linux-kernel - [PATCH 1/2] selftest/futex: Make the error check more precise for futex_numa

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Message-ID: <20250901203327.53887-1-andrealmeid@igalia.com>
Date: Mon,  1 Sep 2025 17:33:26 -0300
From: André Almeida <andrealmeid@...lia.com>
To: Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
	linux-kernel@...r.kernel.org
Cc: Darren Hart <dvhart@...radead.org>,
	Davidlohr Bueso <dave@...olabs.net>,
	Ingo Molnar <mingo@...hat.com>,
	Juri Lelli <juri.lelli@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Valentin Schneider <vschneid@...hat.com>,
	Borislav Petkov <bp@...en8.de>,
	Waiman Long <longman@...hat.com>,
	kernel-dev@...lia.com,
	André Almeida <andrealmeid@...lia.com>
Subject: [PATCH 1/2] selftest/futex: Make the error check more precise for futex_numa_mpol

Instead of just checking if the syscall failed as expected, check as
well what is the error code returned, to check if it's match the
expectation and it's failing in the correct error path inside the
kernel.

Signed-off-by: André Almeida <andrealmeid@...lia.com>
---
This patch is aimed for 6.18
---
 .../futex/functional/futex_numa_mpol.c        | 36 +++++++++++--------
 1 file changed, 21 insertions(+), 15 deletions(-)

diff --git a/tools/testing/selftests/futex/functional/futex_numa_mpol.c b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
index 802c15c82190..c84441751235 100644
--- a/tools/testing/selftests/futex/functional/futex_numa_mpol.c
+++ b/tools/testing/selftests/futex/functional/futex_numa_mpol.c
@@ -77,7 +77,7 @@ static void join_max_threads(void)
 	}
 }
 
-static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flags)
+static void __test_futex(void *futex_ptr, int err_value, unsigned int futex_flags)
 {
 	int to_wake, ret, i, need_exit = 0;
 
@@ -88,11 +88,17 @@ static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flag
 
 	do {
 		ret = futex2_wake(futex_ptr, to_wake, futex_flags);
-		if (must_fail) {
-			if (ret < 0)
-				break;
-			ksft_exit_fail_msg("futex2_wake(%d, 0x%x) should fail, but didn't\n",
-					   to_wake, futex_flags);
+
+		if (err_value) {
+			if (ret >= 0)
+				ksft_exit_fail_msg("futex2_wake(%d, 0x%x) should fail, but didn't\n",
+						   to_wake, futex_flags);
+
+			if (errno != err_value)
+				ksft_exit_fail_msg("futex2_wake(%d, 0x%x) expected error was %d, but returned %d (%s)\n",
+						   to_wake, futex_flags, err_value, errno, strerror(errno));
+
+			break;
 		}
 		if (ret < 0) {
 			ksft_exit_fail_msg("Failed futex2_wake(%d, 0x%x): %m\n",
@@ -106,12 +112,12 @@ static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flag
 	join_max_threads();
 
 	for (i = 0; i < MAX_THREADS; i++) {
-		if (must_fail && thread_args[i].result != -1) {
+		if (err_value && thread_args[i].result != -1) {
 			ksft_print_msg("Thread %d should fail but succeeded (%d)\n",
 				       i, thread_args[i].result);
 			need_exit = 1;
 		}
-		if (!must_fail && thread_args[i].result != 0) {
+		if (!err_value && thread_args[i].result != 0) {
 			ksft_print_msg("Thread %d failed (%d)\n", i, thread_args[i].result);
 			need_exit = 1;
 		}
@@ -120,14 +126,14 @@ static void __test_futex(void *futex_ptr, int must_fail, unsigned int futex_flag
 		ksft_exit_fail_msg("Aborting due to earlier errors.\n");
 }
 
-static void test_futex(void *futex_ptr, int must_fail)
+static void test_futex(void *futex_ptr, int err_value)
 {
-	__test_futex(futex_ptr, must_fail, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA);
+	__test_futex(futex_ptr, err_value, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA);
 }
 
-static void test_futex_mpol(void *futex_ptr, int must_fail)
+static void test_futex_mpol(void *futex_ptr, int err_value)
 {
-	__test_futex(futex_ptr, must_fail, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
+	__test_futex(futex_ptr, err_value, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
 }
 
 static void usage(char *prog)
@@ -184,16 +190,16 @@ int main(int argc, char *argv[])
 
 	/* FUTEX2_NUMA futex must be 8-byte aligned */
 	ksft_print_msg("Mis-aligned futex\n");
-	test_futex(futex_ptr + mem_size - 4, 1);
+	test_futex(futex_ptr + mem_size - 4, 22);
 
 	futex_numa->numa = FUTEX_NO_NODE;
 	mprotect(futex_ptr, mem_size, PROT_READ);
 	ksft_print_msg("Memory, RO\n");
-	test_futex(futex_ptr, 1);
+	test_futex(futex_ptr, 14);
 
 	mprotect(futex_ptr, mem_size, PROT_NONE);
 	ksft_print_msg("Memory, no access\n");
-	test_futex(futex_ptr, 1);
+	test_futex(futex_ptr, 14);
 
 	mprotect(futex_ptr, mem_size, PROT_READ | PROT_WRITE);
 	ksft_print_msg("Memory back to RW\n");
-- 
2.51.0