[tip:perf/core] perf test bpf: Improve message about expected samples

[tip-bot for Arnaldo Carvalho de Melo]

Commit-ID:  6703c9771d83ebe092b0d49cb0609a3f9d8b4ff7
Gitweb:     https://git.kernel.org/tip/6703c9771d83ebe092b0d49cb0609a3f9d8b4ff7
Author:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
AuthorDate: Tue, 2 Jan 2018 14:59:21 -0300
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 8 Jan 2018 11:11:56 -0300

perf test bpf: Improve message about expected samples

When failing on one of the BPF tests we were just stating:

  BPF filter result incorrect

Add some more info to help figuring out the problem:

 BPF filter result incorrect, expected 56, got 0 samples

This came out while investigating this failure, first seen after
updating the kernel to the 4.15.0-rc6 tag:

  [root@jouet ~]# perf test bpf
  39: BPF filter               :
  39.1: Basic BPF filtering    : FAILED!
  39.2: BPF pinning            : Skip
  39.3: BPF prologue generation: Skip
  39.4: BPF relocation checker : Skip
  [root@jouet ~]#

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Wang Nan <wangnan0@xxxxxxxxxx>
Link: https://lkml.kernel.org/n/tip-403npu7daupv6b2bmxliv5pk@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/tests/bpf.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/bpf.c b/tools/perf/tests/bpf.c
index c433dd3..057c6b8 100644
--- a/tools/perf/tests/bpf.c
+++ b/tools/perf/tests/bpf.c
@@ -190,7 +190,7 @@ static int do_test(struct bpf_object *obj, int (*func)(void),
 	}
 
 	if (count != expect) {
-		pr_debug("BPF filter result incorrect\n");
+		pr_debug("BPF filter result incorrect, expected %d, got %d samples\n", expect, count);
 		goto out_delete_evlist;
 	}