netdev - Re: [PATCH bpf-next 2/2] selftests/bpf: add loop test 5

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Message-ID: <20190805161626.dil4xkmrdlqhqhzd@ast-mbp>
Date:   Mon, 5 Aug 2019 09:16:27 -0700
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Yonghong Song <yhs@...com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "daniel@...earbox.net" <daniel@...earbox.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "bpf@...r.kernel.org" <bpf@...r.kernel.org>,
        Kernel Team <Kernel-team@...com>
Subject: Re: [PATCH bpf-next 2/2] selftests/bpf: add loop test 5

On Sun, Aug 04, 2019 at 05:45:23AM +0000, Yonghong Song wrote:
> 
> 
> On 8/2/19 4:33 PM, Alexei Starovoitov wrote:
> > Add a test with multiple exit conditions.
> > It's not an infinite loop only when the verifier can properly track
> > all math on variable 'i' through all possible ways of executing this loop.
> 
> Agreed with motivation of this test.
> 
> > 
> > barrier()s are needed to disable llvm optimization that combines multiple
> > branches into fewer branches.
> > 
> > Signed-off-by: Alexei Starovoitov <ast@...nel.org>
> > ---
> >   .../bpf/prog_tests/bpf_verif_scale.c          |  1 +
> >   tools/testing/selftests/bpf/progs/loop5.c     | 37 +++++++++++++++++++
> >   2 files changed, 38 insertions(+)
> >   create mode 100644 tools/testing/selftests/bpf/progs/loop5.c
> > 
> > diff --git a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
> > index 757e39540eda..29615a4a9362 100644
> > --- a/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
> > +++ b/tools/testing/selftests/bpf/prog_tests/bpf_verif_scale.c
> > @@ -72,6 +72,7 @@ void test_bpf_verif_scale(void)
> >   		{ "loop1.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
> >   		{ "loop2.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
> >   		{ "loop4.o", BPF_PROG_TYPE_RAW_TRACEPOINT }, > +		{ "loop5.o", BPF_PROG_TYPE_RAW_TRACEPOINT },
> 
> More like a BPF_PROG_TYPE_SCHED_CLS type although probably it does not 
> matter as we did not attach it to anywhere?

right. will fix.

> >   
> >   		/* partial unroll. 19k insn in a loop.
> >   		 * Total program size 20.8k insn.
> > diff --git a/tools/testing/selftests/bpf/progs/loop5.c b/tools/testing/selftests/bpf/progs/loop5.c
> > new file mode 100644
> > index 000000000000..9d9817efe208
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/loop5.c
> > @@ -0,0 +1,37 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +// Copyright (c) 2019 Facebook
> > +#include <linux/sched.h>
> > +#include <linux/ptrace.h>
> 
> The above headers probably not needed.

will fix