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
>
next prev parent 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
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