perf probe: Do not use map_load filters for function

It is simpler to just do the loop, no need for globals and the last user
of such facility disappears.

Testing:

# perf probe -F [a-z]*recvmsg
aead_recvmsg
compat_SyS_recvmsg
compat_sys_recvmsg
hash_recvmsg
inet_recvmsg
kernel_recvmsg
netlink_recvmsg
packet_recvmsg
ping_recvmsg
raw_recvmsg
rawv6_recvmsg
rng_recvmsg
security_socket_recvmsg
selinux_socket_recvmsg
skcipher_recvmsg
sock_common_recvmsg
sock_no_recvmsg
sock_recvmsg
sys_recvmsg
tcp_recvmsg
udp_recvmsg
udpv6_recvmsg
unix_dgram_recvmsg
unix_seqpacket_recvmsg
unix_stream_recvmsg
#

Without filters:

# perf probe -F | tail -5
zswap_pool_create
zswap_pool_current
zswap_update_total_size
zswap_writeback_entry
zswap_zpool_param_set
#
# perf probe -F | wc -l
33311
#

Acked-by: Masami Hiramatsu <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Wang Nan <[e-mail]>
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/probe-event.c

···
 	return ret;
 }
 
-/* TODO: don't use a global variable for filter ... */
-static struct strfilter *available_func_filter;
-
-/*
- * If a symbol corresponds to a function with global binding and
- * matches filter return 0. For all others return 1.
- */
-static int filter_available_functions(struct map *map __maybe_unused,
-				      struct symbol *sym)
-{
-	if (strfilter__compare(available_func_filter, sym->name))
-		return 0;
-	return 1;
-}
-
 int show_available_funcs(const char *target, struct strfilter *_filter,
 					bool user)
 {
+        struct rb_node *nd;
 	struct map *map;
 	int ret;
 
···
 		return -EINVAL;
 	}
 
-	/* Load symbols with given filter */
-	available_func_filter = _filter;
-	ret = map__load(map, filter_available_functions);
+	ret = map__load(map, NULL);
 	if (ret) {
 		if (ret == -2) {
 			char *str = strfilter__string(_filter);
···
 
 	/* Show all (filtered) symbols */
 	setup_pager();
-	dso__fprintf_symbols_by_name(map->dso, map->type, stdout);
+
+        for (nd = rb_first(&map->dso->symbol_names[map->type]); nd; nd = rb_next(nd)) {
+		struct symbol_name_rb_node *pos = rb_entry(nd, struct symbol_name_rb_node, rb_node);
+
+		if (strfilter__compare(_filter, pos->sym.name))
+			printf("%s\n", pos->sym.name);
+        }
+
 end:
 	if (user) {
 		map__put(map);