Re: [Qemu-devel] [PATCH] memfd: fix configure test

[Paolo Bonzini <pbonzini@redhat.com>]

On 28/11/2017 12:42, Marc-André Lureau wrote:
> Hi
> 
> On Tue, Nov 28, 2017 at 12:32 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
>> Recent glibc added memfd_create in sys/mman.h.  This conflicts with
>> the definition in util/memfd.c:
>>
>>     /builddir/build/BUILD/qemu-2.11.0-rc1/util/memfd.c:40:12: error: static declaration of memfd_create follows non-static declaration
>>
>> Fix the configure test, and remove the sys/memfd.h inclusion since the
>> file actually does not exist---it is a typo in the memfd_create(2) man
>> page.
>>
> 
> It is introduced by this commit, right?
> https://sourceware.org/git/?p=glibc.git;a=commit;h=59d2cbb1fe4b8601d5cbd359c3806973eab6c62d
> 
> (I added Florian Weimer in cc)
> 
> So it's not part of glibc release yet.
> 
> Couldn't the declarations be put in sys/memfd.h like the man claimed
> it would be for > 1y?

Yeah, that would have been better---certainly other software than QEMU
is likely to have a static memfd_create declaration, and polluting
sys/mman.h is going to trigger the same error.  However, at least
systemd seems to have changed the test to sys/mman.h
(https://github.com/systemd/systemd/pull/7468), so I think we should
follow their lead now

Thanks,

Paolo

> 
>> Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>>  configure    | 2 +-
>>  util/memfd.c | 4 +---
>>  2 files changed, 2 insertions(+), 4 deletions(-)
>>
>> diff --git a/configure b/configure
>> index e31d6a7fee..11eac205ec 100755
>> --- a/configure
>> +++ b/configure
>> @@ -3910,7 +3910,7 @@ fi
>>  # check if memfd is supported
>>  memfd=no
>>  cat > $TMPC << EOF
>> -#include <sys/memfd.h>
>> +#include <sys/mman.h>
>>
>>  int main(void)
>>  {
>> diff --git a/util/memfd.c b/util/memfd.c
>> index 4571d1aba8..412e94a405 100644
>> --- a/util/memfd.c
>> +++ b/util/memfd.c
>> @@ -31,9 +31,7 @@
>>
>>  #include "qemu/memfd.h"
>>
>> -#ifdef CONFIG_MEMFD
>> -#include <sys/memfd.h>
>> -#elif defined CONFIG_LINUX
>> +#if defined CONFIG_LINUX && !defined CONFIG_MEMFD
>>  #include <sys/syscall.h>
>>  #include <asm/unistd.h>
>> --
>> 2.14.3
>>
>>
> 
> 
>