perf record: Ensure return non-zero rc when mmap fail

perf_evlist__mmap_ex() can fail without setting errno (for example, fail
in condition checking. In this case all syscall is success).

If this happen, record__open() incorrectly returns 0. Force setting rc
is a quick way to avoid this problem, or we have to follow all possible
code path in perf_evlist__mmap_ex() to make sure there's at least one
system call before returning an error.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: He Kuang <hekuang@huawei.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1456479154-136027-30-git-send-email-wangnan0@huawei.com
Signed-off-by: He Kuang <hekuang@huawei.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 4 insertions, 1 deletions

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 46e2772f838e..515510ecc76a 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -324,7 +324,10 @@ try_again:
                 } else {
                         pr_err("failed to mmap with %d (%s)\n", errno,
                                 strerror_r(errno, msg, sizeof(msg)));
-                        rc = -errno;
+                        if (errno)
+                                rc = -errno;
+                        else
+                                rc = -EINVAL;
                 }
                 goto out;
         }