Re: [PATCH -mm 5/5] bpf/progs: replace hard-coded 16 with TASK_COMM_LEN

[Yafang Shao <laoar.shao@gmail.com>]

On Sun, Dec 5, 2021 at 11:13 AM Alexei Starovoitov
<alexei.starovoitov@gmail.com> wrote:
>
> On Sat, Dec 4, 2021 at 6:45 PM Yafang Shao <laoar.shao@gmail.com> wrote:
> >
> > On Sun, Dec 5, 2021 at 12:44 AM Alexei Starovoitov
> > <alexei.starovoitov@gmail.com> wrote:
> > >
> > > On Sat, Dec 4, 2021 at 1:53 AM Yafang Shao <laoar.shao@gmail.com> wrote:
> > > >
> > > >  static int process_sample(void *ctx, void *data, size_t len)
> > > >  {
> > > > -       struct sample *s = data;
> > > > +       struct sample_ringbuf *s = data;
> > >
> > > This is becoming pointless churn.
> > > Nack.
> > >
> > > > index 145028b52ad8..7b1bb73c3501 100644
> > > > --- a/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> > > > +++ b/tools/testing/selftests/bpf/progs/test_core_reloc_kernel.c
> > > > @@ -1,8 +1,7 @@
> > > >  // SPDX-License-Identifier: GPL-2.0
> > > >  // Copyright (c) 2019 Facebook
> > > >
> > > > -#include <linux/bpf.h>
> > > > -#include <stdint.h>
> > > > +#include <vmlinux.h>
> > > >  #include <stdbool.h>
> > > >  #include <bpf/bpf_helpers.h>
> > > >  #include <bpf/bpf_core_read.h>
> > > > @@ -23,11 +22,11 @@ struct core_reloc_kernel_output {
> > > >         int comm_len;
> > > >  };
> > > >
> > > > -struct task_struct {
> > > > +struct task_struct_reloc {
> > >
> > > Churn that is not even compile tested.
> >
> > It is strange that I have successfully compiled it....
> > Below is the compile log,
> >
> > $ cat make.log | grep test_core_reloc_kernel
> >   CLNG-BPF [test_maps] test_core_reloc_kernel.o
> >   GEN-SKEL [test_progs] test_core_reloc_kernel.skel.h
> >   CLNG-BPF [test_maps] test_core_reloc_kernel.o
> >   GEN-SKEL [test_progs-no_alu32] test_core_reloc_kernel.skel.h
> >
> > Also there's no error in the compile log.
>
> and ran the tests too?

My bad. I thought it was just a name change, which will work well if
it can be compiled successfully.
But it seems the task_struct in this file is a dummy struct, which
will be relocated to the real task_struct defined in the kernel.
We can't include vmlinux.h in this file, as it is for the relocation test.

-- 
Thanks
Yafang