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Date:   Fri,  9 Oct 2020 15:05:23 -0700
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Subject: [PATCH v3 1/2] tracing: support "bool" type in synthetic trace events
From:   Axel Rasmussen <axelrasmussen@google.com>
To:     Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Michel Lespinasse <walken@google.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        Laurent Dufour <ldufour@linux.ibm.com>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Jann Horn <jannh@google.com>,
        Chinwen Chang <chinwen.chang@mediatek.com>
Cc:     Yafang Shao <laoar.shao@gmail.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org
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Precedence: bulk

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

Acked-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Axel Rasmussen <axelrasmussen@google.com>
---
 kernel/trace/trace_events_synth.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/trace/trace_events_synth.c b/kernel/trace/trace_events_synth.c
index 8e1974fbad0e..8f94c84349a6 100644
--- a/kernel/trace/trace_events_synth.c
+++ b/kernel/trace/trace_events_synth.c
@@ -234,6 +234,8 @@ 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)
@@ -276,6 +278,8 @@ 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)
--
2.28.0.1011.ga647a8990f-goog