[PATCH bpf-next] libbpf: Fix include of bpf_helpers.h when libbpf is installed on system

[PATCH bpf-next] libbpf: Fix include of bpf_helpers.h when libbpf is installed on system

[Toke Høiland-Jørgensen]

The change to use angled includes for bpf_helper_defs.h breaks compilation
against libbpf when it is installed in the include path, since the file is
installed in the bpf/ subdirectory of $INCLUDE_PATH. Fix this by adding the
bpf/ prefix to the #include directive.

Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
---
Not actually sure this fix works for all the cases you originally tried to
fix with the referred commit; please check. Also, could we please stop breaking
libbpf builds? :)

 tools/lib/bpf/bpf_helpers.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
index 050bb7bf5be6..fa43d649e7a2 100644
--- a/tools/lib/bpf/bpf_helpers.h
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -2,7 +2,7 @@
 #ifndef __BPF_HELPERS__
 #define __BPF_HELPERS__
 
-#include <bpf_helper_defs.h>
+#include <bpf/bpf_helper_defs.h>
 
 #define __uint(name, val) int (*name)[val]
 #define __type(name, val) typeof(val) *name
-- 
2.24.1

Re: [PATCH bpf-next] libbpf: Fix include of bpf_helpers.h when libbpf is installed on system

[Andrii Nakryiko]

On Tue, Jan 14, 2020 at 8:43 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>
> The change to use angled includes for bpf_helper_defs.h breaks compilation
> against libbpf when it is installed in the include path, since the file is
> installed in the bpf/ subdirectory of $INCLUDE_PATH. Fix this by adding the
> bpf/ prefix to the #include directive.
>
> Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
> Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> ---
> Not actually sure this fix works for all the cases you originally tried to

This does break selftests/bpf. Have you tried building selftests, does
it work for you? We need to fix selftests simultaneously with this
change.

> fix with the referred commit; please check. Also, could we please stop breaking
> libbpf builds? :)

Which libbpf build is failing right now? Both github and in-kernel
libbpf builds are fine. You must be referring to something else. What
exactly?

>
>  tools/lib/bpf/bpf_helpers.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
> index 050bb7bf5be6..fa43d649e7a2 100644
> --- a/tools/lib/bpf/bpf_helpers.h
> +++ b/tools/lib/bpf/bpf_helpers.h
> @@ -2,7 +2,7 @@
>  #ifndef __BPF_HELPERS__
>  #define __BPF_HELPERS__
>
> -#include <bpf_helper_defs.h>
> +#include <bpf/bpf_helper_defs.h>
>
>  #define __uint(name, val) int (*name)[val]
>  #define __type(name, val) typeof(val) *name
> --
> 2.24.1
>

Re: [PATCH bpf-next] libbpf: Fix include of bpf_helpers.h when libbpf is installed on system

[Andrii Nakryiko]

On Tue, Jan 14, 2020 at 11:07 AM Andrii Nakryiko
<andrii.nakryiko@gmail.com> wrote:
>
> On Tue, Jan 14, 2020 at 8:43 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> >
> > The change to use angled includes for bpf_helper_defs.h breaks compilation
> > against libbpf when it is installed in the include path, since the file is
> > installed in the bpf/ subdirectory of $INCLUDE_PATH. Fix this by adding the
> > bpf/ prefix to the #include directive.
> >
> > Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
> > Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> > ---
> > Not actually sure this fix works for all the cases you originally tried to
>
> This does break selftests/bpf. Have you tried building selftests, does
> it work for you? We need to fix selftests simultaneously with this
> change.
>
> > fix with the referred commit; please check. Also, could we please stop breaking
> > libbpf builds? :)
>
> Which libbpf build is failing right now? Both github and in-kernel
> libbpf builds are fine. You must be referring to something else. What
> exactly?

I think it's better to just ensure that when compiling BPF programs,
they have -I/usr/include/bpf specified, so that all BPF-side headers
can be simply included as #include <bpf_helpers.h>, #include
<bpf_tracing.h>, etc

>
> >
> >  tools/lib/bpf/bpf_helpers.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/lib/bpf/bpf_helpers.h b/tools/lib/bpf/bpf_helpers.h
> > index 050bb7bf5be6..fa43d649e7a2 100644
> > --- a/tools/lib/bpf/bpf_helpers.h
> > +++ b/tools/lib/bpf/bpf_helpers.h
> > @@ -2,7 +2,7 @@
> >  #ifndef __BPF_HELPERS__
> >  #define __BPF_HELPERS__
> >
> > -#include <bpf_helper_defs.h>
> > +#include <bpf/bpf_helper_defs.h>
> >
> >  #define __uint(name, val) int (*name)[val]
> >  #define __type(name, val) typeof(val) *name
> > --
> > 2.24.1
> >

Re: [PATCH bpf-next] libbpf: Fix include of bpf_helpers.h when libbpf is installed on system

[Toke Høiland-Jørgensen]

Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:

> On Tue, Jan 14, 2020 at 11:07 AM Andrii Nakryiko
> <andrii.nakryiko@gmail.com> wrote:
>>
>> On Tue, Jan 14, 2020 at 8:43 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>> >
>> > The change to use angled includes for bpf_helper_defs.h breaks compilation
>> > against libbpf when it is installed in the include path, since the file is
>> > installed in the bpf/ subdirectory of $INCLUDE_PATH. Fix this by adding the
>> > bpf/ prefix to the #include directive.
>> >
>> > Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
>> > Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>> > ---
>> > Not actually sure this fix works for all the cases you originally tried to
>>
>> This does break selftests/bpf. Have you tried building selftests, does
>> it work for you? We need to fix selftests simultaneously with this
>> change.
>>
>> > fix with the referred commit; please check. Also, could we please stop breaking
>> > libbpf builds? :)
>>
>> Which libbpf build is failing right now? Both github and in-kernel
>> libbpf builds are fine. You must be referring to something else. What
>> exactly?
>
> I think it's better to just ensure that when compiling BPF programs,
> they have -I/usr/include/bpf specified, so that all BPF-side headers
> can be simply included as #include <bpf_helpers.h>, #include
> <bpf_tracing.h>, etc

And break all programs that don't have that already? Just to make the
kernel build env slightly more convenient? Hardly friendly to the
library users, is it? :)

As far as selftests are concerned, I finally managed to get an LLVM
version that will build them all; so I'll test that tomorrow and send a
v2 that doesn't break them...

-Toke

Re: [PATCH bpf-next] libbpf: Fix include of bpf_helpers.h when libbpf is installed on system

[Alexei Starovoitov]

On Tue, Jan 14, 2020 at 10:26:57PM +0100, Toke Høiland-Jørgensen wrote:
> Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:
> 
> > On Tue, Jan 14, 2020 at 11:07 AM Andrii Nakryiko
> > <andrii.nakryiko@gmail.com> wrote:
> >>
> >> On Tue, Jan 14, 2020 at 8:43 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
> >> >
> >> > The change to use angled includes for bpf_helper_defs.h breaks compilation
> >> > against libbpf when it is installed in the include path, since the file is
> >> > installed in the bpf/ subdirectory of $INCLUDE_PATH. Fix this by adding the
> >> > bpf/ prefix to the #include directive.
> >> >
> >> > Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
> >> > Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
> >> > ---
> >> > Not actually sure this fix works for all the cases you originally tried to
> >>
> >> This does break selftests/bpf. Have you tried building selftests, does
> >> it work for you? We need to fix selftests simultaneously with this
> >> change.
> >>
> >> > fix with the referred commit; please check. Also, could we please stop breaking
> >> > libbpf builds? :)
> >>
> >> Which libbpf build is failing right now? Both github and in-kernel
> >> libbpf builds are fine. You must be referring to something else. What
> >> exactly?
> >
> > I think it's better to just ensure that when compiling BPF programs,
> > they have -I/usr/include/bpf specified, so that all BPF-side headers
> > can be simply included as #include <bpf_helpers.h>, #include
> > <bpf_tracing.h>, etc
> 
> And break all programs that don't have that already? Just to make the
> kernel build env slightly more convenient? Hardly friendly to the
> library users, is it? :)

Could you explain the breakage ?
bpf_helpers.h and bpf_helper_defs.h are installed in the same location.
If prefix==/usr during make install of libbpf they both will go into
/usr/include/bpf

Are you saying the bpf progs had:
#include <bpf/bpf_helpers.h>
to pick that header from /usr/include and commit 6910d7d3867a that did:
+++ b/tools/lib/bpf/bpf_helpers.h
@@ -2,7 +2,7 @@
 #ifndef __BPF_HELPERS__
 #define __BPF_HELPERS__

-#include "bpf_helper_defs.h"
+#include <bpf_helper_defs.h>
broke it?
If so this bit needs to be reverted.
And we need a selfttest for such include order.

Re: [PATCH bpf-next] libbpf: Fix include of bpf_helpers.h when libbpf is installed on system

[Toke Høiland-Jørgensen]

Alexei Starovoitov <alexei.starovoitov@gmail.com> writes:

> On Tue, Jan 14, 2020 at 10:26:57PM +0100, Toke Høiland-Jørgensen wrote:
>> Andrii Nakryiko <andrii.nakryiko@gmail.com> writes:
>> 
>> > On Tue, Jan 14, 2020 at 11:07 AM Andrii Nakryiko
>> > <andrii.nakryiko@gmail.com> wrote:
>> >>
>> >> On Tue, Jan 14, 2020 at 8:43 AM Toke Høiland-Jørgensen <toke@redhat.com> wrote:
>> >> >
>> >> > The change to use angled includes for bpf_helper_defs.h breaks compilation
>> >> > against libbpf when it is installed in the include path, since the file is
>> >> > installed in the bpf/ subdirectory of $INCLUDE_PATH. Fix this by adding the
>> >> > bpf/ prefix to the #include directive.
>> >> >
>> >> > Fixes: 6910d7d3867a ("selftests/bpf: Ensure bpf_helper_defs.h are taken from selftests dir")
>> >> > Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
>> >> > ---
>> >> > Not actually sure this fix works for all the cases you originally tried to
>> >>
>> >> This does break selftests/bpf. Have you tried building selftests, does
>> >> it work for you? We need to fix selftests simultaneously with this
>> >> change.
>> >>
>> >> > fix with the referred commit; please check. Also, could we please stop breaking
>> >> > libbpf builds? :)
>> >>
>> >> Which libbpf build is failing right now? Both github and in-kernel
>> >> libbpf builds are fine. You must be referring to something else. What
>> >> exactly?
>> >
>> > I think it's better to just ensure that when compiling BPF programs,
>> > they have -I/usr/include/bpf specified, so that all BPF-side headers
>> > can be simply included as #include <bpf_helpers.h>, #include
>> > <bpf_tracing.h>, etc
>> 
>> And break all programs that don't have that already? Just to make the
>> kernel build env slightly more convenient? Hardly friendly to the
>> library users, is it? :)
>
> Could you explain the breakage ?
> bpf_helpers.h and bpf_helper_defs.h are installed in the same location.
> If prefix==/usr during make install of libbpf they both will go into
> /usr/include/bpf
>
> Are you saying the bpf progs had:
> #include <bpf/bpf_helpers.h>
> to pick that header from /usr/include and commit 6910d7d3867a that did:
> +++ b/tools/lib/bpf/bpf_helpers.h
> @@ -2,7 +2,7 @@
>  #ifndef __BPF_HELPERS__
>  #define __BPF_HELPERS__
>
> -#include "bpf_helper_defs.h"
> +#include <bpf_helper_defs.h>
> broke it?

Yes. I get this error in xdp-tools[0] when updating lib/libbpf to the
latest upstream from github:

In file included from xdpfilt_blk_udp.c:10:
In file included from ./xdpfilt_prog.h:12:
../lib/libbpf/src/root/usr/include/bpf/bpf_helpers.h:5:10: error: 'bpf_helper_defs.h' file not found with <angled> include; use "quotes" instead
#include <bpf_helper_defs.h>
         ^~~~~~~~~~~~~~~~~~~
         "bpf_helper_defs.h"
1 error generated.

> If so this bit needs to be reverted.
> And we need a selfttest for such include order.

Yes, please! :)
Trying to convince the selftests Makefile to do the right thing; will
send a v2 of this patch if I succeed...

-Toke

[0] https://github.com/xdp-project/xdp-tools