perf dsos: Tidy reference counting and locking

Move more functionality into dsos.c generally from machine.c, renaming
functions to match their new usage.

The find function is made to always "get" before returning a dso.

Reduce the scope of locks in vdso to match the locking paradigm.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Anne Macedo <retpolanne@posteo.net>
Cc: Athira Rajeev <atrajeev@linux.vnet.ibm.com>
Cc: Ben Gainey <ben.gainey@arm.com>
Cc: Changbin Du <changbin.du@huawei.com>
Cc: Chengen Du <chengen.du@canonical.com>
Cc: Colin Ian King <colin.i.king@gmail.com>
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: K Prateek Nayak <kprateek.nayak@amd.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linux.dev>
Cc: Li Dong <lidong@vivo.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Markus Elfring <Markus.Elfring@web.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paran Lee <p4ranlee@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Song Liu <song@kernel.org>
Cc: Sun Haiyong <sunhaiyong@loongson.cn>
Cc: Thomas Richter <tmricht@linux.ibm.com>
Cc: Yang Jihong <yangjihong1@huawei.com>
Cc: Yanteng Si <siyanteng@loongson.cn>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: zhaimingbing <zhaimingbing@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20240410064214.2755936-3-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 20 insertions, 28 deletions

diff --git a/tools/perf/util/vdso.c b/tools/perf/util/vdso.c
index df8963796187..35532dcbff74 100644
--- a/tools/perf/util/vdso.c
+++ b/tools/perf/util/vdso.c
@@ -133,8 +133,6 @@ static struct dso *__machine__addnew_vdso(struct machine *machine, const char *s
 	if (dso != NULL) {
 		__dsos__add(&machine->dsos, dso);
 		dso__set_long_name(dso, long_name, false);
-		/* Put dso here because __dsos_add already got it */
-		dso__put(dso);
 	}
 
 	return dso;
@@ -252,17 +250,15 @@ static struct dso *__machine__findnew_compat(struct machine *machine,
 	const char *file_name;
 	struct dso *dso;
 
-	dso = __dsos__find(&machine->dsos, vdso_file->dso_name, true);
+	dso = dsos__find(&machine->dsos, vdso_file->dso_name, true);
 	if (dso)
-		goto out;
+		return dso;
 
 	file_name = vdso__get_compat_file(vdso_file);
 	if (!file_name)
-		goto out;
+		return NULL;
 
-	dso = __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
-out:
-	return dso;
+	return __machine__addnew_vdso(machine, vdso_file->dso_name, file_name);
 }
 
 static int __machine__findnew_vdso_compat(struct machine *machine,
@@ -308,21 +304,21 @@ static struct dso *machine__find_vdso(struct machine *machine,
 	dso_type = machine__thread_dso_type(machine, thread);
 	switch (dso_type) {
 	case DSO__TYPE_32BIT:
-		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
+		dso = dsos__find(&machine->dsos, DSO__NAME_VDSO32, true);
 		if (!dso) {
-			dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO,
-					   true);
+			dso = dsos__find(&machine->dsos, DSO__NAME_VDSO,
+					 true);
 			if (dso && dso_type != dso__type(dso, machine))
 				dso = NULL;
 		}
 		break;
 	case DSO__TYPE_X32BIT:
-		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
+		dso = dsos__find(&machine->dsos, DSO__NAME_VDSOX32, true);
 		break;
 	case DSO__TYPE_64BIT:
 	case DSO__TYPE_UNKNOWN:
 	default:
-		dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
+		dso = dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
 		break;
 	}
 
@@ -334,37 +330,33 @@ struct dso *machine__findnew_vdso(struct machine *machine,
 {
 	struct vdso_info *vdso_info;
 	struct dso *dso = NULL;
+	char *file;
 
-	down_write(&machine->dsos.lock);
 	if (!machine->vdso_info)
 		machine->vdso_info = vdso_info__new();
 
 	vdso_info = machine->vdso_info;
 	if (!vdso_info)
-		goto out_unlock;
+		return NULL;
 
 	dso = machine__find_vdso(machine, thread);
 	if (dso)
-		goto out_unlock;
+		return dso;
 
 #if BITS_PER_LONG == 64
 	if (__machine__findnew_vdso_compat(machine, thread, vdso_info, &dso))
-		goto out_unlock;
+		return dso;
 #endif
 
-	dso = __dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
-	if (!dso) {
-		char *file;
+	dso = dsos__find(&machine->dsos, DSO__NAME_VDSO, true);
+	if (dso)
+		return dso;
 
-		file = get_file(&vdso_info->vdso);
-		if (file)
-			dso = __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
-	}
+	file = get_file(&vdso_info->vdso);
+	if (!file)
+		return NULL;
 
-out_unlock:
-	dso__get(dso);
-	up_write(&machine->dsos.lock);
-	return dso;
+	return __machine__addnew_vdso(machine, DSO__NAME_VDSO, file);
 }
 
 bool dso__is_vdso(struct dso *dso)