Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 26 Oct 2021 16:48:10 -0700 (PDT)
Subject:     Re: [PATCH 0/2] ftrace: make sure preemption disabled on recursion testing
In-Reply-To: <8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com>
CC:     guoren@kernel.org, rostedt@goodmis.org, mingo@redhat.com,
        James.Bottomley@HansenPartnership.com, deller@gmx.de,
        mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org,
        Paul Walmsley <paul.walmsley@sifive.com>,
        aou@eecs.berkeley.edu, tglx@linutronix.de, bp@alien8.de,
        x86@kernel.org, hpa@zytor.com, jpoimboe@redhat.com,
        jikos@kernel.org, mbenes@suse.cz, pmladek@suse.com,
        joe.lawrence@redhat.com, colin.king@canonical.com,
        mhiramat@kernel.org, peterz@infradead.org, npiggin@gmail.com,
        jszhang@kernel.org, linux-csky@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org,
        live-patching@vger.kernel.org
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     yun.wang@linux.alibaba.com
Message-ID: <mhng-95994d12-e1d9-43b3-bef0-c5c844ffcf86@palmerdabbelt-glaptop>
Mime-Version: 1.0 (MHng)
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk

On Mon, 11 Oct 2021 22:39:16 PDT (-0700), yun.wang@linux.alibaba.com wrote:
> The testing show that perf_ftrace_function_call() are using
> smp_processor_id() with preemption enabled, all the checking
> on CPU could be wrong after preemption, PATCH 1/2 will fix
> that.
>
> Besides, as Peter point out, the testing of recursion within
> the section between ftrace_test_recursion_trylock()/_unlock()
> pair also need the preemption disabled as the documentation
> explained, PATCH 2/2 will make sure on that.
>
> Michael Wang (2):
>   ftrace: disable preemption on the testing of recursion
>   ftrace: prevent preemption in perf_ftrace_function_call()
>
>  arch/csky/kernel/probes/ftrace.c     |  2 --
>  arch/parisc/kernel/ftrace.c          |  2 --
>  arch/powerpc/kernel/kprobes-ftrace.c |  2 --
>  arch/riscv/kernel/probes/ftrace.c    |  2 --
>  arch/x86/kernel/kprobes/ftrace.c     |  2 --
>  include/linux/trace_recursion.h      | 10 +++++++++-
>  kernel/livepatch/patch.c             |  6 ------
>  kernel/trace/trace_event_perf.c      | 17 +++++++++++++----
>  kernel/trace/trace_functions.c       |  5 -----
>  9 files changed, 22 insertions(+), 26 deletions(-)

Acked-by: Palmer Dabbelt <palmerdabbelt@google.com> # RISC-V