1 files changed, 62 insertions, 2 deletions

diff --git a/trace-cmd.c b/trace-cmd.c
index 6c3d91c..4466f93 100644
--- a/trace-cmd.c
+++ b/trace-cmd.c
@@ -283,7 +283,7 @@ static void update_ftrace_pid(const char *pid)
         close(fd);
 }
 
-static void update_pid_event_filters(char *pid);
+static void update_pid_event_filters(const char *pid);
 static void enable_tracing(void);
 
 static void update_task_filter(void)
@@ -720,7 +720,60 @@ static void disable_all(void)
         clear_trace();
 }
 
-static void update_pid_event_filters(char *pid)
+static void update_filter(const char *event_name, const char *field,
+                          const char *pid)
+{
+        char buf[BUFSIZ];
+        char *filter_name;
+        char *path;
+        char *filter;
+        int fd;
+        int ret;
+
+        filter_name = malloc_or_die(strlen(event_name) +
+                                    strlen("events//filter") + 1);
+        sprintf(filter_name, "events/%s/filter", event_name);
+
+        path = get_tracing_file(filter_name);
+        free(filter_name);
+
+        /* Ignore if file does not exist */
+        fd = open(path, O_RDONLY);
+        if (fd < 0)
+                goto out;
+
+        ret = read(fd, buf, BUFSIZ);
+        if (ret < 0)
+                die("Can't read %s", path);
+        close(fd);
+
+        /* append unless there is currently no filter */
+        if (strcmp(buf, "none") == 0) {
+                filter = malloc_or_die(strlen(pid) + strlen(field) +
+                                       strlen("(==)") + 1);
+                sprintf(filter, "(%s==%s)", field, pid);
+        } else {
+                filter = malloc_or_die(strlen(pid) + strlen(field) +
+                                       strlen(buf) + strlen("()||(==)") + 1);
+                sprintf(filter, "(%s)||(%s==%s)", buf, field, pid);
+        }
+
+        fd = open(path, O_WRONLY);
+        if (fd < 0)
+                die("can't open %s", path);
+
+        ret = write(fd, filter, strlen(filter));
+        if (ret < 0)
+                die("Can't write to %s", path);
+        close(fd);
+
+        free(filter);
+
+ out:
+        put_tracing_file(path);
+}
+
+static void update_pid_event_filters(const char *pid)
 {
         struct event_list *event;
         char *filter;
@@ -745,6 +798,13 @@ static void update_pid_event_filters(char *pid)
         }
 
         free(filter);
+
+        /*
+         * Also make sure that the sched_switch to this pid
+         * and wakeups of this pid are also traced.
+         */
+        update_filter("sched/sched_switch", "next_pid", pid);
+        update_filter("sched/sched_wakeup", "pid", pid);
 }
 
 static void enable_events(void)