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Date: Tue, 12 Oct 2021 23:26:58 -0400
From: Steven Rostedt <rostedt@goodmis.org>
To: =?UTF-8?B?546L6LSH?= <yun.wang@linux.alibaba.com>
Subject: Re: [PATCH v2 0/2] fix & prevent the missing preemption disabling
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Cc: "Peter Zijlstra \(Intel\)" <peterz@infradead.org>,
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 Petr Mladek <pmladek@suse.com>, Albert Ou <aou@eecs.berkeley.edu>,
 Jiri Kosina <jikos@kernel.org>, Nicholas Piggin <npiggin@gmail.com>,
 Borislav Petkov <bp@alien8.de>, Josh Poimboeuf <jpoimboe@redhat.com>,
 Thomas Gleixner <tglx@linutronix.de>, linux-parisc@vger.kernel.org,
 linux-kernel@vger.kernel.org, Palmer Dabbelt <palmer@dabbelt.com>,
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 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

Please start a new thread when sending new versions. v2 should not be a
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Link: https://lore.kernel.org/all/8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linu=
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-- Steve


On Wed, 13 Oct 2021 11:16:56 +0800
=E7=8E=8B=E8=B4=87 <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 pre=
emption.
>=20
> As Peter point out, the section between ftrace_test_recursion_trylock/unl=
ock()
> pair require the preemption to be disabled as 'Documentation/trace/ftrace=
-uses.rst'
> explained, but currently the work is done outside of the helpers.
>=20
> Patch 1/2 will make sure preemption disabled after trylock() succeed,
> patch 2/2 will do smp_processor_id() checking after trylock to address the
> issue.
>=20
> Michael Wang (2):
>   ftrace: disable preemption between ftrace_test_recursion_trylock/unlock=
()
>   ftrace: do CPU checking after preemption disabled
>=20
>  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      | 22 +++++++++++++++++++++-
>  kernel/livepatch/patch.c             |  6 ------
>  kernel/trace/trace_event_perf.c      |  6 +++---
>  kernel/trace/trace_functions.c       |  5 -----
>  9 files changed, 24 insertions(+), 25 deletions(-)
>=20