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Date: Tue, 26 Oct 2021 16:48:10 -0700 (PDT)
X-Google-Original-Date: Tue, 26 Oct 2021 16:24:16 PDT (-0700)
Subject: Re: [PATCH 0/2] ftrace: make sure preemption disabled on recursion
 testing
In-Reply-To: <8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com>
From: Palmer Dabbelt <palmer@dabbelt.com>
To: yun.wang@linux.alibaba.com
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Cc: peterz@infradead.org, Paul Walmsley <paul.walmsley@sifive.com>,
 James.Bottomley@HansenPartnership.com, guoren@kernel.org, jszhang@kernel.org,
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 aou@eecs.berkeley.edu, jikos@kernel.org, rostedt@goodmis.org, bp@alien8.de,
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 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

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