perf dso: Add dso__has_symbols() method

To replace longer code sequences in various places.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-tlk3klbkfyjrbfjvryyznfju@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-report.c

@@ -525,7 +525,7 @@ static void report__warn_kptr_restrict(const struct report *rep)
 
 		if (kernel_map) {
 			const struct dso *kdso = kernel_map->dso;
-			if (!RB_EMPTY_ROOT(&kdso->symbols[MAP__FUNCTION])) {
+			if (dso__has_symbols(kdso, MAP__FUNCTION)) {
 				desc = "If some relocation was applied (e.g. "
 				       "kexec) symbols may be misresolved.";
 			}

tools/perf/builtin-top.c

@@ -742,7 +742,7 @@ static void perf_event__process_sample(struct perf_tool *tool,
 "Kernel address maps (/proc/{kallsyms,modules}) are restricted.\n\n"
 "Check /proc/sys/kernel/kptr_restrict.\n\n"
 "Kernel%s samples will not be resolved.\n",
-			  al.map && !RB_EMPTY_ROOT(&al.map->dso->symbols[MAP__FUNCTION]) ?
+			  al.map && dso__has_symbols(al.map->dso, MAP__FUNCTION) ?
 			  " modules" : "");
 			if (use_browser <= 0)
 				sleep(5);
@@ -765,7 +765,7 @@ static void perf_event__process_sample(struct perf_tool *tool,
 		 */
 		if (!machine->kptr_restrict_warned && !top->vmlinux_warned &&
 		    __map__is_kernel(al.map) &&
-		    RB_EMPTY_ROOT(&al.map->dso->symbols[MAP__FUNCTION])) {
+		    dso__has_symbols(al.map->dso, MAP__FUNCTION)) {
 			if (symbol_conf.vmlinux_name) {
 				char serr[256];
 				dso__strerror_load(al.map->dso, serr, sizeof(serr));

tools/perf/util/dso.h

@@ -233,6 +233,11 @@ static inline void __dso__zput(struct dso **dso)
 
 bool dso__loaded(const struct dso *dso, enum map_type type);
 
+static inline bool dso__has_symbols(const struct dso *dso, enum map_type type)
+{
+	return !RB_EMPTY_ROOT(&dso->symbols[type]);
+}
+
 bool dso__sorted_by_name(const struct dso *dso, enum map_type type);
 void dso__set_sorted_by_name(struct dso *dso, enum map_type type);
 void dso__sort_by_name(struct dso *dso, enum map_type type);