[PATCH V3] tools/testing/selftests/sysctl: Add pre-check to the value of writes_strict

[Orson Zhai <orson.zhai@xxxxxxxxxx>]

Sysctl test will fail in some items if the value of /proc/sys/kernel
/sysctrl_writes_strict is 0 as the default value in kernel older than v4.5.

Make this test more robust and compatible with older kernels by checking and
update sysctrl_writes_strict value and restore it when test is done.

Signed-off-by: Orson Zhai <orson.zhai@xxxxxxxxxx>
Reviewed-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Tested-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
---
 tools/testing/selftests/sysctl/common_tests     | 22 ++++++++++++++++++++++
 tools/testing/selftests/sysctl/run_numerictests |  2 +-
 tools/testing/selftests/sysctl/run_stringtests  |  2 +-
 3 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/tools/testing/selftests/sysctl/common_tests
b/tools/testing/selftests/sysctl/common_tests
index 17d534b1b7b4..dfb1fcfc3142 100644
--- a/tools/testing/selftests/sysctl/common_tests
+++ b/tools/testing/selftests/sysctl/common_tests
@@ -24,6 +24,14 @@ verify()
        return 0
 }

+exit_test()
+{
+       if [ ! -z ${old_strict} ]; then
+               echo ${old_strict} > ${WRITES_STRICT}
+       fi
+       exit $rc
+}
+
 trap 'set_orig; rm -f "${TEST_FILE}"' EXIT

 rc=0
@@ -63,6 +71,20 @@ else
        echo "ok"
 fi

+echo -n "Checking write strict setting ... "
+WRITES_STRICT="${SYSCTL}/kernel/sysctl_writes_strict"
+if [ ! -e ${WRITES_STRICT} ]; then
+       echo "FAIL, but skip in case of old kernel" >&2
+else
+       old_strict=$(cat ${WRITES_STRICT})
+       if [ "$old_strict" = "1" ]; then
+               echo "ok"
+       else
+               echo "FAIL, strict value is 0 but force to 1 to continue" >&2
+               echo "1" > ${WRITES_STRICT}
+       fi
+fi
+
 # Now that we've validated the sanity of "set_test" and "set_orig",
 # we can use those functions to set starting states before running
 # specific behavioral tests.
diff --git a/tools/testing/selftests/sysctl/run_numerictests
b/tools/testing/selftests/sysctl/run_numerictests
index 8510f93f2d14..e6e76c93d948 100755
--- a/tools/testing/selftests/sysctl/run_numerictests
+++ b/tools/testing/selftests/sysctl/run_numerictests
@@ -7,4 +7,4 @@ TEST_STR=$(( $ORIG + 1 ))

 . ./common_tests

-exit $rc
+exit_test
diff --git a/tools/testing/selftests/sysctl/run_stringtests
b/tools/testing/selftests/sysctl/run_stringtests
index 90a9293d520c..857ec667fb02 100755
--- a/tools/testing/selftests/sysctl/run_stringtests
+++ b/tools/testing/selftests/sysctl/run_stringtests
@@ -74,4 +74,4 @@ else
        echo "ok"
 fi

-exit $rc
+exit_test
--
2.12.2
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