live-patching.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: 王贇 <yun.wang@linux.alibaba.com>
To: Miroslav Benes <mbenes@suse.cz>
Cc: Guo Ren <guoren@kernel.org>, Steven Rostedt <rostedt@goodmis.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>, 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 v3 1/2] ftrace: disable preemption between ftrace_test_recursion_trylock/unlock()
Date: Thu, 14 Oct 2021 17:22:43 +0800	[thread overview]
Message-ID: <d293a0d2-9864-3f92-a333-e29d919d5a02@linux.alibaba.com> (raw)
In-Reply-To: <alpine.LSU.2.21.2110141108150.23710@pobox.suse.cz>



On 2021/10/14 下午5:13, Miroslav Benes wrote:
>> diff --git a/kernel/livepatch/patch.c b/kernel/livepatch/patch.c
>> index e8029ae..b8d75fb 100644
>> --- a/kernel/livepatch/patch.c
>> +++ b/kernel/livepatch/patch.c
>> @@ -49,14 +49,16 @@ static void notrace klp_ftrace_handler(unsigned long ip,
>>
>>  	ops = container_of(fops, struct klp_ops, fops);
>>
>> +	/*
>> +	 *
> 
> This empty line is not useful.
> 
>> +	 * The ftrace_test_recursion_trylock() will disable preemption,
>> +	 * which is required for the variant of synchronize_rcu() that is
>> +	 * used to allow patching functions where RCU is not watching.
>> +	 * See klp_synchronize_transition() for more details.
>> +	 */
>>  	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().
>> -	 */
>> -	preempt_disable_notrace();
>>
>>  	func = list_first_or_null_rcu(&ops->func_stack, struct klp_func,
>>  				      stack_node);
>> @@ -120,7 +122,6 @@ static void notrace klp_ftrace_handler(unsigned long ip,
>>  	klp_arch_set_pc(fregs, (unsigned long)func->new_func);
>>
>>  unlock:
>> -	preempt_enable_notrace();
>>  	ftrace_test_recursion_unlock(bit);
>>  }
> 
> Acked-by: Miroslav Benes <mbenes@suse.cz>
> 
> for the livepatch part of the patch.
> 
> I would also ask you not to submit new versions so often, so that the 
> other reviewers have time to actually review the patch set.
> 
> Quoting from Documentation/process/submitting-patches.rst:
> 
> "Wait for a minimum of one week before resubmitting or pinging reviewers - 
> possibly longer during busy times like merge windows."

Thanks for the Ack and suggestion, will take care from now on :-)

Regards,
Michael Wang

> 
> Thanks
> 
> Miroslav
> 

  reply	other threads:[~2021-10-14  9:22 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-13  8:51 [PATCH v3 0/2] fix & prevent the missing preemption disabling 王贇
2021-10-13  8:51 ` [PATCH v3 1/2] ftrace: disable preemption between ftrace_test_recursion_trylock/unlock() 王贇
2021-10-14  9:13   ` Miroslav Benes
2021-10-14  9:22     ` 王贇 [this message]
2021-10-14 13:28     ` Steven Rostedt
2021-10-14 15:14   ` Petr Mladek
2021-10-15  3:13     ` 王贇
2021-10-15  4:45       ` 王贇
2021-10-15  7:28       ` Petr Mladek
2021-10-15  9:12         ` 王贇
2021-10-15 13:35           ` Steven Rostedt
2021-10-15  3:39     ` Steven Rostedt
2021-10-13  8:52 ` [PATCH v3 2/2] ftrace: do CPU checking after preemption disabled 王贇

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=d293a0d2-9864-3f92-a333-e29d919d5a02@linux.alibaba.com \
    --to=yun.wang@linux.alibaba.com \
    --cc=James.Bottomley@HansenPartnership.com \
    --cc=aou@eecs.berkeley.edu \
    --cc=benh@kernel.crashing.org \
    --cc=bp@alien8.de \
    --cc=colin.king@canonical.com \
    --cc=deller@gmx.de \
    --cc=guoren@kernel.org \
    --cc=hpa@zytor.com \
    --cc=jikos@kernel.org \
    --cc=joe.lawrence@redhat.com \
    --cc=jpoimboe@redhat.com \
    --cc=jszhang@kernel.org \
    --cc=linux-csky@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-parisc@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=linuxppc-dev@lists.ozlabs.org \
    --cc=live-patching@vger.kernel.org \
    --cc=mbenes@suse.cz \
    --cc=mhiramat@kernel.org \
    --cc=mingo@redhat.com \
    --cc=mpe@ellerman.id.au \
    --cc=npiggin@gmail.com \
    --cc=palmer@dabbelt.com \
    --cc=paul.walmsley@sifive.com \
    --cc=paulus@samba.org \
    --cc=peterz@infradead.org \
    --cc=pmladek@suse.com \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).