Re: [PATCH v2 0/2] fix & prevent the missing preemption disabling

From: 王贇 <yun.wang@linux.alibaba.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Guo Ren <guoren@kernel.org>, Ingo Molnar <mingo@redhat.com>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Helge Deller <deller@gmx.de>,
	Michael Ellerman <mpe@ellerman.id.au>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Paul Mackerras <paulus@samba.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	Palmer Dabbelt <palmer@dabbelt.com>,
	Albert Ou <aou@eecs.berkeley.edu>,
	Thomas Gleixner <tglx@linutronix.de>,
	Borislav Petkov <bp@alien8.de>,
	x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Jiri Kosina <jikos@kernel.org>, Miroslav Benes <mbenes@suse.cz>,
	Petr Mladek <pmladek@suse.com>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Colin Ian King <colin.king@canonical.com>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Nicholas Piggin <npiggin@gmail.com>,
	Jisheng Zhang <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
Subject: Re: [PATCH v2 0/2] fix & prevent the missing preemption disabling
Date: Wed, 13 Oct 2021 11:33:27 +0800	[thread overview]
Message-ID: <69e9cf98-883c-0016-4b07-12afbf138094@linux.alibaba.com> (raw)
In-Reply-To: <20211012232658.7dac3f43@oasis.local.home>

On 2021/10/13 上午11:26, Steven Rostedt wrote:
> Please start a new thread when sending new versions. v2 should not be a
> reply to v1. If you want to reference v1, just add it to the cover
> letter with a link tag:
> 
> Link: https://lore.kernel.org/all/8c7de46d-9869-aa5e-2bb9-5dbc2eda395e@linux.alibaba.com/

Ok, I'll resend it with link then.

Regards,
Michael Wang

> 
> -- Steve
> 
> 
> On Wed, 13 Oct 2021 11:16:56 +0800
> 王贇 <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.
>>
>> As Peter point out, the section between ftrace_test_recursion_trylock/unlock()
>> pair require the preemption to be disabled as 'Documentation/trace/ftrace-uses.rst'
>> explained, but currently the work is done outside of the helpers.
>>
>> 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.
>>
>> Michael Wang (2):
>>   ftrace: disable preemption between ftrace_test_recursion_trylock/unlock()
>>   ftrace: do CPU checking after preemption disabled
>>
>>  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(-)
>>