On Fri, Aug 22, 2025 at 3:28 PM Paolo Bonzini <pbonz...@redhat.com> wrote:
>
> This simplifies the Python code and reduces the size of the tracepoints.
>
> Signed-off-by: Paolo Bonzini <pbonz...@redhat.com>
> ---
Nice.
Reviewed-by: Manos Pitsidianakis <manos.pitsidiana...@linaro.org>
> tests/tracetool/ftrace.h | 28 ++++++----------------------
> trace/ftrace.h | 1 +
> trace/ftrace.c | 15 +++++++++++++++
> scripts/tracetool/backend/ftrace.py | 12 ++----------
> 4 files changed, 24 insertions(+), 32 deletions(-)
>
> diff --git a/tests/tracetool/ftrace.h b/tests/tracetool/ftrace.h
> index fe22ea0f09f..1dfe4239413 100644
> --- a/tests/tracetool/ftrace.h
> +++ b/tests/tracetool/ftrace.h
> @@ -21,18 +21,10 @@ extern uint16_t _TRACE_TEST_WIBBLE_DSTATE;
>
> static inline void trace_test_blah(void *context, const char *filename)
> {
> - {
> - char ftrace_buf[MAX_TRACE_STRLEN];
> - int unused __attribute__ ((unused));
> - int trlen;
> - if (trace_event_get_state(TRACE_TEST_BLAH)) {
> + if (trace_event_get_state(TRACE_TEST_BLAH)) {
> #line 4 "trace-events"
> - trlen = snprintf(ftrace_buf, MAX_TRACE_STRLEN,
> - "test_blah " "Blah context=%p filename=%s" "\n"
> , context, filename);
> -#line 33 "ftrace.h"
> - trlen = MIN(trlen, MAX_TRACE_STRLEN - 1);
> - unused = write(trace_marker_fd, ftrace_buf, trlen);
> - }
> + ftrace_write("test_blah " "Blah context=%p filename=%s" "\n" ,
> context, filename);
> +#line 28 "ftrace.h"
> }
> }
>
> @@ -42,18 +34,10 @@ static inline void trace_test_blah(void *context, const
> char *filename)
>
> static inline void trace_test_wibble(void *context, int value)
> {
> - {
> - char ftrace_buf[MAX_TRACE_STRLEN];
> - int unused __attribute__ ((unused));
> - int trlen;
> - if (trace_event_get_state(TRACE_TEST_WIBBLE)) {
> + if (trace_event_get_state(TRACE_TEST_WIBBLE)) {
> #line 5 "trace-events"
> - trlen = snprintf(ftrace_buf, MAX_TRACE_STRLEN,
> - "test_wibble " "Wibble context=%p value=%d"
> "\n" , context, value);
> -#line 54 "ftrace.h"
> - trlen = MIN(trlen, MAX_TRACE_STRLEN - 1);
> - unused = write(trace_marker_fd, ftrace_buf, trlen);
> - }
> + ftrace_write("test_wibble " "Wibble context=%p value=%d" "\n" ,
> context, value);
> +#line 41 "ftrace.h"
> }
> }
> #endif /* TRACE_TESTSUITE_GENERATED_TRACERS_H */
> diff --git a/trace/ftrace.h b/trace/ftrace.h
> index cb5e35d2171..16c122816d1 100644
> --- a/trace/ftrace.h
> +++ b/trace/ftrace.h
> @@ -8,5 +8,6 @@
> extern int trace_marker_fd;
>
> bool ftrace_init(void);
> +G_GNUC_PRINTF(1, 2) void ftrace_write(const char *fmt, ...);
>
> #endif /* TRACE_FTRACE_H */
> diff --git a/trace/ftrace.c b/trace/ftrace.c
> index 9749543d9b2..6875faedb9c 100644
> --- a/trace/ftrace.c
> +++ b/trace/ftrace.c
> @@ -38,6 +38,21 @@ static int find_mount(char *mount_point, const char
> *fstype)
> return ret;
> }
>
> +void ftrace_write(const char *fmt, ...)
> +{
> + char ftrace_buf[MAX_TRACE_STRLEN];
> + int unused __attribute__ ((unused));
> + int trlen;
> + va_list ap;
> +
> + va_start(ap, fmt);
> + trlen = vsnprintf(ftrace_buf, MAX_TRACE_STRLEN, fmt, ap);
> + va_end(ap);
> +
> + trlen = MIN(trlen, MAX_TRACE_STRLEN - 1);
> + unused = write(trace_marker_fd, ftrace_buf, trlen);
> +}
> +
> bool ftrace_init(void)
> {
> char mount_point[PATH_MAX];
> diff --git a/scripts/tracetool/backend/ftrace.py
> b/scripts/tracetool/backend/ftrace.py
> index 5fa30ccc08e..a07f8a9dfd8 100644
> --- a/scripts/tracetool/backend/ftrace.py
> +++ b/scripts/tracetool/backend/ftrace.py
> @@ -28,18 +28,10 @@ def generate_h(event, group):
> if len(event.args) > 0:
> argnames = ", " + argnames
>
> - out(' {',
> - ' char ftrace_buf[MAX_TRACE_STRLEN];',
> - ' int unused __attribute__ ((unused));',
> - ' int trlen;',
> - ' if (trace_event_get_state(%(event_id)s)) {',
> + out(' if (trace_event_get_state(%(event_id)s)) {',
> '#line %(event_lineno)d "%(event_filename)s"',
> - ' trlen = snprintf(ftrace_buf, MAX_TRACE_STRLEN,',
> - ' "%(name)s " %(fmt)s "\\n"
> %(argnames)s);',
> + ' ftrace_write("%(name)s " %(fmt)s "\\n" %(argnames)s);',
> '#line %(out_next_lineno)d "%(out_filename)s"',
> - ' trlen = MIN(trlen, MAX_TRACE_STRLEN - 1);',
> - ' unused = write(trace_marker_fd, ftrace_buf, trlen);',
> - ' }',
> ' }',
> name=event.name,
> args=event.args,
> --
> 2.50.1
>
>
