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From: 王贇 <yun.wang@linux.alibaba.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: "Peter Zijlstra \(Intel\)" <peterz@infradead.org>,
	Paul Walmsley <paul.walmsley@sifive.com>,
	"James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
	Guo Ren <guoren@kernel.org>, Jisheng Zhang <jszhang@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	live-patching@vger.kernel.org, linux-riscv@lists.infradead.org,
	Miroslav Benes <mbenes@suse.cz>,
	Paul Mackerras <paulus@samba.org>,
	Joe Lawrence <joe.lawrence@redhat.com>,
	Helge Deller <deller@gmx.de>,
	x86@kernel.org, linux-csky@vger.kernel.org,
	Ingo Molnar <mingo@redhat.com>, 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>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Colin Ian King <colin.king@canonical.com>,
	linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH 1/2] ftrace: disable preemption on the testing of recursion
Date: Wed, 13 Oct 2021 09:46:42 +0800	[thread overview]
Message-ID: <d079d249-b603-230a-a905-3f0df55056ae@linux.alibaba.com> (raw)
In-Reply-To: <20211012081728.5d357d6c@gandalf.local.home>



On 2021/10/12 下午8:17, Steven Rostedt wrote:
> On Tue, 12 Oct 2021 13:40:08 +0800
> 王贇 <yun.wang@linux.alibaba.com> wrote:
> 
>> @@ -52,11 +52,6 @@ static void notrace klp_ftrace_handler(unsigned long ip,
>>  	bit = ftrace_test_recursion_trylock(ip, parent_ip);
>>  	if (WARN_ON_ONCE(bit < 0))
>>  		return;
>> -	/*
>> -	 * A variant of synchronize_rcu() is used to allow patching functions
>> -	 * where RCU is not watching, see klp_synchronize_transition().
>> -	 */
> 
> I have to take a deeper look at this patch set, but do not remove this
> comment, as it explains the protection here, that is not obvious with the
> changes you made.

Will keep that in v2.

Regards,
Michael Wang

> 
> -- Steve
> 
> 
>> -	preempt_disable_notrace();
>>
>>  	func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
>>  				      stack_node);

  reply	other threads:[~2021-10-13  1:48 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-12  5:39 [PATCH 0/2] ftrace: make sure preemption disabled on recursion testing 王贇
2021-10-12  5:40 ` [PATCH 1/2] ftrace: disable preemption on the testing of recursion 王贇
2021-10-12 12:17   ` Steven Rostedt
2021-10-13  1:46     ` 王贇 [this message]
2021-10-12 12:24   ` Miroslav Benes
2021-10-12 12:29     ` Steven Rostedt
2021-10-13  1:52       ` 王贇
2021-10-13  1:50     ` 王贇
2021-10-13  2:27       ` Steven Rostedt
2021-10-13  2:36         ` 王贇
2021-10-12 12:43   ` Steven Rostedt
2021-10-13  2:04     ` 王贇
2021-10-13  2:30       ` Steven Rostedt
2021-10-13  2:38         ` 王贇
2021-10-12  5:40 ` [PATCH 2/2] ftrace: prevent preemption in perf_ftrace_function_call() 王贇
2021-10-12 11:20   ` Peter Zijlstra
2021-10-13  1:45     ` 王贇
2021-10-12  5:41 ` [PATCH 0/2] ftrace: make sure preemption disabled on recursion testing 王贇
2021-10-13  3:16 ` [PATCH v2 0/2] fix & prevent the missing preemption disabling 王贇
2021-10-13  3:17   ` [PATCH v2 1/2] ftrace: disable preemption between ftrace_test_recursion_trylock/unlock() 王贇
2021-10-13  3:18   ` [PATCH v2 2/2] ftrace: do CPU checking after preemption disabled 王贇
2021-10-13  3:26   ` [PATCH v2 0/2] fix & prevent the missing preemption disabling Steven Rostedt
2021-10-13  3:33     ` 王贇
2021-10-26 23:48 ` [PATCH 0/2] ftrace: make sure preemption disabled on recursion testing Palmer Dabbelt

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