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SubjectRe: [PATCH] tracing: fix missing osnoise tracer on max_latency
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Hi, Steven.

在 2021/9/20 上午12:01, Steven Rostedt 写道:
> On Sat, 18 Sep 2021 13:11:18 +0800
> Jackie Liu <liu.yun@linux.dev> wrote:
>
>> From: Jackie Liu <liuyun01@kylinos.cn>
>>
>> The compiler warns when the data are actually unused:
>>
>> kernel/trace/trace.c:1712:13: error: ‘trace_create_maxlat_file’ defined but not used [-Werror=unused-function]
>> 1712 | static void trace_create_maxlat_file(struct trace_array *tr,
>> | ^~~~~~~~~~~~~~~~~~~~~~~~
>>
>> [Why]
>> CONFIG_HWLAT_TRACER=n, CONFIG_TRACER_MAX_TRACE=n, CONFIG_OSNOISE_TRACER=y
>> gcc report warns.
>>
>> [How]
>> Now trace_create_maxlat_file will only take effect when
>> CONFIG_HWLAT_TRACER=y or CONFIG_TRACER_MAX_TRACE=y. In fact, after
>> adding osnoise trace, it also needs to take effect.
>>
>> BTW, Fixed the conflicting defined comment information.
>
> Thanks for the report.
>
>>
>> Fixes: bce29ac9ce0b ("trace: Add osnoise tracer")
>> Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
>> Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
>> ---
>> kernel/trace/trace.c | 9 +++------
>> 1 file changed, 3 insertions(+), 6 deletions(-)
>>
>> diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
>> index 7896d30d90f7..d7e3ed82fafd 100644
>> --- a/kernel/trace/trace.c
>> +++ b/kernel/trace/trace.c
>> @@ -1744,11 +1744,7 @@ void latency_fsnotify(struct trace_array *tr)
>> irq_work_queue(&tr->fsnotify_irqwork);
>> }
>>
>> -/*
>> - * (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)) && \
>> - * defined(CONFIG_FSNOTIFY)
>> - */
>> -#else
>> +#else /* LATENCY_FS_NOTIFY >>
>> #define trace_create_maxlat_file(tr, d_tracer) \
>> trace_create_file("tracing_max_latency", 0644, d_tracer, \
>
> To clean this up even better, we should add here:
>
> #elif defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
> || defined(CONFIG_OSNOISE_TRACER)

This place should need to use LATENCY_FS_NOTIFY, because not only these
three Traces, we also need to pay attention to CONFIG_FSNOTIFY, at
least, we should not change the original meaning.

How about this:

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7896d30d90f7..6a88d03c6d3b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1744,16 +1744,14 @@ void latency_fsnotify(struct trace_array *tr)
irq_work_queue(&tr->fsnotify_irqwork);
}

-/*
- * (defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)) && \
- * defined(CONFIG_FSNOTIFY)
- */
-#else
+#elif defined(LATENCY_FS_NOTIFY)

#define trace_create_maxlat_file(tr, d_tracer) \
trace_create_file("tracing_max_latency", 0644, d_tracer, \
&tr->max_latency, &tracing_max_lat_fops)

+#else
+#define trace_create_maxlat_file(tr, d_tracer) do { } while (0)
#endif

#ifdef CONFIG_TRACER_MAX_TRACE
@@ -9473,9 +9471,7 @@ init_tracer_tracefs(struct trace_array *tr, struct
dentry *d_tracer)

create_trace_options_dir(tr);

-#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
trace_create_maxlat_file(tr, d_tracer);
-#endif

if (ftrace_create_function_files(tr, d_tracer))
MEM_FAIL(1, "Could not allocate function filter files");

==
What do you think? If there is no problem, I will send V2.

--
BR.
Jackie Liu

>
> # define trace_create_maxlat_file(tr, d_tracer) \
> trace_create_file("tracing_max_latency", 0644, d_tracer, \
> &tr->max_latency, &tracing_max_lat_fops)
>
> #else
> # define trace_create_maxlat_file(tr, d_tracer) do { } while (0)
> #endif
>
>> @@ -9473,7 +9469,8 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
>>
>> create_trace_options_dir(tr);
>>
>> -#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER)
>> +#if defined(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
>> + || defined(CONFIG_OSNOISE_TRACER)
>
> And remove the #if statement complete from inside the function.
>
> -- Steve
>
>> trace_create_maxlat_file(tr, d_tracer);
>> #endif
>>
>

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