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

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

From: Tzvetomir (VMware)  Stoyanov <tz.stoyanov@gmail.com>

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.

Signed-off-by: Tzvetomir (VMware)  Stoyanov <tz.stoyanov@gmail.com>
---
 include/tracefs.h | 2 ++
 tracefs-events.c  | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/include/tracefs.h b/include/tracefs.h
index 3358e33..ce8b09c 100644
--- a/include/tracefs.h
+++ b/include/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/tracefs-events.c b/tracefs-events.c
index ee45988..4431f77 100644
--- a/tracefs-events.c
+++ b/tracefs-events.c
@@ -117,6 +117,9 @@ 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
  *
@@ -127,6 +130,7 @@ 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 *),
@@ -167,6 +171,8 @@ 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))
-- 
2.28.0