Revert "selftests/harness: remove use of LINE_MAX"

Patch series "Selftests: Fix compilation warnings due to missing
_GNU_SOURCE definition", v2.

Since kselftest_harness.h introduces asprintf()[1], many selftests have
compilation warnings or errors due to missing _GNU_SOURCE definitions.

The issue stems from a lack of a LINE_MAX definition in Android (see
commit 38c957f), which is the reason why asprintf() was introduced. 
We tried adding _GNU_SOURCE definitions to more selftests to fix, but
asprintf() may continue to cause problems, and since it is quite late in
the 6.9 cycle, we would like to revert 8092162 first to provide
testing for forks[2].

[1] https://lore.kernel.org/all/[email protected]
[2] https://lore.kernel.org/linux-kselftest/[email protected]


This patch (of 2):

This reverts commit 8092162.

asprintf() is declared in stdio.h when defining _GNU_SOURCE, but stdio.h
is so common that many files don't define _GNU_SOURCE before including
stdio.h, and defining _GNU_SOURCE after including stdio.h will no longer
take effect, which causes warnings or even errors during compilation in
many selftests.

Revert 'commit 8092162 ("selftests/harness: remove use of LINE_MAX")'
as that came in quite late in the 6.9 cycle.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lore.kernel.org/linux-kselftest/[email protected]/
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 8092162 ("selftests/harness: remove use of LINE_MAX")
Signed-off-by: Tao Su <[email protected]>
Reviewed-by: Simon Horman <[email protected]>
Cc: Alexandre Belloni <[email protected]>
Cc: Bongsu Jeon <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David S. Miller <[email protected]>
Cc: Edward Liaw <[email protected]>
Cc: Eric Dumazet <[email protected]>
Cc: Ivan Orlov <[email protected]>
Cc: Jakub Kicinski <[email protected]>
Cc: Jarkko Sakkinen <[email protected]>
Cc: Jaroslav Kysela <[email protected]>
Cc: Mark Brown <[email protected]>
Cc: Paolo Abeni <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Sean Christopherson <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: Takashi Iwai <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: taosu-linux

tools/testing/selftests/kselftest_harness.h

@@ -56,6 +56,7 @@ static_assert(0, "kselftest harness requires _GNU_SOURCE to be defined");
 #include <asm/types.h>
 #include <ctype.h>
 #include <errno.h>
+#include <limits.h>
 #include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
@@ -1216,7 +1217,7 @@ void __run_test(struct __fixture_metadata *f,
 		struct __test_metadata *t)
 {
 	struct __test_xfail *xfail;
-	char *test_name;
+	char test_name[LINE_MAX];
 	const char *diagnostic;
 
 	/* reset test struct */
@@ -1227,12 +1228,8 @@ void __run_test(struct __fixture_metadata *f,
 	memset(t->env, 0, sizeof(t->env));
 	memset(t->results->reason, 0, sizeof(t->results->reason));
 
-	if (asprintf(&test_name, "%s%s%s.%s", f->name,
-		variant->name[0] ? "." : "", variant->name, t->name) == -1) {
-		ksft_print_msg("ERROR ALLOCATING MEMORY\n");
-		t->exit_code = KSFT_FAIL;
-		_exit(t->exit_code);
-	}
+	snprintf(test_name, sizeof(test_name), "%s%s%s.%s",
+		 f->name, variant->name[0] ? "." : "", variant->name, t->name);
 
 	ksft_print_msg(" RUN           %s ...\n", test_name);
 
@@ -1270,7 +1267,6 @@ void __run_test(struct __fixture_metadata *f,
 
 	ksft_test_result_code(t->exit_code, test_name,
 			      diagnostic ? "%s" : NULL, diagnostic);
-	free(test_name);
 }
 
 static int test_harness_run(int argc, char **argv)

tools/testing/selftests/mm/mdwe_test.c

@@ -7,7 +7,6 @@
 #include <linux/mman.h>
 #include <linux/prctl.h>
 
-#define _GNU_SOURCE
 #include <stdio.h>
 #include <stdlib.h>
 #include <sys/auxv.h>