Makes membarrier_test compatible with older kernels (LTS) by checking if
the membarrier features exist before running the tests.

Link: https://bugs.linaro.org/show_bug.cgi?id=3771
Signed-off-by: Rafael David Tinoco <rafael.tin...@linaro.org>
Cc: <sta...@vger.kernel.org> #v4.17
---
 .../selftests/membarrier/membarrier_test.c    | 69 +++++++++++--------
 1 file changed, 41 insertions(+), 28 deletions(-)

diff --git a/tools/testing/selftests/membarrier/membarrier_test.c 
b/tools/testing/selftests/membarrier/membarrier_test.c
index 6793f8ecc8e7..b96caa096e2f 100644
--- a/tools/testing/selftests/membarrier/membarrier_test.c
+++ b/tools/testing/selftests/membarrier/membarrier_test.c
@@ -225,7 +225,14 @@ static int test_membarrier_global_expedited_success(void)
 
 static int test_membarrier(void)
 {
-       int status;
+       int supported, status;
+
+       supported = sys_membarrier(MEMBARRIER_CMD_QUERY, 0);
+       if (supported < 0) {
+               ksft_test_result_fail(
+                       "sys_membarrier() failed to query supported cmds\n");
+               return supported;
+       }
 
        status = test_membarrier_cmd_fail();
        if (status)
@@ -236,21 +243,22 @@ static int test_membarrier(void)
        status = test_membarrier_global_success();
        if (status)
                return status;
-       status = test_membarrier_private_expedited_fail();
-       if (status)
-               return status;
-       status = test_membarrier_register_private_expedited_success();
-       if (status)
-               return status;
-       status = test_membarrier_private_expedited_success();
-       if (status)
-               return status;
-       status = sys_membarrier(MEMBARRIER_CMD_QUERY, 0);
-       if (status < 0) {
-               ksft_test_result_fail("sys_membarrier() failed\n");
-               return status;
+
+       /* commit 22e4ebb975822833b083533035233d128b30e98f added this feature */
+       if (supported & MEMBARRIER_CMD_PRIVATE_EXPEDITED) {
+               status = test_membarrier_private_expedited_fail();
+               if (status)
+                       return status;
+               status = test_membarrier_register_private_expedited_success();
+               if (status)
+                       return status;
+               status = test_membarrier_private_expedited_success();
+               if (status)
+                       return status;
        }
-       if (status & MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE) {
+
+       /* commit 70216e18e519a54a2f13569e8caff99a092a92d6 added this feature */
+       if (supported & MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE) {
                status = test_membarrier_private_expedited_sync_core_fail();
                if (status)
                        return status;
@@ -261,19 +269,24 @@ static int test_membarrier(void)
                if (status)
                        return status;
        }
-       /*
-        * It is valid to send a global membarrier from a non-registered
-        * process.
-        */
-       status = test_membarrier_global_expedited_success();
-       if (status)
-               return status;
-       status = test_membarrier_register_global_expedited_success();
-       if (status)
-               return status;
-       status = test_membarrier_global_expedited_success();
-       if (status)
-               return status;
+
+       /* commit c5f58bd58f432be5d92df33c5458e0bcbee3aadf added this feature */
+       if (supported & MEMBARRIER_CMD_GLOBAL_EXPEDITED) {
+               /*
+                * It is valid to send a global membarrier from a non-registered
+                * process.
+                */
+               status = test_membarrier_global_expedited_success();
+               if (status)
+                       return status;
+               status = test_membarrier_register_global_expedited_success();
+               if (status)
+                       return status;
+               status = test_membarrier_global_expedited_success();
+               if (status)
+                       return status;
+       }
+
        return 0;
 }
 
-- 
2.18.0

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