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    SubjectRe: [next:akpm 129/309] net/core/sock.c:274:36: error: initializer element is not constant
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    On 23-Jul-12, at 8:29 AM, Fengguang Wu wrote:

    > On Mon, Jul 23, 2012 at 12:42:58PM +0100, Mel Gorman wrote:
    >> On Mon, Jul 23, 2012 at 12:20:20PM +0100, James Bottomley wrote:
    >>> [Parisc list cc added]
    >>> On Mon, 2012-07-23 at 12:16 +0100, Mel Gorman wrote:
    >>>> On Mon, Jul 23, 2012 at 12:30:58AM +0800, Fengguang Wu wrote:
    >>>>> Hi Mel,
    >>>>>
    >>>>> To be frank, I don't quite understand this build failure..
    >>>>>
    >>>>> tree: next/akpm akpm
    >>>>> head: 37e2ad4953983527f7bdb6831bf478eedcc84082
    >>>>> commit: 799dc3a908b1df8b766c35aefc24c1b5356aa051 [129/309]
    >>>>> netvm: allow skb allocation to use PFMEMALLOC reserves
    >>>>> config: parisc-defconfig (attached as .config)
    >>>>>
    >>>>> All related error/warning messages:
    >>>>>
    >>>>> net/core/sock.c:274:36: error: initializer element is not constant
    >>>>> net/core/sock.c:274:36: error: (near initialization for
    >>>>> 'memalloc_socks')
    >>>>> net/core/sock.c:274:36: error: initializer element is not constant
    >>>>>
    >>>>
    >>>> It looks parisc specific so am adding some parisc because this
    >>>> builds but
    >>>> I am less sure if it is actually correct. If it's correct, it
    >>>> should be
    >>>> appear before the swap-over-nfs patches to avoid bisection
    >>>> problems.
    >>>> I've added some parisc folk for review.
    >>>>
    >>>> ---8<---
    >>>> parisc: Redefine ATOMIC_INIT and ATOMIC64_INIT like other
    >>>> architectures
    >>>>
    >>>> The following build error occured during a parisc build with
    >>>> swap-over-NFS patches applied.
    >>>>
    >>>> net/core/sock.c:274:36: error: initializer element is not constant
    >>>> net/core/sock.c:274:36: error: (near initialization for
    >>>> 'memalloc_socks')
    >>>> net/core/sock.c:274:36: error: initializer element is not constant
    >>>>
    >>>> It's not obvious but this is due to how ATOMIC_INIT is defined on
    >>>> parisc. It should affect any user of STATIC_KEY_INIT_FALSE on that
    >>>> platform.
    >>>>
    >>>> This patch makes the definition of ATOMIC_INIT on parisc to look
    >>>> like
    >>>> other arches definition.
    >>>>
    >>>> Reported-by: Fengguang Wu <fengguang.wu@intel.com>
    >>>> Signed-off-by: Mel Gorman <mgorman@suse.de>
    >>>> ---
    >>>> arch/parisc/include/asm/atomic.h | 4 ++--
    >>>> 1 file changed, 2 insertions(+), 2 deletions(-)
    >>>>
    >>>> diff --git a/arch/parisc/include/asm/atomic.h b/arch/parisc/
    >>>> include/asm/atomic.h
    >>>> index 6c6defc..af9cf30 100644
    >>>> --- a/arch/parisc/include/asm/atomic.h
    >>>> +++ b/arch/parisc/include/asm/atomic.h
    >>>> @@ -141,7 +141,7 @@ static __inline__ int
    >>>> __atomic_add_unless(atomic_t *v, int a, int u)
    >>>>
    >>>> #define atomic_sub_and_test(i,v) (atomic_sub_return((i),(v)) == 0)
    >>>>
    >>>> -#define ATOMIC_INIT(i) ((atomic_t) { (i) })
    >>>> +#define ATOMIC_INIT(i) { (i) }
    >>>>
    >>>> #define smp_mb__before_atomic_dec() smp_mb()
    >>>> #define smp_mb__after_atomic_dec() smp_mb()
    >>>> @@ -150,7 +150,7 @@ static __inline__ int
    >>>> __atomic_add_unless(atomic_t *v, int a, int u)
    >>>>
    >>>> #ifdef CONFIG_64BIT
    >>>>
    >>>> -#define ATOMIC64_INIT(i) ((atomic64_t) { (i) })
    >>>> +#define ATOMIC64_INIT(i) { (i) }
    >>>>
    >>>> static __inline__ s64
    >>>> __atomic64_add_return(s64 i, atomic64_t *v)
    >>>
    >>> OK, I don't understand this either ... why would not casting to the
    >>> appropriate type suddenly stop warning about the initialiser being
    >>> non
    >>> constant. It looks like some type of gcc bug to me.
    >>

    Possibly, the cast causes the const attribute to be dropped...

    >> I agree. I could not see any functional difference as such either
    >> but also
    >> could not figure out why gcc would get it right for some arches and
    >> not
    >> for others.
    >
    > Will gcc create a temporary (and hence non constant) value for the
    > conversion?

    Parisc is a callee copies architecture. Thus, a structure passed as an
    argument may be copied to a temporary. This has been a source of
    numerous bugs as the majority of architectures do it the other way
    round.

    It would be easier to see what's happening with preprocessed source.

    >
    >>> Our toolchain
    >>> expert (Dave) hangs out on the parisc list ... he'll want to know
    >>> your
    >>> gcc -v.
    >>>
    >>
    >> I'm using the cross-compiler from
    >> ftp://ftp.kernel.org/pub/tools/crosstool/files/bin/x86_64/4.6.3/. I
    >> do
    >> not know what compiler Fengguang Wu was using.
    >
    > Yeah that's handy binaries and I'm using them in the x86 compile
    > servers. However this particular parisc-defconfig is compile tested in
    > an ia64 machine which is built from debian's gcc-4.7 source:
    >
    > Using built-in specs.
    > COLLECT_GCC=/opt/cross/bin/hppa-linux-gcc
    > COLLECT_LTO_WRAPPER=/opt/cross/libexec/gcc/hppa-linux/4.7/lto-wrapper
    > Target: hppa-linux
    > Configured with: /home/wfg/buildall/gcc-4.7-4.7.1/src/configure --
    > target=hppa-linux --enable-targets=all --prefix=/opt/cross --enable-
    > lang
    > uages=c --without-headers --enable-sjlj-exceptions --with-system-
    > libunwind --disable-nls --disable-threads --disable-shared --disable-
    > libmudflap --disable-libssp --disable-libgomp --disable-decimal-
    > float --disable-libquadmath --enable-
    > checking=release Thread model: single
    > gcc version 4.7.1 (GCC)
    >
    > Thanks,
    > Fengguang
    >
    >> Using built-in specs.
    >> COLLECT_GCC=/home/mel/git-public/cross-compilers/gcc-4.6.3-nolibc/
    >> hppa-linux/bin/hppa-linux-gcc
    >> COLLECT_LTO_WRAPPER=/home/mel/git-public/cross-compilers/gcc-4.6.3-
    >> nolibc/hppa-linux/bin/../libexec/gcc/hppa-linux/4.6.3/lto-wrapper
    >> Target: hppa-linux
    >> Configured with: /home/tony/buildall/src/gcc/configure
    >> --target=hppa-linux --host=x86_64-linux-gnu --build=x86_64-linux-gnu
    >> --enable-targets=all --prefix=/opt/cross/gcc-4.6.3-nolibc/hppa-linux/
    >> --enable-languages=c --with-newlib --without-headers
    >> --enable-sjlj-exceptions --with-system-libunwind --disable-nls
    >> --disable-threads --disable-shared --disable-libmudflap --disable-
    >> libssp
    >> --disable-libgomp --disable-decimal-float --enable-checking=release
    >> --with-mpfr=/home/tony/buildall/src/sys-x86_64
    >> --with-gmp=/home/tony/buildall/src/sys-x86_64 --disable-bootstrap
    >> --disable-libquadmath
    >> Thread model: single
    >> gcc version 4.6.3 (GCC)
    >>
    >> --
    >> Mel Gorman
    >> SUSE Labs
    > --
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    >

    --
    John David Anglin dave.anglin@bell.net





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