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

[Tonghao Zhang <xiangxia.m.yue@gmail.com>]

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));
+       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);
+       int r = write(fdset->u.writefd, "1", 1);
+       RTE_SET_USED(r);
 }

On Fri, Mar 30, 2018 at 10:28 PM, Timothy Redaelli <tredaelli@redhat.com> wrote:
> On Fri, 30 Mar 2018 15:27:55 +0200
> Maxime Coquelin <maxime.coquelin@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
>