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-rw-r--r--Documentation/trace/histogram.rst2
-rw-r--r--kernel/trace/trace.c4
-rw-r--r--kernel/trace/trace_events_hist.c22
3 files changed, 21 insertions, 7 deletions
diff --git a/Documentation/trace/histogram.rst b/Documentation/trace/histogram.rst
index b71e09f745c3..f99be8062bc8 100644
--- a/Documentation/trace/histogram.rst
+++ b/Documentation/trace/histogram.rst
@@ -191,7 +191,7 @@ Documentation written by Tom Zanussi
with the event, in nanoseconds. May be
modified by .usecs to have timestamps
interpreted as microseconds.
- cpu int the cpu on which the event occurred.
+ common_cpu int the cpu on which the event occurred.
====================== ==== =======================================
Extended error information
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index f8b80b5bab71..c59dd35a6da5 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -5609,6 +5609,10 @@ static const char readme_msg[] =
"\t [:name=histname1]\n"
"\t [:<handler>.<action>]\n"
"\t [if <filter>]\n\n"
+ "\t Note, special fields can be used as well:\n"
+ "\t common_timestamp - to record current timestamp\n"
+ "\t common_cpu - to record the CPU the event happened on\n"
+ "\n"
"\t When a matching event is hit, an entry is added to a hash\n"
"\t table using the key(s) and value(s) named, and the value of a\n"
"\t sum called 'hitcount' is incremented. Keys and values\n"
diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 16a9dfc9fffc..34325f41ebc0 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1111,7 +1111,7 @@ static const char *hist_field_name(struct hist_field *field,
field->flags & HIST_FIELD_FL_ALIAS)
field_name = hist_field_name(field->operands[0], ++level);
else if (field->flags & HIST_FIELD_FL_CPU)
- field_name = "cpu";
+ field_name = "common_cpu";
else if (field->flags & HIST_FIELD_FL_EXPR ||
field->flags & HIST_FIELD_FL_VAR_REF) {
if (field->system) {
@@ -1991,14 +1991,24 @@ parse_field(struct hist_trigger_data *hist_data, struct trace_event_file *file,
hist_data->enable_timestamps = true;
if (*flags & HIST_FIELD_FL_TIMESTAMP_USECS)
hist_data->attrs->ts_in_usecs = true;
- } else if (strcmp(field_name, "cpu") == 0)
+ } else if (strcmp(field_name, "common_cpu") == 0)
*flags |= HIST_FIELD_FL_CPU;
else {
field = trace_find_event_field(file->event_call, field_name);
if (!field || !field->size) {
- hist_err(tr, HIST_ERR_FIELD_NOT_FOUND, errpos(field_name));
- field = ERR_PTR(-EINVAL);
- goto out;
+ /*
+ * For backward compatibility, if field_name
+ * was "cpu", then we treat this the same as
+ * common_cpu.
+ */
+ if (strcmp(field_name, "cpu") == 0) {
+ *flags |= HIST_FIELD_FL_CPU;
+ } else {
+ hist_err(tr, HIST_ERR_FIELD_NOT_FOUND,
+ errpos(field_name));
+ field = ERR_PTR(-EINVAL);
+ goto out;
+ }
}
}
out:
@@ -5085,7 +5095,7 @@ static void hist_field_print(struct seq_file *m, struct hist_field *hist_field)
seq_printf(m, "%s=", hist_field->var.name);
if (hist_field->flags & HIST_FIELD_FL_CPU)
- seq_puts(m, "cpu");
+ seq_puts(m, "common_cpu");
else if (field_name) {
if (hist_field->flags & HIST_FIELD_FL_VAR_REF ||
hist_field->flags & HIST_FIELD_FL_ALIAS)