[PATCH 5/9] libtracefs: Extend tracefs_iterate_raw_events() to iterate per CPU

[Steven Rostedt <rostedt@xxxxxxxxxxx>]

From: "Tzvetomir (VMware) Stoyanov" <tz.stoyanov@xxxxxxxxx>

There are some use cases where only raw events from particular CPUs
should be iterated. An additional parameter is added to this API which
allows only trace buffers for specified CPUs to be iterated.

Link: https://lore.kernel.org/linux-trace-devel/20201204084739.555327-1-tz.stoyanov@xxxxxxxxx

Signed-off-by: Tzvetomir (VMware)  Stoyanov <tz.stoyanov@xxxxxxxxx>
[ Ported to work with trace-cmd ]
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
---
 include/tracefs/tracefs.h    | 2 ++
 lib/tracefs/tracefs-events.c | 6 ++++++
 tracecmd/trace-record.c      | 2 +-
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/tracefs/tracefs.h b/include/tracefs/tracefs.h
index 3358e33d9f11..ce8b09ca5bd0 100644
--- a/include/tracefs/tracefs.h
+++ b/include/tracefs/tracefs.h
@@ -6,6 +6,7 @@
 #ifndef _TRACE_FS_H
 #define _TRACE_FS_H
 
+#include <sched.h>
 #include "traceevent/event-parse.h"
 
 char *tracefs_get_tracing_file(const char *name);
@@ -44,6 +45,7 @@ char **tracefs_event_systems(const char *tracing_dir);
 char **tracefs_system_events(const char *tracing_dir, const char *system);
 int tracefs_iterate_raw_events(struct tep_handle *tep,
 				struct tracefs_instance *instance,
+				cpu_set_t *cpus, int cpu_size,
 				int (*callback)(struct tep_event *,
 						struct tep_record *,
 						int, void *),
diff --git a/lib/tracefs/tracefs-events.c b/lib/tracefs/tracefs-events.c
index a4e5215f8971..ba640a9e162c 100644
--- a/lib/tracefs/tracefs-events.c
+++ b/lib/tracefs/tracefs-events.c
@@ -116,6 +116,9 @@ get_events_in_page(struct tep_handle *tep, void *page,
  *				per CPU trace buffers
  * @tep: a handle to the trace event parser context
  * @instance: ftrace instance, can be NULL for the top instance
+ * @cpus: Iterate only through the buffers of CPUs, set in the mask.
+ *	  If NULL, iterate through all CPUs.
+ * @cpu_size: size of @cpus set
  * @callback: A user function, called for each record from the file
  * @callback_context: A custom context, passed to the user callback function
  *
@@ -126,6 +129,7 @@ get_events_in_page(struct tep_handle *tep, void *page,
  */
 int tracefs_iterate_raw_events(struct tep_handle *tep,
 				struct tracefs_instance *instance,
+				cpu_set_t *cpus, int cpu_size,
 				int (*callback)(struct tep_event *,
 						struct tep_record *,
 						int, void *),
@@ -166,6 +170,8 @@ int tracefs_iterate_raw_events(struct tep_handle *tep,
 		if (strlen(name) < 4 || strncmp(name, "cpu", 3) != 0)
 			continue;
 		cpu = atoi(name + 3);
+		if (cpus && !CPU_ISSET_S(cpu, cpu_size, cpus))
+			continue;
 		sprintf(file, "%s/%s", path, name);
 		ret = stat(file, &st);
 		if (ret < 0 || !S_ISDIR(st.st_mode))
diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index 3a63f1bdda97..f8baed7dcd47 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -4585,7 +4585,7 @@ static unsigned long long find_time_stamp(struct tep_handle *tep)
 {
 	unsigned long long ts = 0;
 
-	if (!tracefs_iterate_raw_events(tep, NULL, find_ts, &ts))
+	if (!tracefs_iterate_raw_events(tep, NULL, NULL, 0, find_ts, &ts))
 		return ts;
 
 	return 0;
-- 
2.29.2