tracing: Fix missing osnoise tracer on max_latency

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.

Link: https://lore.kernel.org/all/c1d9e328-ad7c-920b-6c24-9e1598a6421c@infradead.org/
Link: https://lkml.kernel.org/r/20210922025122.3268022-1-liu.yun@linux.dev
Fixes: bce29ac9ce0b ("trace: Add osnoise tracer")
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Signed-off-by: Jackie Liu <liuyun01@kylinos.cn>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 7896d30..bc677cd 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1744,16 +1744,15 @@ 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(CONFIG_TRACER_MAX_TRACE) || defined(CONFIG_HWLAT_TRACER) \
+       || defined(CONFIG_OSNOISE_TRACER)
 
 #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 +9472,7 @@ 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");