Re: [PATCH] ftrace: Replace ftrace_disabled variable with ftrace_is_dead function

["Bang Li" <libang.li@antgroup.com>]

On 2024/4/20 9:40, Steven Rostedt wrote:
> On Fri, 19 Apr 2024 22:38:44 +0800
> "Bang Li" <libang.li@antgroup.com> wrote:
> 
>> Use the existing function ftrace_is_dead to replace the variable to make
>> the code clearer.
>>
>> Signed-off-by: Bang Li <libang.li@antgroup.com>
>> ---
>>   kernel/trace/ftrace.c | 46 +++++++++++++++++++++----------------------
>>   1 file changed, 23 insertions(+), 23 deletions(-)
>>
>> diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
>> index 50ca4d4f8840..4a08c79db677 100644
>> --- a/kernel/trace/ftrace.c
>> +++ b/kernel/trace/ftrace.c
>> @@ -2693,7 +2693,7 @@ void __weak ftrace_replace_code(int mod_flags)
>>   	int schedulable = mod_flags & FTRACE_MODIFY_MAY_SLEEP_FL;
>>   	int failed;
>>   
>> -	if (unlikely(ftrace_disabled))
>> +	if (unlikely(ftrace_is_dead()))
>>   		return;
>>   
> 
> NACK!
> 
> ftrace_is_dead() is only there to make the static variable
> "ftrace_disabled" available for code outside of ftrace.c. In ftrace.c,
> it is perfectly fine to use ftrace_disabled.
> 
> -- Steve

Thank you for your explanation, let me understand this. How about
replacing ftrace_disabled with unlike(ftrace_disabled)?

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 50ca4d4f8840..76e0814723cb 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -6767,7 +6767,7 @@ void ftrace_release_mod(struct module *mod)

         mutex_lock(&ftrace_lock);

-       if (ftrace_disabled)
+       if (unlikely(ftrace_disabled))
                 goto out_unlock;

         list_for_each_entry_safe(mod_map, n, &ftrace_mod_maps, list) {
@@ -6830,7 +6830,7 @@ void ftrace_module_enable(struct module *mod)

         mutex_lock(&ftrace_lock);

-       if (ftrace_disabled)
+       if (unlikely(ftrace_disabled))
                 goto out_unlock;

         /*

Thanks again for the review!
Bang