perf symbols: Set the DSO long name when using symbol_conf.vmlinux_name

We need to set the long name to the name specified via, for instance,
'perf annotate --vmlinux /path/to/vmlinux', if not it will remain as
'[kernel.kallsyms]' and that will make annotate fail when passing this
as the vmlinux name in the call to objdump.

The way this is setup grew unwieldly and dso__load_vmlinux is the
function that should allocate space for the long name, with callers not
assuming that filenames should be allocated somehow by then (strdup,
dso__build_id_filename, etc).

For now this is the minimalistic patch, a proper fix for .36 will be
made.

Reported-by: Stephane Eranian <eranian@google.com>
Tested-by: Stephane Eranian <eranian@google.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20100604003900.GD10469@ghostprotocols.net>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/util/symbol.c

@@ -1745,7 +1745,12 @@ static int dso__load_kernel_sym(struct dso *self, struct map *map,
 	if (symbol_conf.vmlinux_name != NULL) {
 		err = dso__load_vmlinux(self, map,
 					symbol_conf.vmlinux_name, filter);
-		goto out_try_fixup;
+		if (err > 0) {
+			dso__set_long_name(self,
+					   strdup(symbol_conf.vmlinux_name));
+			goto out_fixup;
+		}
+		return err;
 	}
 
 	if (vmlinux_path != NULL) {
@@ -1806,7 +1811,6 @@ do_kallsyms:
 		pr_debug("Using %s for symbols\n", kallsyms_filename);
 	free(kallsyms_allocated_filename);
 
-out_try_fixup:
 	if (err > 0) {
 out_fixup:
 		if (kallsyms_filename != NULL)