[PATCH v3 4/6] tracing: add trace_export support for trace_marker

Tingwei Zhang
2020-09-03T00:17:58Z

Add the support to route trace_marker buffer to other destination
via trace_export.

Signed-off-by: Tingwei Zhang <tingwei@codeaurora.org>
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
---
include/linux/trace.h | 1 +
kernel/trace/trace.c | 9 +++++++++
2 files changed, 10 insertions(+)

diff --git a/include/linux/trace.h b/include/linux/trace.h
index 5a01eeffb254..80b7df68bc0f 100644
--- a/include/linux/trace.h
+++ b/include/linux/trace.h
@@ -6,6 +6,7 @@

#define TRACE_EXPORT_FUNCTION BIT(0)
#define TRACE_EXPORT_EVENT BIT(1)
+#define TRACE_EXPORT_MARKER BIT(2)

/*
* The trace export - an export of Ftrace output. The trace_export
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 2f9302a8b322..67993abda394 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -271,6 +271,7 @@ static struct trace_export __rcu *ftrace_exports_list __read_mostly;

static DEFINE_STATIC_KEY_FALSE(trace_function_exports_enabled);
static DEFINE_STATIC_KEY_FALSE(trace_event_exports_enabled);
+static DEFINE_STATIC_KEY_FALSE(trace_marker_exports_enabled);

static inline void ftrace_exports_enable(struct trace_export *export)
{
@@ -279,6 +280,9 @@ static inline void ftrace_exports_enable(struct trace_export *export)

if (export->flags & TRACE_EXPORT_EVENT)
static_branch_inc(&trace_event_exports_enabled);
+
+ if (export->flags & TRACE_EXPORT_MARKER)
+ static_branch_inc(&trace_marker_exports_enabled);
}

static inline void ftrace_exports_disable(struct trace_export *export)
@@ -288,6 +292,9 @@ static inline void ftrace_exports_disable(struct trace_export *export)

if (export->flags & TRACE_EXPORT_EVENT)
static_branch_dec(&trace_event_exports_enabled);
+
+ if (export->flags & TRACE_EXPORT_MARKER)
+ static_branch_dec(&trace_marker_exports_enabled);
}

static void ftrace_exports(struct ring_buffer_event *event, int flag)
@@ -6648,6 +6655,8 @@ tracing_mark_write(struct file *filp, const char __user *ubuf,
} else
entry->buf[cnt] = '\0';

+ if (static_branch_unlikely(&trace_marker_exports_enabled))
+ ftrace_exports(event, TRACE_EXPORT_MARKER);
__buffer_unlock_commit(buffer, event);

if (tt)