perf session: Constify tool

Make tool const now that all uses are const and
perf_tool__fill_defaults() won't be used. The aim is to better capture
that sessions don't mutate tools.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ilkka Koskinen <ilkka@os.amperecomputing.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Jonathan Cameron <jonathan.cameron@huawei.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: Oliver Upton <oliver.upton@linux.dev>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <song@kernel.org>
Cc: Sun Haiyong <sunhaiyong@loongson.cn>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yanteng Si <siyanteng@loongson.cn>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: https://lore.kernel.org/r/20240812204720.631678-28-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/session.c

@@ -1770,7 +1770,7 @@ static int __perf_session__process_decomp_events(struct perf_session *session);
 static int __perf_session__process_pipe_events(struct perf_session *session)
 {
 	struct ordered_events *oe = &session->ordered_events;
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct ui_progress prog;
 	union perf_event *event;
 	uint32_t size, cur_size = 0;
@@ -2200,7 +2200,7 @@ static int __perf_session__process_events(struct perf_session *session)
 		.in_place_update = session->data->in_place_update,
 	};
 	struct ordered_events *oe = &session->ordered_events;
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	struct ui_progress prog;
 	int err;
 
@@ -2250,7 +2250,7 @@ static int __perf_session__process_events(struct perf_session *session)
 static int __perf_session__process_dir_events(struct perf_session *session)
 {
 	struct perf_data *data = session->data;
-	struct perf_tool *tool = session->tool;
+	const struct perf_tool *tool = session->tool;
 	int i, ret, readers, nr_readers;
 	struct ui_progress prog;
 	u64 total_size = perf_data__size(session->data);

tools/perf/util/session.h

@@ -43,7 +43,7 @@ struct perf_session {
 	u64			one_mmap_offset;
 	struct ordered_events	ordered_events;
 	struct perf_data	*data;
-	struct perf_tool	*tool;
+	const struct perf_tool	*tool;
 	u64			bytes_transferred;
 	u64			bytes_compressed;
 	struct zstd_data	zstd_data;