[PATCH v3 1/2] ftrace: disable preemption between ftrace_test_recursion_trylock/unlock()
yun.wang at linux.alibaba.com
Thu Oct 14 02:22:43 PDT 2021
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))
>> - /*
>> - * 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,
>> @@ -120,7 +122,6 @@ static void notrace klp_ftrace_handler(unsigned long ip,
>> klp_arch_set_pc(fregs, (unsigned long)func->new_func);
>> - preempt_enable_notrace();
> Acked-by: Miroslav Benes <mbenes at 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 :-)
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