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Subject[PATCH 02/12] perf bpf: Mute libbpf when '-v' not set
Date
From: Wang Nan <wangnan0@huawei.com>

According to [1], libbpf should be muted. This patch reset info and
warning message level to ensure libbpf doesn't output anything even
if error happened.

[1] http://lkml.kernel.org/r/20151020151255.GF5119@kernel.org

Committer note:

Before:

Testing it with an incompatible kernel version in the .c file that
generated foo.o:

[root@zoo ~]# perf record -e /tmp/foo.o sleep 1
libbpf: load bpf program failed: Invalid argument
libbpf: -- BEGIN DUMP LOG ---
libbpf:

libbpf: -- END LOG --
libbpf: failed to load program 'fork=_do_fork'
libbpf: failed to load object '/tmp/foo.o'
event syntax error: '/tmp/foo.o'
\___ Invalid argument: Are you root and runing a CONFIG_BPF_SYSCALL kernel?

(add -v to see detail)
Run 'perf list' for a list of valid events

Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]

-e, --event <event> event selector. use 'perf list' to list available events
[root@zoo ~]#

After:

[root@zoo ~]# perf record -e /tmp/foo.o sleep 1
event syntax error: '/tmp/foo.o'
\___ Invalid argument: Are you root and runing a CONFIG_BPF_SYSCALL kernel?

(add -v to see detail)
Run 'perf list' for a list of valid events

Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]

-e, --event <event> event selector. use 'perf list' to list available events
[root@zoo ~]#

This, BTW, need fixing to emit a proper message by validating the
version in the foo.o "version" ELF section against the running kernel,
warning the user instead of asking the kernel to load a binary that it
will refuse due to unmatching kernel version.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1446547486-229499-3-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/bpf-loader.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index ba6f7526b282..0c5d174245bb 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -26,8 +26,8 @@ static int libbpf_##name(const char *fmt, ...) \
return ret; \
}

-DEFINE_PRINT_FN(warning, 0)
-DEFINE_PRINT_FN(info, 0)
+DEFINE_PRINT_FN(warning, 1)
+DEFINE_PRINT_FN(info, 1)
DEFINE_PRINT_FN(debug, 1)

struct bpf_prog_priv {
--
2.1.0


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