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

From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Kees Cook <keescook@chromium.org>, Petr Mladek <pmladek@suse.com>,
	David Hildenbrand <david@redhat.com>,
	Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	Andrii Nakryiko <andrii.nakryiko@gmail.com>,
	linux-mm <linux-mm@kvack.org>, bpf <bpf@vger.kernel.org>,
	"linux-perf-use." <linux-perf-users@vger.kernel.org>,
	Linux-Fsdevel <linux-fsdevel@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Michal Miroslaw <mirq-linux@rere.qmqm.pl>,
	Peter Zijlstra <peterz@infradead.org>,
	Matthew Wilcox <willy@infradead.org>,
	Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH -mm 5/5] bpf/progs: replace hard-coded 16 with TASK_COMM_LEN
Date: Sat, 4 Dec 2021 19:13:24 -0800	[thread overview]
Message-ID: <CAADnVQLu+RWSeMfOe5eBuTsp9gxPsFC_bRTXoWmvWP+Lv_rZzQ@mail.gmail.com> (raw)
In-Reply-To: <CALOAHbCud62ivvoRuz1SV-d3sL9Y9knEga0N-jiXnM3SYzWxNA@mail.gmail.com>

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?