2 files changed, 65 insertions, 18 deletions

diff --git a/Documentation/trace-cmd-report.1.txt b/Documentation/trace-cmd-report.1.txt
index fbab3f4..86169f2 100644
--- a/Documentation/trace-cmd-report.1.txt
+++ b/Documentation/trace-cmd-report.1.txt
@@ -98,6 +98,14 @@ OPTIONS
 
     Although the output displays 'R', having 'prev_stat=="R"' will not work.
 
+    Note: You can also specify 'COMM' as an EVENT_FIELD. This will use the
+    task name (or comm) of the record to compare. For example, to filter out
+    all of the "trace-cmd" tasks:
+
+------------------------------------------
+    -F '.*:COMM != "trace-cmd"'
+------------------------------------------
+
 *-v*::
     This causes the following filters of *-F* to filter out the matching
     events.
diff --git a/parse-filter.c b/parse-filter.c
index 75512e3..eb2ef6d 100644
--- a/parse-filter.c
+++ b/parse-filter.c
@@ -28,6 +28,12 @@
 #include "parse-events.h"
 #include "util.h"
 
+#define COMM "COMM"
+
+static struct format_field comm = {
+        .name = "COMM",
+};
+
 struct event_list {
         struct event_list       *next;
         struct event_format     *event;
@@ -539,13 +545,18 @@ process_value_token(struct event_format *event, struct filter_arg **parg,
                 }
                 /* Consider this a field */
                 field = pevent_find_any_field(event, token);
-                free_token(token);
                 if (!field) {
-                        /* not a field, so NULL it up */
-                        free_arg(arg);
-                        arg = NULL;
-                        break;
+                        if (strcmp(token, COMM) != 0) {
+                                /* not a field, so NULL it up */
+                                free_token(token);
+                                free_arg(arg);
+                                arg = NULL;
+                                break;
+                        }
+                        /* If token is 'COMM' then it is special */
+                        field = &comm;
                 }
+                free_token(token);
 
                 arg->type = FILTER_ARG_FIELD;
                 arg->field.field = field;
@@ -1414,11 +1425,31 @@ int pevent_filter_event_has_trivial(struct event_filter *filter,
 static int test_filter(struct event_format *event,
                        struct filter_arg *arg, struct record *record);
 
+static const char *
+get_comm(struct event_format *event, struct record *record)
+{
+        const char *comm;
+        int pid;
+
+        pid = pevent_data_pid(event->pevent, record);
+        comm = pevent_data_comm_from_pid(event->pevent, pid);
+        return comm;
+}
+
 static unsigned long long
-get_value(struct format_field *field, struct record *record)
+get_value(struct event_format *event,
+          struct format_field *field, struct record *record)
 {
         unsigned long long val;
 
+        /* Handle our dummy "comm" field */
+        if (field == &comm) {
+                const char *name;
+
+                name = get_comm(event, record);
+                return (unsigned long long)name;
+        }
+
         pevent_read_number_field(field, record->data, &val);
 
         if (!(field->flags & FIELD_IS_SIGNED))
@@ -1491,7 +1522,7 @@ get_arg_value(struct event_format *event, struct filter_arg *arg, struct record
 {
         switch (arg->type) {
         case FILTER_ARG_FIELD:
-                return get_value(arg->field.field, record);
+                return get_value(event, arg->field.field, record);
 
         case FILTER_ARG_VALUE:
                 if (arg->value.type != FILTER_NUMBER)
@@ -1540,11 +1571,9 @@ static int test_num(struct event_format *event,
         }
 }
 
-static int test_str(struct event_format *event,
-                    struct filter_arg *arg, struct record *record)
+static const char *get_field_str(struct filter_arg *arg, struct record *record)
 {
         const char *val = record->data + arg->str.field->offset;
-        const char *buffer;
 
         /*
          * We need to copy the data since we can't be sure the field
@@ -1554,24 +1583,34 @@ static int test_str(struct event_format *event,
                 /* copy it */
                 memcpy(arg->str.buffer, val, arg->str.field->size);
                 /* the buffer is already NULL terminated */
-                buffer = arg->str.buffer;
-        } else
-                /* OK, it's NULL terminated */
-                buffer = val;
+                val = arg->str.buffer;
+        }
+        return val;
+}
+
+static int test_str(struct event_format *event,
+                    struct filter_arg *arg, struct record *record)
+{
+        const char *val;
+
+        if (arg->str.field == &comm)
+                val = get_comm(event, record);
+        else
+                val = get_field_str(arg, record);
 
         switch (arg->str.type) {
         case FILTER_CMP_MATCH:
-                return strcmp(buffer, arg->str.val) == 0;
+                return strcmp(val, arg->str.val) == 0;
 
         case FILTER_CMP_NOT_MATCH:
-                return strcmp(buffer, arg->str.val) != 0;
+                return strcmp(val, arg->str.val) != 0;
 
         case FILTER_CMP_REGEX:
                 /* Returns zero on match */
-                return !regexec(&arg->str.reg, buffer, 0, NULL, 0);
+                return !regexec(&arg->str.reg, val, 0, NULL, 0);
 
         case FILTER_CMP_NOT_REGEX:
-                return regexec(&arg->str.reg, buffer, 0, NULL, 0);
+                return regexec(&arg->str.reg, val, 0, NULL, 0);
 
         default:
                 /* ?? */