tracing: support "bool" type in synthetic trace events

It's common [1] to define tracepoint fields as "bool" when they contain
a true / false value. Currently, defining a synthetic event with a
"bool" field yields EINVAL. It's possible to work around this by using
e.g. u8 (assuming sizeof(bool) is 1, and bool is unsigned; if either of
these properties don't match, you get EINVAL [2]).

Supporting "bool" explicitly makes hooking this up easier and more
portable for userspace.

[1]: grep -r "bool" include/trace/events/
[2]: check_synth_field() in kernel/trace/trace_events_hist.c

Link: https://lkml.kernel.org/r/20201009220524.485102-2-axelrasmussen@google.com
Acked-by: Michel Lespinasse <walken@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index d239f0e2af8f4d200bdb3c936858de1bf560da47..3212e2c653b35c1eac5a20d496f319465adff124 100644 (file)
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -229,6 +229,8 @@ static int synth_field_size(char *type)
                size = sizeof(long);
        else if (strcmp(type, "unsigned long") == 0)
                size = sizeof(unsigned long);
+       else if (strcmp(type, "bool") == 0)
+               size = sizeof(bool);
        else if (strcmp(type, "pid_t") == 0)
                size = sizeof(pid_t);
        else if (strcmp(type, "gfp_t") == 0)
@@ -271,6 +273,8 @@ static const char *synth_field_fmt(char *type)
                fmt = "%ld";
        else if (strcmp(type, "unsigned long") == 0)
                fmt = "%lu";
+       else if (strcmp(type, "bool") == 0)
+               fmt = "%d";
        else if (strcmp(type, "pid_t") == 0)
                fmt = "%d";
        else if (strcmp(type, "gfp_t") == 0)