Merge tag 'locking-futex-2025-12-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull futex updates from Ingo Molnar:

 - Standardize on ktime_t in restart_block::time as well (Thomas
   Weißschuh)

 - Futex selftests:
     - Add robust list testcases (André Almeida)
     - Formatting fixes/cleanups (Carlos Llamas)

* tag 'locking-futex-2025-12-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Store time as ktime_t in restart block
  selftests/futex: Create test for robust list
  selftests/futex: Skip tests if shmget unsupported
  selftests/futex: Add newline to ksft_exit_fail_msg()
  selftests/futex: Remove unused test_futex_mpol()

Author: torvalds

include/linux/restart_block.h

@@ -32,7 +32,7 @@ struct restart_block {
 			u32 val;
 			u32 flags;
 			u32 bitset;
-			u64 time;
+			ktime_t time;
 			u32 __user *uaddr2;
 		} futex;
 		/* For nanosleep */

kernel/futex/waitwake.c

@@ -738,12 +738,11 @@ int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time
 static long futex_wait_restart(struct restart_block *restart)
 {
 	u32 __user *uaddr = restart->futex.uaddr;
-	ktime_t t, *tp = NULL;
+	ktime_t *tp = NULL;
+
+	if (restart->futex.flags & FLAGS_HAS_TIMEOUT)
+		tp = &restart->futex.time;
 
-	if (restart->futex.flags & FLAGS_HAS_TIMEOUT) {
-		t = restart->futex.time;
-		tp = &t;
-	}
 	restart->fn = do_no_restart_syscall;
 
 	return (long)futex_wait(uaddr, restart->futex.flags,

tools/testing/selftests/futex/functional/.gitignore

@@ -12,3 +12,4 @@ futex_wait_uninitialized_heap
 futex_wait_wouldblock
 futex_waitv
 futex_numa
+robust_list

tools/testing/selftests/futex/functional/Makefile

@@ -22,7 +22,8 @@ TEST_GEN_PROGS := \
 	futex_priv_hash \
 	futex_numa_mpol \
 	futex_waitv \
-	futex_numa
+	futex_numa \
+	robust_list
 
 TEST_PROGS := run.sh
 

tools/testing/selftests/futex/functional/futex_numa_mpol.c

@@ -131,11 +131,6 @@ static void test_futex(void *futex_ptr, int err_value)
 	__test_futex(futex_ptr, err_value, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA);
 }
 
-static void test_futex_mpol(void *futex_ptr, int err_value)
-{
-	__test_futex(futex_ptr, err_value, FUTEX2_SIZE_U32 | FUTEX_PRIVATE_FLAG | FUTEX2_NUMA | FUTEX2_MPOL);
-}
-
 TEST(futex_numa_mpol)
 {
 	struct futex32_numa *futex_numa;

tools/testing/selftests/futex/functional/futex_wait.c

@@ -71,6 +71,8 @@ TEST(anon_page)
 	/* Testing an anon page shared memory */
 	shm_id = shmget(IPC_PRIVATE, 4096, IPC_CREAT | 0666);
 	if (shm_id < 0) {
+		if (errno == ENOSYS)
+			ksft_exit_skip("shmget syscall not supported\n");
 		perror("shmget");
 		exit(1);
 	}
@@ -108,14 +110,14 @@ TEST(file_backed)
 	/* Testing a file backed shared memory */
 	fd = open(SHM_PATH, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
 	if (fd < 0)
-		ksft_exit_fail_msg("open");
+		ksft_exit_fail_msg("open\n");
 
 	if (ftruncate(fd, sizeof(f_private)))
-		ksft_exit_fail_msg("ftruncate");
+		ksft_exit_fail_msg("ftruncate\n");
 
 	shm = mmap(NULL, sizeof(f_private), PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
 	if (shm == MAP_FAILED)
-		ksft_exit_fail_msg("mmap");
+		ksft_exit_fail_msg("mmap\n");
 
 	memcpy(shm, &f_private, sizeof(f_private));
 

tools/testing/selftests/futex/functional/futex_waitv.c

@@ -86,6 +86,8 @@ TEST(shared_waitv)
 		int shm_id = shmget(IPC_PRIVATE, 4096, IPC_CREAT | 0666);
 
 		if (shm_id < 0) {
+			if (errno == ENOSYS)
+				ksft_exit_skip("shmget syscall not supported\n");
 			perror("shmget");
 			exit(1);
 		}