[for-next][PATCH 3/7] tracing: Add "last_func_repeats" to struct trace_array

From: Steven Rostedt
Date: Fri Apr 16 2021 - 13:27:08 EST


From: "Yordan Karadzhov (VMware)" <y.karadz@xxxxxxxxx>

The field is used to keep track of the consecutive (on the same CPU) calls
of a single function. This information is needed in order to consolidate
the function tracing record in the cases when a single function is called
number of times.

Link: https://lkml.kernel.org/r/20210415181854.147448-4-y.karadz@xxxxxxxxx

Signed-off-by: Yordan Karadzhov (VMware) <y.karadz@xxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
kernel/trace/trace.c | 1 +
kernel/trace/trace.h | 12 ++++++++++++
2 files changed, 13 insertions(+)

diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 507a30bf26e4..82833be07c1e 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -9104,6 +9104,7 @@ static int __remove_instance(struct trace_array *tr)
ftrace_clear_pids(tr);
ftrace_destroy_function_files(tr);
tracefs_remove(tr->dir);
+ free_percpu(tr->last_func_repeats);
free_trace_buffers(tr);

for (i = 0; i < tr->nr_topts; i++) {
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 6a5b4c2a0fa7..a4f1b66049fd 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -262,6 +262,17 @@ struct cond_snapshot {
cond_update_fn_t update;
};

+/*
+ * struct trace_func_repeats - used to keep track of the consecutive
+ * (on the same CPU) calls of a single function.
+ */
+struct trace_func_repeats {
+ unsigned long ip;
+ unsigned long parent_ip;
+ unsigned long count;
+ u64 ts_last_call;
+};
+
/*
* The trace array - an array of per-CPU trace arrays. This is the
* highest level data structure that individual tracers deal with.
@@ -358,6 +369,7 @@ struct trace_array {
#ifdef CONFIG_TRACER_SNAPSHOT
struct cond_snapshot *cond_snapshot;
#endif
+ struct trace_func_repeats __percpu *last_func_repeats;
};

enum {
--
2.30.1