Re: [PATCH v2 05/10] perf trace: Add a new argument to trace__btf_scnprintf()

[Arnaldo Carvalho de Melo <acme@kernel.org>]

On Thu, Aug 22, 2024 at 03:00:30PM -0300, Arnaldo Carvalho de Melo wrote:
> On Thu, Aug 15, 2024 at 09:36:21AM +0800, Howard Chu wrote:
> > Pass the struct syscall_arg, so that we can use the augmented_arg later
> > in the struct augmentation.
> 
> Breaks the build with:
> 
> builtin-trace.c: In function ‘trace__btf_scnprintf’:
> builtin-trace.c:1011:78: error: unused parameter ‘arg’ [-Werror=unused-parameter]
>  1011 |                                    size_t size, int val, struct syscall_arg *arg, char *type)
>       |                                                          ~~~~~~~~~~~~~~~~~~~~^~~
>   LD      /tmp/build/perf-tools-next/util/perf-util-in.o
>   LD      /tmp/build/perf-tools-next/perf-util-in.o
>   AR      /tmp/build/perf-tools-next/libperf-util.a
>   GEN     /tmp/build/perf-tools-next/python/perf.cpython-312-x86_64-linux-gnu.so
> cc1: all warnings being treated as errors
> 
> So we either use __maybe_unused at this point or combine it with the
> patch where it really gets used. I think the later is better, will do.

So here what I think we should do is to use the patch below, ok? I'm
continuing...

- Arnaldo

---

From 2c1ea68ac3d18109d96bd16e2860e076d2e0d61e Mon Sep 17 00:00:00 2001
From: Arnaldo Carvalho de Melo <acme@redhat.com>
Date: Thu, 22 Aug 2024 15:10:27 -0300
Subject: [PATCH 1/1] perf trace: Pass the richer 'struct syscall_arg' pointer
 to trace__btf_scnprintf()

Since we'll need it later in the current patch series and we can get the
syscall_arg_fmt from syscall_arg->fmt.

Based-on-a-patch-by: Howard Chu <howardchu95@gmail.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/lkml/Zsd8vqCrTh5h69rp@x1
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-trace.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/tools/perf/builtin-trace.c b/tools/perf/builtin-trace.c
index 37ca96e130a5862d..a909880bd25e51d1 100644
--- a/tools/perf/builtin-trace.c
+++ b/tools/perf/builtin-trace.c
@@ -1007,9 +1007,11 @@ static size_t btf_enum_scnprintf(const struct btf_type *type, struct btf *btf, c
 	return 0;
 }
 
-static size_t trace__btf_scnprintf(struct trace *trace, struct syscall_arg_fmt *arg_fmt, char *bf,
+static size_t trace__btf_scnprintf(struct trace *trace, struct syscall_arg *arg, char *bf,
 				   size_t size, int val, char *type)
 {
+	struct syscall_arg_fmt *arg_fmt = arg->fmt;
+
 	if (trace->btf == NULL)
 		return 0;
 
@@ -1029,7 +1031,7 @@ static size_t trace__btf_scnprintf(struct trace *trace, struct syscall_arg_fmt *
 }
 
 #else // HAVE_LIBBPF_SUPPORT
-static size_t trace__btf_scnprintf(struct trace *trace __maybe_unused, struct syscall_arg_fmt *arg_fmt __maybe_unused,
+static size_t trace__btf_scnprintf(struct trace *trace __maybe_unused, struct syscall_arg *arg __maybe_unused,
 				   char *bf __maybe_unused, size_t size __maybe_unused, int val __maybe_unused,
 				   char *type __maybe_unused)
 {
@@ -2284,7 +2286,7 @@ static size_t syscall__scnprintf_args(struct syscall *sc, char *bf, size_t size,
 			if (trace->show_arg_names)
 				printed += scnprintf(bf + printed, size - printed, "%s: ", field->name);
 
-			btf_printed = trace__btf_scnprintf(trace, &sc->arg_fmt[arg.idx], bf + printed,
+			btf_printed = trace__btf_scnprintf(trace, &arg, bf + printed,
 							   size - printed, val, field->type);
 			if (btf_printed) {
 				printed += btf_printed;
@@ -2987,7 +2989,7 @@ static size_t trace__fprintf_tp_fields(struct trace *trace, struct evsel *evsel,
 		if (trace->show_arg_names)
 			printed += scnprintf(bf + printed, size - printed, "%s: ", field->name);
 
-		btf_printed = trace__btf_scnprintf(trace, arg, bf + printed, size - printed, val, field->type);
+		btf_printed = trace__btf_scnprintf(trace, &syscall_arg, bf + printed, size - printed, val, field->type);
 		if (btf_printed) {
 			printed += btf_printed;
 			continue;
-- 
2.46.0