[PATCH] perf test: fix test case probe libc's inet_pton on s390x

[Thomas Richter <tmricht@linux.vnet.ibm.com>]

Perf test case probe libc's inet_pton & backtrace it with ping
fails on s390x. The reason is the 'realpath /lib64/ld*.so.* | uniq'
line which returns 2 libraries:

        root@s35lp76 shell]# realpath /lib64/ld*.so.* | uniq
        /usr/lib64/ld-2.26.so
        /usr/lib64/ld_pre_smc.so.1.0.1
        [root@s35lp76 shell]

This output makes the perf probe command lines invalid.

Use tool ldd to find out the libraries required by the bash and
check if symbol inet_pton is part of the libc library.
Some distros do not have a /lib64 directory.

I have also added a check for the existence of an IPv6
network interface before it is being used.

Signed-off-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Suggested-by: Hendrik Brückner <brueckner@linux.vnet.ibm.com>
Reviewed-by: Hendrik Brückner <brueckner@linux.vnet.ibm.com>
---
 tools/perf/tests/shell/trace+probe_libc_inet_pton.sh | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/perf/tests/shell/trace+probe_libc_inet_pton.sh b/tools/perf/tests/shell/trace+probe_libc_inet_pton.sh
index 7a84d73324e3..b9c913f1a360 100755
--- a/tools/perf/tests/shell/trace+probe_libc_inet_pton.sh
+++ b/tools/perf/tests/shell/trace+probe_libc_inet_pton.sh
@@ -10,8 +10,8 @@
 
 . $(dirname $0)/lib/probe.sh
 
-ld=$(realpath /lib64/ld*.so.* | uniq)
-libc=$(echo $ld | sed 's/ld/libc/g')
+libc=$(ldd $(which bash) 2>/dev/null | fgrep libc | awk '{ print $3 }')
+nm -g $libc 2>/dev/null | fgrep -q inet_pton || exit 254
 
 trace_libc_inet_pton_backtrace() {
 	idx=0
@@ -37,6 +37,9 @@ trace_libc_inet_pton_backtrace() {
 	done
 }
 
+# Check for IPv6 interface existence
+ip a sh lo | fgrep -q inet6 || exit 2
+
 skip_if_no_perf_probe && \
 perf probe -q $libc inet_pton && \
 trace_libc_inet_pton_backtrace
-- 
2.13.4