selftests: net: return Kselftest Skip code for skipped tests

When net test is skipped because of unmet dependencies and/or unsupported
configuration, it returns 0 which is treated as a pass by the Kselftest
framework. This leads to false positive result even when the test could
not be run.

Change it to return kselftest skip code when a test gets skipped to
clearly report that the test could not be run.

Kselftest framework SKIP code is 4 and the framework prints appropriate
messages to indicate that the test is skipped.

Change psock_tpacket to use ksft_exit_skip() when a non-root user runs
the test and add an explicit check for root and a clear message, instead
of failing the test when /sys/power/state file open fails.

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>

tools/testing/selftests/net/psock_tpacket.c

@@ -60,6 +60,8 @@
 
 #include "psock_lib.h"
 
+#include "../kselftest.h"
+
 #ifndef bug_on
 # define bug_on(cond)		assert(!(cond))
 #endif
@@ -825,7 +827,7 @@ static int test_tpacket(int version, int type)
 		fprintf(stderr, "test: skip %s %s since user and kernel "
 			"space have different bit width\n",
 			tpacket_str[version], type_str[type]);
-		return 0;
+		return KSFT_SKIP;
 	}
 
 	sock = pfsocket(version);