trace-cmd split: Save missed events

Commit Message

Steven Rostedt June 8, 2022, 3:14 p.m. UTC

From: "Steven Rostedt (Google)" <[e-mail]>

If the file that is being split has missed events, the new file does not
create them. This gets confusing for users that see gaps in the trace.

Have the split code preserve the missed events in the new file.

Reported-by: Johannes Berg <[e-mail]>
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=212421
Signed-off-by: Steven Rostedt (Google) <[e-mail]>
---
 tracecmd/trace-split.c | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

Patch

diff --git a/tracecmd/trace-split.c b/tracecmd/trace-split.c
index 83c5402c279b..851ec94eda1f 100644
--- a/tracecmd/trace-split.c
+++ b/tracecmd/trace-split.c
@@ -40,6 +40,7 @@  enum split_types {
 struct cpu_data {
 	unsigned long long		ts;
 	unsigned long long		offset;
+	unsigned long long		missed_events;
 	struct tep_record		*record;
 	int				cpu;
 	int				fd;
@@ -137,18 +138,37 @@  static int write_record(struct tracecmd_input *handle,
 	return 1;
 }
 
+#define MISSING_EVENTS (1UL << 31)
+#define MISSING_STORED (1UL << 30)
+
+#define COMMIT_MASK ((1 << 27) - 1)
+
 static void write_page(struct tep_handle *pevent,
 		       struct cpu_data *cpu_data, int long_size)
 {
+	unsigned long long *ptr = NULL;
+	unsigned int flags = 0;
+
+	if (cpu_data->missed_events) {
+		flags |= MISSING_EVENTS;
+		if (cpu_data->missed_events > 0) {
+			flags |= MISSING_STORED;
+			ptr = cpu_data->page + cpu_data->index;
+		}
+	}
+
 	if (long_size == 8) {
-		unsigned long long index = cpu_data->index - 16;
+		unsigned long long index = cpu_data->index - 16 + flags;;
 		*(unsigned long long *)cpu_data->commit =
 				tep_read_number(pevent, &index, 8);
 	} else {
-		unsigned int index = cpu_data->index - 12;
+		unsigned int index = cpu_data->index - 12 + flags;;
 		*(unsigned int *)cpu_data->commit =
 			tep_read_number(pevent, &index, 4);
 	}
+	if (ptr)
+		*ptr = tep_read_number(pevent, &cpu_data->missed_events, 8);
+
 	write(cpu_data->fd, cpu_data->page, page_size);
 }
 
@@ -224,7 +244,8 @@  static int parse_cpu(struct tracecmd_input *handle,
 		start = record->ts;
 
 	while (record && (!end || record->ts <= end)) {
-		if (cpu_data[cpu].index + record->record_size > page_size) {
+		if ((cpu_data[cpu].index + record->record_size > page_size) ||
+		    record->missed_events) {
 
 			if (type == SPLIT_PAGES && ++pages > count_limit)
 				break;
@@ -237,6 +258,8 @@  static int parse_cpu(struct tracecmd_input *handle,
 					die("Failed to allocate page");
 			}
 
+			cpu_data[cpu].missed_events = record->missed_events;
+
 			memset(cpu_data[cpu].page, 0, page_size);
 			ptr = cpu_data[cpu].page;