tracing: Clean up use of trace_create_maxlat_file()

In trace.c, the function trace_create_maxlat_file() is defined behind the
 #ifdef CONFIG_TRACER_MAX_TRACE block. The #else part defines it as:

 #define trace_create_maxlat_file(tr, d_tracer)				\
	trace_create_file("tracing_max_latency", TRACE_MODE_WRITE,	\
			  d_tracer, tr, &tracing_max_lat_fops)

But the one place that it it used has:

 #ifdef CONFIG_TRACER_MAX_TRACE
	trace_create_maxlat_file(tr, d_tracer);
 #endif

Which is pointless and also wrong!

It only gets created when both CONFIG_TRACE_MAX_TRACE and CONFIG_FS_NOTIFY
is defined, but the file itself should not be dependent on
CONFIG_FS_NOTIFY. Always create that file when TRACE_MAX_TRACE is defined
regardless if FS_NOTIFY is or is not.

Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://patch.msgid.link/20260207191101.0e014abd@robin
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 702ef851db453553744848c7af49dac0db177f48..d02c4004c718c6d21f3617eda0c0a0e521d4a264 100644 (file)
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -1912,10 +1912,7 @@ static ssize_t trace_seq_to_buffer(struct trace_seq *s, void *buf, size_t cnt)
 unsigned long __read_mostly    tracing_thresh;
 
 #ifdef CONFIG_TRACER_MAX_TRACE
-static const struct file_operations tracing_max_lat_fops;
-
 #ifdef LATENCY_FS_NOTIFY
-
 static struct workqueue_struct *fsnotify_wq;
 
 static void latency_fsnotify_workfn(struct work_struct *work)
@@ -1932,17 +1929,6 @@ static void latency_fsnotify_workfn_irq(struct irq_work *iwork)
        queue_work(fsnotify_wq, &tr->fsnotify_work);
 }
 
-static void trace_create_maxlat_file(struct trace_array *tr,
-                                    struct dentry *d_tracer)
-{
-       INIT_WORK(&tr->fsnotify_work, latency_fsnotify_workfn);
-       init_irq_work(&tr->fsnotify_irqwork, latency_fsnotify_workfn_irq);
-       tr->d_max_latency = trace_create_file("tracing_max_latency",
-                                             TRACE_MODE_WRITE,
-                                             d_tracer, tr,
-                                             &tracing_max_lat_fops);
-}
-
 __init static int latency_fsnotify_init(void)
 {
        fsnotify_wq = alloc_workqueue("tr_max_lat_wq",
@@ -1967,14 +1953,22 @@ void latency_fsnotify(struct trace_array *tr)
         */
        irq_work_queue(&tr->fsnotify_irqwork);
 }
+#endif /* !LATENCY_FS_NOTIFY */
 
-#else /* !LATENCY_FS_NOTIFY */
-
-#define trace_create_maxlat_file(tr, d_tracer)                         \
-       trace_create_file("tracing_max_latency", TRACE_MODE_WRITE,      \
-                         d_tracer, tr, &tracing_max_lat_fops)
+static const struct file_operations tracing_max_lat_fops;
 
+static void trace_create_maxlat_file(struct trace_array *tr,
+                                    struct dentry *d_tracer)
+{
+#ifdef LATENCY_FS_NOTIFY
+       INIT_WORK(&tr->fsnotify_work, latency_fsnotify_workfn);
+       init_irq_work(&tr->fsnotify_irqwork, latency_fsnotify_workfn_irq);
 #endif
+       tr->d_max_latency = trace_create_file("tracing_max_latency",
+                                             TRACE_MODE_WRITE,
+                                             d_tracer, tr,
+                                             &tracing_max_lat_fops);
+}
 
 /*
  * Copy the new maximum trace into the separate maximum-trace
@@ -2109,7 +2103,9 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu)
        __update_max_tr(tr, tsk, cpu);
        arch_spin_unlock(&tr->max_lock);
 }
-
+#else /* !CONFIG_TRACER_MAX_TRACE */
+static inline void trace_create_maxlat_file(struct trace_array *tr,
+                                           struct dentry *d_tracer) { }
 #endif /* CONFIG_TRACER_MAX_TRACE */
 
 struct pipe_wait {
@@ -10664,9 +10660,7 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer)
 
        create_trace_options_dir(tr);
 
-#ifdef CONFIG_TRACER_MAX_TRACE
        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");