zdtm: test MEMBARRIER_CMD_GLOBAL_EXPEDITED migration

Check membarrier registration both ways:
1. By issuing membarrier commands and checking if they succeed.
2. By issuing MEMBARRIER_CMD_GET_REGISTRATIONS.

The first way is needed for older kernels. The second way is needed to test
MEMBARRIER_CMD_GLOBAL_EXPEDITED.

test/zdtm/static/membarrier.c

@@ -8,14 +8,16 @@ const char *test_author = "Michał Mirosław <[email protected]>";
 
 /*
  * Define membarrier() CMDs to avoid depending on exact kernel header version.
- * FIXME: use MEMBARRIER_CMD_GET_REGISTRATIONS if supported by kernel.
  */
+#define MEMBARRIER_CMD_GLOBAL_EXPEDITED			    (1 << 1)
+#define MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED	    (1 << 2)
 #define MEMBARRIER_CMD_PRIVATE_EXPEDITED		    (1 << 3)
 #define MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED	    (1 << 4)
 #define MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE	    (1 << 5)
 #define MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE (1 << 6)
 #define MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ		    (1 << 7)
 #define MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ	    (1 << 8)
+#define MEMBARRIER_CMD_GET_REGISTRATIONS		    (1 << 9)
 
 static int membarrier(int cmd, unsigned int flags, int cpu_id)
 {
@@ -27,9 +29,14 @@ static const struct {
 	int register_cmd;
 	int execute_cmd;
 } membarrier_cmds[] = {
-	{ "",           MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED,           MEMBARRIER_CMD_PRIVATE_EXPEDITED },
-	{ "_SYNC_CORE", MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE, MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE },
-	{ "_RSEQ",      MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ,      MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ },
+	{ "GLOBAL_EXPEDITED",            MEMBARRIER_CMD_REGISTER_GLOBAL_EXPEDITED,
+		MEMBARRIER_CMD_GLOBAL_EXPEDITED },
+	{ "PRIVATE_EXPEDITED",           MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED,
+		MEMBARRIER_CMD_PRIVATE_EXPEDITED },
+	{ "PRIVATE_EXPEDITED_SYNC_CORE", MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_SYNC_CORE,
+		MEMBARRIER_CMD_PRIVATE_EXPEDITED_SYNC_CORE },
+	{ "PRIVATE_EXPEDITED_RSEQ",      MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED_RSEQ,
+		MEMBARRIER_CMD_PRIVATE_EXPEDITED_RSEQ },
 };
 static const int n_membarrier_cmds = sizeof(membarrier_cmds) / sizeof(*membarrier_cmds);
 
@@ -49,10 +56,10 @@ static int register_membarriers(void)
 		if (~barriers_supported & membarrier_cmds[i].register_cmd)
 			continue;
 
-		barriers_registered |= membarrier_cmds[i].execute_cmd;
+		barriers_registered |= membarrier_cmds[i].register_cmd;
 
 		if (membarrier(membarrier_cmds[i].register_cmd, 0, 0) < 0) {
-			pr_perror("membarrier(REGISTER_PRIVATE_EXPEDITED%s)", membarrier_cmds[i].name_suffix);
+			pr_perror("membarrier(REGISTER_%s)", membarrier_cmds[i].name_suffix);
 			all_ok = false;
 		}
 	}
@@ -71,15 +78,15 @@ static int register_membarriers(void)
 	return barriers_registered;
 }
 
-static bool check_membarriers(int barriers_registered)
+static bool check_membarriers_compat(int barriers_registered)
 {
 	bool all_ok = true;
 
 	for (int i = 0; i < n_membarrier_cmds; ++i) {
-		if (~barriers_registered & membarrier_cmds[i].execute_cmd)
+		if (~barriers_registered & membarrier_cmds[i].register_cmd)
 			continue;
 		if (membarrier(membarrier_cmds[i].execute_cmd, 0, 0) < 0) {
-			pr_perror("membarrier(PRIVATE_EXPEDITED%s)", membarrier_cmds[i].name_suffix);
+			pr_perror("membarrier(%s)", membarrier_cmds[i].name_suffix);
 			all_ok = false;
 		}
 	}
@@ -90,6 +97,32 @@ static bool check_membarriers(int barriers_registered)
 	return all_ok;
 }
 
+static bool check_membarriers_get_registrations(int barriers_registered)
+{
+	int ret = membarrier(MEMBARRIER_CMD_GET_REGISTRATIONS, 0, 0);
+	if (ret < 0) {
+		if (errno == EINVAL) {
+			test_msg("membarrier(MEMBARRIER_CMD_GET_REGISTRATIONS) not supported by running kernel");
+			return true;
+		}
+		fail("membarrier(MEMBARRIER_CMD_GET_REGISTRATIONS)");
+		return false;
+	}
+	if (ret != barriers_registered) {
+		fail("MEMBARRIER_CMD_GET_REGISTRATIONS check failed, expected: %d, got: %d",
+		     barriers_registered, ret);
+		return false;
+	}
+
+	return true;
+}
+
+static bool check_membarriers(int barriers_registered)
+{
+	return check_membarriers_compat(barriers_registered) &&
+	       check_membarriers_get_registrations(barriers_registered);
+}
+
 int main(int argc, char **argv)
 {
 	int barriers_registered;