perf dso: Add dso__filename_with_chroot() to reduce number of accesses to dso->nsinfo members

We'll need to reference count dso->nsinfo, so reduce the number of
direct accesses by having a shorter form of obtaining a filename with
a chroot (namespace one).

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexey Bayduraev <alexey.v.bayduraev@linux.intel.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Riccardo Mancini <rickyman7@gmail.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Stephen Brennan <stephen.s.brennan@oracle.com>
Link: https://lore.kernel.org/lkml/ZD26ZlqSbgSyH5lX@kernel.org
[ Used nsinfo__pid(dso->nsinfo), as it was already present ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-inject.c

@@ -630,10 +630,8 @@ static int dso__read_build_id(struct dso *dso)
 	if (filename__read_build_id(dso->long_name, &dso->bid) > 0)
 		dso->has_build_id = true;
 	else if (dso->nsinfo) {
-		char *new_name;
+		char *new_name = dso__filename_with_chroot(dso, dso->long_name);
 
-		new_name = filename_with_chroot(dso->nsinfo->pid,
-						dso->long_name);
 		if (new_name && filename__read_build_id(new_name, &dso->bid) > 0)
 			dso->has_build_id = true;
 		free(new_name);

tools/perf/util/annotate.c

@@ -1692,8 +1692,7 @@ fallback:
 
 		mutex_lock(&dso->lock);
 		if (access(filename, R_OK) && errno == ENOENT && dso->nsinfo) {
-			char *new_name = filename_with_chroot(dso->nsinfo->pid,
-							      filename);
+			char *new_name = dso__filename_with_chroot(dso, filename);
 			if (new_name) {
 				strlcpy(filename, new_name, filename_size);
 				free(new_name);

tools/perf/util/dso.c

@@ -491,6 +491,11 @@ static int do_open(char *name)
 	return -1;
 }
 
+char *dso__filename_with_chroot(const struct dso *dso, const char *filename)
+{
+	return filename_with_chroot(nsinfo__pid(dso->nsinfo), filename);
+}
+
 static int __open_dso(struct dso *dso, struct machine *machine)
 {
 	int fd = -EINVAL;
@@ -515,7 +520,7 @@ static int __open_dso(struct dso *dso, struct machine *machine)
 		if (errno != ENOENT || dso->nsinfo == NULL)
 			goto out;
 
-		new_name = filename_with_chroot(dso->nsinfo->pid, name);
+		new_name = dso__filename_with_chroot(dso, name);
 		if (!new_name)
 			goto out;
 

tools/perf/util/dso.h

@@ -266,6 +266,8 @@ static inline bool dso__has_symbols(const struct dso *dso)
 	return !RB_EMPTY_ROOT(&dso->symbols.rb_root);
 }
 
+char *dso__filename_with_chroot(const struct dso *dso, const char *filename);
+
 bool dso__sorted_by_name(const struct dso *dso);
 void dso__set_sorted_by_name(struct dso *dso);
 void dso__sort_by_name(struct dso *dso);

tools/perf/util/dsos.c

@@ -91,8 +91,7 @@ bool __dsos__read_build_ids(struct list_head *head, bool with_hits)
 			have_build_id	  = true;
 			pos->has_build_id = true;
 		} else if (errno == ENOENT && pos->nsinfo) {
-			char *new_name = filename_with_chroot(pos->nsinfo->pid,
-							      pos->long_name);
+			char *new_name = dso__filename_with_chroot(pos, pos->long_name);
 
 			if (new_name && filename__read_build_id(new_name,
 								&pos->bid) > 0) {

tools/perf/util/symbol.c

@@ -1963,8 +1963,7 @@ int dso__load(struct dso *dso, struct map *map)
 
 		is_reg = is_regular_file(name);
 		if (!is_reg && errno == ENOENT && dso->nsinfo) {
-			char *new_name = filename_with_chroot(dso->nsinfo->pid,
-							      name);
+			char *new_name = dso__filename_with_chroot(dso, name);
 			if (new_name) {
 				is_reg = is_regular_file(new_name);
 				strlcpy(name, new_name, PATH_MAX);