[PATCH] [BUGFIX] perf-probe: Warn unmatched function filter correctly

From: Masami Hiramatsu
Date: Mon Jul 18 2016 - 12:13:03 EST


Warn unmatched function filter correctly instead of warning
"symbol-loading error", since that can be a filter issue.

>From the technical point of view, this adds a filter chech
in map__load and if there is a filter, it returns -2 (filter-out),
instead of -1 (error), and perf-probe checks it and change
message.

E.g. without this fix:
----
# perf probe -F rt_sp*
no symbols found in [kernel.kallsyms], maybe install a debug package?
Failed to load symbols in kernel
----
With this fix:
----
# perf probe -F rt_sp*
no symbols passed the given filter.
Failed to find symbols matched to "rt_sp*"
Error: Failed to show functions.
----

Reported-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
tools/perf/util/map.c | 3 +++
tools/perf/util/probe-event.c | 12 ++++++++++--
2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/map.c b/tools/perf/util/map.c
index b39b12a..728129a 100644
--- a/tools/perf/util/map.c
+++ b/tools/perf/util/map.c
@@ -312,6 +312,9 @@ int map__load(struct map *map, symbol_filter_t filter)
pr_warning("%.*s was updated (is prelink enabled?). "
"Restart the long running apps that use it!\n",
(int)real_len, name);
+ } else if (filter) {
+ pr_warning("no symbols passed the given filter.\n");
+ return -2; /* Empty but maybe by the filter */
} else {
pr_warning("no symbols found in %s, maybe install "
"a debug package?\n", name);
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index d4f8835..953dc1a 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -3312,8 +3312,16 @@ int show_available_funcs(const char *target, struct strfilter *_filter,

/* Load symbols with given filter */
available_func_filter = _filter;
- if (map__load(map, filter_available_functions)) {
- pr_err("Failed to load symbols in %s\n", (target) ? : "kernel");
+ ret = map__load(map, filter_available_functions);
+ if (ret) {
+ if (ret == -2) {
+ char *str = strfilter__string(_filter);
+ pr_err("Failed to find symbols matched to \"%s\"\n",
+ str);
+ free(str);
+ } else
+ pr_err("Failed to load symbols in %s\n",
+ (target) ? : "kernel");
goto end;
}
if (!dso__sorted_by_name(map->dso, map->type))