[LTP] [PATCH v2 1/2] tst_net.sh: Detect IPv6 disabled via sysct

[Petr Vorel <pvorel@suse.cz>]

net.ipv6.conf.all.disable_ipv6=1 disables IPv6 on all interfaces
(including both already created and later created).

The check prevent failures on IPv6 tests, and error messages on both
IPv4 and IPv4 tests:

    # sysctl -w net.ipv6.conf.all.disable_ipv6=1
    # ./ping02.sh -6
    ping02 1 TINFO: tst_rhost_run: cmd: [ -f /proc/net/if_inet6 ]
    ping02 1 TINFO: NETNS: sh -c " [ -f /proc/net/if_inet6 ] || echo RTERR" 2>&1
    ping02 1 TINFO: initialize 'lhost' 'ltp_ns_veth2' interface
    ping02 1 TINFO: add local addr 10.0.0.2/24
    ping02 1 TINFO: add local addr fd00:1:1:1::2/64
    RTNETLINK answers: Permission denied
    ping02 1 TINFO: initialize 'rhost' 'ltp_ns_veth1' interface
    ...
    ping02 1 TINFO: timeout per run is 0h 5m 0s
    ping6: connect: Network is unreachable
    ping02 1 TFAIL: ping6 -I ltp_ns_veth2 -c 3 -s 8 -f -p 000102030405060708090a0b0c0d0e0f fd00:1:1:1::1 >/dev/null failed unexpectedly

Suggested-by: Cyril Hrubis <chrubis@suse.cz>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
---
 testcases/lib/tst_net.sh | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/testcases/lib/tst_net.sh b/testcases/lib/tst_net.sh
index fc64a588ae..96eed50793 100644
--- a/testcases/lib/tst_net.sh
+++ b/testcases/lib/tst_net.sh
@@ -84,25 +84,41 @@ tst_brk_()
 	[ -z "$TST_USE_LEGACY_API" ] && tst_brk $@ || tst_brkm $@
 }
 
+# Detect IPv6 disabled via ipv6.disable=1 kernel cmdline parameter
+# or sysctl net.ipv6.conf.all.disable_ipv6=1 (disables IPv6 on all
+# interfaces (including both already created and later created).
+# $TST_NET_IPV6_ENABLED: 1 on IPv6 enabled, 0 on IPv6 disabled.
 tst_net_detect_ipv6()
 {
 	local type="${1:-lhost}"
 	local cmd='[ -f /proc/net/if_inet6 ]'
-	local ret
+	local disabled iface ret
 
 	if [ "$type" = "lhost" ]; then
 		$cmd
 	else
 		tst_rhost_run -c "$cmd"
 	fi
-	ret=$?
 
-	if [ $ret -eq 0 ]; then
-		TST_NET_IPV6_ENABLED=1
+	if [ $? -ne 0 ]; then
+		TST_NET_IPV6_ENABLED=0
+		tst_res_ TINFO "IPv6 disabled on $type via ipv6.disable=1"
+		return
+	fi
+
+	cmd='sysctl -n net.ipv6.conf.all.disable_ipv6'
+	if [ "$type" = "lhost" ]; then
+		disabled=$($cmd)
 	else
+		disabled=$(tst_rhost_run -c "$cmd")
+	fi
+	if [ $disabled = 1 ]; then
+		tst_res_ TINFO "IPv6 disabled on $type net.ipv6.conf.all.disable_ipv6=1"
 		TST_NET_IPV6_ENABLED=0
-		tst_res_ TINFO "IPv6 disabled on $type"
+		return
 	fi
+
+	TST_NET_IPV6_ENABLED=1
 }
 
 tst_net_require_ipv6()
-- 
2.39.1


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