Re: [PATCH v7 07/11] tools/bpf/bpftool/skeleton: make it adopt to task comm size change

From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Yafang Shao <laoar.shao@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Kees Cook <keescook@chromium.org>,
	Steven Rostedt <rostedt@goodmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>,
	Petr Mladek <pmladek@suse.com>,
	Peter Ziljstra <peterz@infradead.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Valentin Schneider <valentin.schneider@arm.com>,
	Qiang Zhang <qiang.zhang@windriver.com>,
	robdclark <robdclark@chromium.org>,
	Christian Brauner <christian@brauner.io>,
	Dietmar Eggemann <dietmar.eggemann@arm.com>,
	Ingo Molnar <mingo@redhat.com>,
	Juri Lelli <juri.lelli@redhat.com>,
	Vincent Guittot <vincent.guittot@linaro.org>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <kuba@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>, Martin Lau <kafai@fb.com>,
	Song Liu <songliubraving@fb.com>, Yonghong Song <yhs@fb.com>,
	john fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>,
	dennis.dalessandro@cornelisnetworks.com,
	mike.marciniszyn@cornelisnetworks.com,
	Doug Ledford <dledford@redhat.com>,
	Jason Gunthorpe <jgg@ziepe.ca>,
	linux-rdma@vger.kernel.org, Networking <netdev@vger.kernel.org>,
	bpf <bpf@vger.kernel.org>,
	"linux-perf-use." <linux-perf-users@vger.kernel.org>,
	linux-fsdevel@vger.kernel.org,
	Linux Memory Management List <linux-mm@kvack.org>,
	open list <linux-kernel@vger.kernel.org>,
	kernel test robot <oliver.sang@intel.com>,
	kbuild test robot <lkp@intel.com>,
	Alexei Starovoitov <alexei.starovoitov@gmail.com>
Subject: Re: [PATCH v7 07/11] tools/bpf/bpftool/skeleton: make it adopt to task comm size change
Date: Mon, 1 Nov 2021 16:47:42 -0700	[thread overview]
Message-ID: <CAEf4BzYEWxb+cm-cyBFMtA4mBfRfhp9dypfV+7K=wR01XYudzg@mail.gmail.com> (raw)
In-Reply-To: <20211101060419.4682-8-laoar.shao@gmail.com>

On Sun, Oct 31, 2021 at 11:04 PM Yafang Shao <laoar.shao@gmail.com> wrote:
>
> bpf_probe_read_kernel_str() will add a nul terminator to the dst, then
> we don't care about if the dst size is big enough.
>
> Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> Cc: Arnaldo Carvalho de Melo <arnaldo.melo@gmail.com>
> Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
> Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Steven Rostedt <rostedt@goodmis.org>
> Cc: Al Viro <viro@zeniv.linux.org.uk>
> Cc: Kees Cook <keescook@chromium.org>
> Cc: Petr Mladek <pmladek@suse.com>
> ---

LGTM.

Acked-by: Andrii Nakryiko <andrii@kernel.org>

>  tools/bpf/bpftool/skeleton/pid_iter.bpf.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
> index d9b420972934..f70702fcb224 100644
> --- a/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
> +++ b/tools/bpf/bpftool/skeleton/pid_iter.bpf.c
> @@ -71,8 +71,8 @@ int iter(struct bpf_iter__task_file *ctx)
>
>         e.pid = task->tgid;
>         e.id = get_obj_id(file->private_data, obj_type);
> -       bpf_probe_read_kernel(&e.comm, sizeof(e.comm),
> -                             task->group_leader->comm);
> +       bpf_probe_read_kernel_str(&e.comm, sizeof(e.comm),
> +                                 task->group_leader->comm);
>         bpf_seq_write(ctx->meta->seq, &e, sizeof(e));
>
>         return 0;
> --
> 2.17.1
>