/sysv/linux/sh/kernel-features.h b/sysdeps/unix/sysv/linux/sh/kernel-features.h
index ea4fdbc..d03aafa 100644
--- a/sysdeps/unix/sysv/linux/sh/kernel-features.h
+++ b/sysdeps/unix/sysv/linux/sh/kernel-features.h
@@ -17,6 +17,9 @@ 
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
+#ifndef __KERNEL_FEATURES_SH__
+# define __KERNEL_FEATURES_SH__
+
 /* SH uses socketcall.  */
 #define __ASSUME_SOCKETCALL		1
 
@@ -50,3 +53,5 @@ 
    the kernel interface for p{read,write}64 adds a dummy long argument
    before the offset.  */
 #define __ASSUME_PRW_DUMMY_ARG	1
+
+#endif