On 20 December 2016 at 06:32, Arnaldo Carvalho de Melo <a...@kernel.org> wrote:
> Em Tue, Dec 20, 2016 at 11:18:51AM -0300, Arnaldo Carvalho de Melo escreveu:
>> Em Wed, Dec 14, 2016 at 02:43:40PM -0800, Joe Stringer escreveu:
>> > Commit d8c5b17f2bc0 ("samples: bpf: add userspace example for attaching
>> > eBPF programs to cgroups") added these functions to samples/libbpf, but
>> > during this merge all of the samples libbpf functionality is shifting to
>> > tools/lib/bpf. Shift these functions there.
>> >
>> > Signed-off-by: Joe Stringer <j...@ovn.org>
>> > ---
>> > Arnaldo, this is a new patch you didn't previously review which I've
>> > prepared due to the conflict with net-next. I figured it's better to try
>> > to get samples/bpf properly switched over this window rather than defer the
>> > problem and end up having to deal with another merge problem next time
>> > around. I hope that is fine for you. If not, this patch onwards will need
>> > to be dropped
>> >
>> > It's a simple copy/paste/delete with a minor change for sys_bpf() vs
>> > syscall().
>> > ---
>> > samples/bpf/libbpf.c | 21 ---------------------
>> > samples/bpf/libbpf.h | 3 ---
>> > tools/lib/bpf/bpf.c | 21 +++++++++++++++++++++
>> > tools/lib/bpf/bpf.h | 3 +++
>> > 4 files changed, 24 insertions(+), 24 deletions(-)
>> >
>> > diff --git a/samples/bpf/libbpf.c b/samples/bpf/libbpf.c
>> > index 3391225ad7e9..d9af876b4a2c 100644
>> > --- a/samples/bpf/libbpf.c
>> > +++ b/samples/bpf/libbpf.c
>> > @@ -11,27 +11,6 @@
>> > #include <arpa/inet.h>
>> > #include "libbpf.h"
>> >
>> > -int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type)
>> > -{
>> > - union bpf_attr attr = {
>> > - .target_fd = target_fd,
>> > - .attach_bpf_fd = prog_fd,
>> > - .attach_type = type,
>> > - };
>> > -
>> > - return syscall(__NR_bpf, BPF_PROG_ATTACH, &attr, sizeof(attr));
>>
>> This one makes it fail for CentOS 5 and 6, others may fail as well,
>> still building, investigating...
>
> Ok, fixed it by making it follow the model of the other sys_bpf wrappers
> setting up that bpf_attr union wrt initializing unamed struct members:
>
> int bpf_prog_attach(int prog_fd, int target_fd, enum bpf_attach_type type)
> {
> - union bpf_attr attr = {
> - .target_fd = target_fd,
> - .attach_bpf_fd = prog_fd,
> - .attach_type = type,
> - };
> + union bpf_attr attr;
> +
> + bzero(&attr, sizeof(attr));
> + attr.target_fd = target_fd;
> + attr.attach_bpf_fd = prog_fd;
> + attr.attach_type = type;
>
> return sys_bpf(BPF_PROG_ATTACH, &attr, sizeof(attr));
> }
Ah, I just shifted these across originally so the delta would be
minimal but now I know why this code is like this. Thanks.
