[dpdk-dev] Build is broken in dpdk-next-net

[Maxime Coquelin]

Thanks Xiangxia,

I can post it, do you agree if I add below comments?

On 03/30/2018 04:47 PM, Tonghao Zhang wrote:
> I rebuild it on ubuntu 17.10 and cash it. I use the 'RTE_SET_USED' to fix it.
> 
> 
> diff --git a/lib/librte_vhost/fd_man.c b/lib/librte_vhost/fd_man.c
> index 771675718..f11803191 100644
> --- a/lib/librte_vhost/fd_man.c
> +++ b/lib/librte_vhost/fd_man.c
> @@ -279,7 +279,8 @@ fdset_pipe_read_cb(int readfd, void *dat __rte_unused,
>                     int *remove __rte_unused)
>   {
>          char charbuf[16];
> -       read(readfd, charbuf, sizeof(charbuf));
> +       int r = read(readfd, charbuf, sizeof(charbuf));
/* Just an optimization, we don't care if read() failed so ignore 
explicitly its return value to make the compiler happy */
> +       RTE_SET_USED(r);
>   }
> 
>   void
> @@ -319,5 +320,6 @@ fdset_pipe_init(struct fdset *fdset)
>   void
>   fdset_pipe_notify(struct fdset *fdset)
>   {
> -       write(fdset->u.writefd, "1", 1);
/* Just an optimization, we don't care if write() failed so ignore 
explicitly its return value to make the compiler happy */
> +       int r = write(fdset->u.writefd, "1", 1);
> +       RTE_SET_USED(r);
>   }
> 
> On Fri, Mar 30, 2018 at 10:28 PM, Timothy Redaelli <tredaelli at redhat.com> wrote:
>> On Fri, 30 Mar 2018 15:27:55 +0200
>> Maxime Coquelin <maxime.coquelin at redhat.com> wrote:
>>
>>> Hi Andrew,
>>>
>>> On 03/30/2018 03:18 PM, Andrew Rybchenko wrote:
>>>> Hi all,
>>>>
>>>> Build is broken in dpdk-next-net for me on Ubuntu 16.04.4:
>>>>
>>>> lib/librte_vhost/fd_man.c: In function ‘fdset_pipe_read_cb’:
>>>> lib/librte_vhost/fd_man.c:284:2: error: ignoring return value of
>>>> ‘read’, declared with attribute warn_unused_result
>>>> [-Werror=unused-result] read(readfd, charbuf, sizeof(charbuf)); ^
>>>> lib/librte_vhost/fd_man.c: In function ‘fdset_pipe_notify’:
>>>> lib/librte_vhost/fd_man.c:324:2: error: ignoring return value of
>>>> ‘write’, declared with attribute warn_unused_result
>>>> [-Werror=unused-result] write(fdset->u.writefd, "1", 1); ^
>>>>
>>>> $ gcc --version
>>>> gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609
>>>
>>> Thanks for reporting, I don't catch it with my Fedora build system:
>>> $ gcc --version
>>> gcc (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5)
>>
>> Those kind of warnings are enabled by "-D_FORTIFY_SOURCE=2" (enabled by
>> default in Ubuntu [1]).
>>
>> To have the same behavior on Fedora you need to set -D_FORTIFY_SOURCE=2
>> by hand, for example with:
>>
>> # make EXTRA_CFLAGS="-D_FORTIFY_SOURCE=2"
>>
>> Usually I build dpdk with the flags we also use when we build the
>> Fedora/RHEL package. To do that I have in my .bashrc (all in one line):
>>
>> export EXTRA_CFLAGS="-O2 -g -pipe -Werror=format-security
>> -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong
>> --param=ssp-buffer-size=4 -grecord-gcc-switches
>> -specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic
>> -fasynchronous-unwind-tables -Wformat"
>>
>>>>
>>>> As I understand it is broken in
>>>> ad94ade905454401b705be9e06b19e54a1c78148 vhost: add pipe event for
>>>> optimizing negotiating
>>>
>>> I confirm it is this patch.
>>>
>>> Xiangxia, can you provide a fix please?
>>>
>>> Ferruh, how do you want to proceed?
>>> Would you revert it?
>>>
>>> Thanks,
>>> Maxime
>>>> Andrew.
>>>>
>>
>> [1]
>> https://wiki.ubuntu.com/ToolChain/CompilerFlags#A-D_FORTIFY_SOURCE.3D2
>>