From: "Steven Rostedt (Google)" <rostedt@xxxxxxxxxxx>
I've hit a few bugs using libtraceeval because of a common cut and paste
error. To assign keys, the following is common to do:
TRACEEVAL_SET_STRING(keys[0], "string");
TRACEEVAL_SET_NUMBER(keys[0], 123);
But the above has a bug! The second entry was supposed to be keys[1], and
not keys[0]. This bug had me scratching my head a few times until I found
it. The failure is that passing keys to traceeval_insert() or something
similar, the traceeval_insert() will fail because it's expecting keys[0]
to be a string, but the above converted it to a number.
Help prevent this by passing a string into one of the NUMBER() macros or a
number in the STRING() macro fail to build. It doesn't prevent all
combinations as it is common to pass various size to NUMBER() for example:
unsigned long long val;
TRACEEVAL_SET_NUMBER_16(keys[0], val);
The above is allowed, but a string should never go into a number and vice
versa. Catching that should find some bugs at build.
Nothing is done with TRACEEVAL_SET_POINTER() as pointers are totally the
responsibility of the developer.
This also requires that you can not just pass a void pointer to one of the
STRING() macros and it requires a typecast now (as the samples had to be
updated).
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
Changes since v1: https://lore.kernel.org/linux-trace-devel/20231006131647.0bae5a20@xxxxxxxxxxxxxxxxxx
- Rebased to updated wake-lat.c example.
include/traceeval.h | 28 +++++++++++++++++++++-------
samples/wake-lat.c | 4 +++-
2 files changed, 24 insertions(+), 8 deletions(-)
diff --git a/include/traceeval.h b/include/traceeval.h
index d8095ba5c1a1..5464a5a55fe4 100644
--- a/include/traceeval.h
+++ b/include/traceeval.h
@@ -97,13 +97,27 @@ struct traceeval_data {
(data).member = (val); \
} while (0)
-#define TRACEEVAL_SET_NUMBER(data, val) __TRACEEVAL_SET(data, NUMBER, number, val)
-#define TRACEEVAL_SET_NUMBER_8(data, val) __TRACEEVAL_SET(data, NUMBER_8, number_8, val)
-#define TRACEEVAL_SET_NUMBER_16(data, val) __TRACEEVAL_SET(data, NUMBER_16, number_16, val)
-#define TRACEEVAL_SET_NUMBER_32(data, val) __TRACEEVAL_SET(data, NUMBER_32, number_32, val)
-#define TRACEEVAL_SET_NUMBER_64(data, val) __TRACEEVAL_SET(data, NUMBER_64, number_64, val)
-#define TRACEEVAL_SET_STRING(data, val) __TRACEEVAL_SET(data, STRING, string, val)
-#define TRACEEVAL_SET_CSTRING(data, val) __TRACEEVAL_SET(data, STRING, cstring, val)
+/* Have strings and pointers fail to be set to numbers */
+#define __TRACEEVAL_SET_NUM(data, data_type, member, val) \
+ do { \
+ char *__test__[val] __attribute__((unused)); \
+ __TRACEEVAL_SET(data, data_type, member, val); \
+ } while (0)
+
+/* Have numbers fail to be assigned as strings */
+#define __TRACEEVAL_SET_STR(data, data_type, member, val) \
+ do { \
+ char __test__ __attribute__((unused)) = (val)[0]; \
+ __TRACEEVAL_SET(data, data_type, member, val); \
+ } while (0)
+
+#define TRACEEVAL_SET_NUMBER(data, val) __TRACEEVAL_SET_NUM(data, NUMBER, number, val)
+#define TRACEEVAL_SET_NUMBER_8(data, val) __TRACEEVAL_SET_NUM(data, NUMBER_8, number_8, val)
+#define TRACEEVAL_SET_NUMBER_16(data, val) __TRACEEVAL_SET_NUM(data, NUMBER_16, number_16, val)
+#define TRACEEVAL_SET_NUMBER_32(data, val) __TRACEEVAL_SET_NUM(data, NUMBER_32, number_32, val)
+#define TRACEEVAL_SET_NUMBER_64(data, val) __TRACEEVAL_SET_NUM(data, NUMBER_64, number_64, val)
+#define TRACEEVAL_SET_STRING(data, val) __TRACEEVAL_SET_STR(data, STRING, string, val)
+#define TRACEEVAL_SET_CSTRING(data, val) __TRACEEVAL_SET_STR(data, STRING, cstring, val)
#define TRACEEVAL_SET_POINTER(data, val) __TRACEEVAL_SET(data, POINTER, pointer, val)
struct traceeval_type;
diff --git a/samples/wake-lat.c b/samples/wake-lat.c
index 086f67d8fe49..163815997793 100644
--- a/samples/wake-lat.c
+++ b/samples/wake-lat.c
@@ -84,6 +84,7 @@ static int sched_callback(struct tracecmd_input *handle, struct tep_event *event
struct traceeval_data keys[2];
struct traceeval_data vals[2];
const struct traceeval_data *results;
+ const char *comm;
if (!next_pid_field) {
next_pid_field = tep_find_field(event, "next_pid");
@@ -101,7 +102,8 @@ static int sched_callback(struct tracecmd_input *handle, struct tep_event *event
delta = record->ts - results[0].number_64;
traceeval_results_release(data->teval_wakeup, results);
- TRACEEVAL_SET_CSTRING(keys[0], record->data + next_comm_field->offset);
+ comm = (char *)record->data + next_comm_field->offset;
+ TRACEEVAL_SET_CSTRING(keys[0],comm);
TRACEEVAL_SET_NUMBER(keys[1], pid);
TRACEEVAL_SET_NUMBER_64(vals[0], record->ts);
--
2.40.1
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