+ kunit-add-tests-for-smp_cond_load_relaxed_timeout.patch added to mm-new branch

+ kunit-add-tests-for-smp_cond_load_relaxed_timeout.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: kunit: add tests for smp_cond_load_relaxed_timeout()
has been added to the -mm mm-new branch.  Its filename is
     kunit-add-tests-for-smp_cond_load_relaxed_timeout.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/kunit-add-tests-for-smp_cond_load_relaxed_timeout.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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------------------------------------------------------
From: Ankur Arora <ankur.a.arora@oracle.com>
Subject: kunit: add tests for smp_cond_load_relaxed_timeout()
Date: Wed, 8 Apr 2026 17:55:38 +0530

Add a success and failure case for smp_cond_load_relaxed_timeout().

Both test cases wait on some state in smp_cond_load_relaxed_timeout().  In
the success case we spawn a kthread that pokes the bit.

Link: https://lore.kernel.org/20260408122538.3610871-15-ankur.a.arora@oracle.com
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: David Gow <davidgow@google.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Haris Okanovic <harisokn@amazon.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Konrad Dybcio <konradybcio@kernel.org>
Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki (Intel) <rafael@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/Kconfig.debug                |   10 ++
 lib/tests/Makefile               |    1 
 lib/tests/barrier-timeout-test.c |  125 +++++++++++++++++++++++++++++
 3 files changed, 136 insertions(+)

--- a/lib/Kconfig.debug~kunit-add-tests-for-smp_cond_load_relaxed_timeout
+++ a/lib/Kconfig.debug
@@ -2406,6 +2406,16 @@ config FPROBE_SANITY_TEST
 
 	  Say N if you are unsure.
 
+config BARRIER_TIMEOUT_TEST
+	tristate "KUnit tests for smp_cond_load_relaxed_timeout()"
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
+	help
+	  Builds KUnit tests that validate wake-up and timeout handling paths
+	  in smp_cond_load_relaxed_timeout().
+
+	  Say N if you are unsure.
+
 config BACKTRACE_SELF_TEST
 	tristate "Self test for the backtrace code"
 	depends on DEBUG_KERNEL
diff --git a/lib/tests/barrier-timeout-test.c a/lib/tests/barrier-timeout-test.c
new file mode 100644
--- /dev/null
+++ a/lib/tests/barrier-timeout-test.c
@@ -0,0 +1,125 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * KUnit tests exercising smp_cond_load_relaxed_timeout().
+ *
+ * Copyright (c) 2026, Oracle Corp.
+ * Author: Ankur Arora <ankur.a.arora@oracle.com>
+ */
+
+#include <linux/bitops.h>
+#include <linux/types.h>
+#include <linux/sched/clock.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <asm/barrier.h>
+#include <kunit/test.h>
+#include <kunit/visibility.h>
+
+MODULE_IMPORT_NS("EXPORTED_FOR_KUNIT_TESTING");
+
+struct clock_state {
+	s64 start_time;
+	s64 end_time;
+};
+
+#define TIMEOUT_MSEC	2
+#define TEST_FLAG_VAL	BIT(2)
+static unsigned int flag;
+
+static s64 basic_clock(struct clock_state *clk)
+{
+	clk->end_time = local_clock();
+	return clk->end_time;
+}
+
+static void update_flags(void)
+{
+	WRITE_ONCE(flag, TEST_FLAG_VAL);
+}
+
+static s64 mock_clock(struct clock_state *clk)
+{
+	s64 clk_mid = clk->start_time + (TIMEOUT_MSEC * NSEC_PER_MSEC)/2;
+
+	clk->end_time = local_clock();
+	if (clk->end_time >= clk_mid)
+		update_flags();
+	return clk->end_time;
+}
+
+typedef s64 (*clkfn_t)(struct clock_state *);
+
+static void test_smp_cond_relaxed_timeout(struct kunit *test,
+					  clkfn_t clock, bool succeeds)
+{
+	struct clock_state clk = {
+		.start_time = local_clock(),
+		.end_time = local_clock(),
+	};
+	s64 runtime, timeout_ns = TIMEOUT_MSEC * NSEC_PER_MSEC;
+	unsigned int result;
+
+	result = smp_cond_load_relaxed_timeout(&flag,
+					       (VAL & TEST_FLAG_VAL),
+					       clock(&clk),
+					       timeout_ns);
+
+	runtime = clk.end_time - clk.start_time;
+	KUNIT_EXPECT_EQ(test, (bool)(result & TEST_FLAG_VAL), succeeds);
+	KUNIT_EXPECT_EQ(test, runtime <= timeout_ns, succeeds);
+}
+
+static int smp_cond_threadfn(void *data)
+{
+	udelay(TIMEOUT_MSEC * USEC_PER_MSEC / 4);
+
+	/*
+	 * Update flags after a delay to give smp_cond_relaxed_timeout()
+	 * time to get started.
+	 */
+	update_flags();
+	return 0;
+}
+
+static void smp_cond_relaxed_timeout_succeeds(struct kunit *test)
+{
+	struct task_struct *task;
+
+	flag = 0;
+
+	task = kthread_run(smp_cond_threadfn, &flag, "smp_cond_thread");
+
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, task);
+	test_smp_cond_relaxed_timeout(test, &basic_clock, true);
+
+	kthread_stop(task);
+}
+
+static void smp_cond_relaxed_timeout_mocked(struct kunit *test)
+{
+	flag = 0;
+	test_smp_cond_relaxed_timeout(test, &mock_clock, true);
+}
+
+static void smp_cond_relaxed_timeout_expires(struct kunit *test)
+{
+	flag = 0;
+	test_smp_cond_relaxed_timeout(test, &basic_clock, false);
+}
+
+static struct kunit_case barrier_timeout_test_cases[] = {
+	KUNIT_CASE(smp_cond_relaxed_timeout_mocked),
+	KUNIT_CASE(smp_cond_relaxed_timeout_succeeds),
+	KUNIT_CASE(smp_cond_relaxed_timeout_expires),
+	{}
+};
+
+static struct kunit_suite barrier_timeout_test_suite = {
+	.name = "smp-cond-load-relaxed-timeout",
+	.test_cases = barrier_timeout_test_cases,
+};
+
+kunit_test_suite(barrier_timeout_test_suite);
+
+MODULE_DESCRIPTION("KUnit tests for smp_cond_load_relaxed_timeout()");
+MODULE_LICENSE("GPL");
--- a/lib/tests/Makefile~kunit-add-tests-for-smp_cond_load_relaxed_timeout
+++ a/lib/tests/Makefile
@@ -20,6 +20,7 @@ CFLAGS_fortify_kunit.o += $(DISABLE_STRU
 obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o
 CFLAGS_test_fprobe.o += $(CC_FLAGS_FTRACE)
 obj-$(CONFIG_FPROBE_SANITY_TEST) += test_fprobe.o
+obj-$(CONFIG_BARRIER_TIMEOUT_TEST) += barrier-timeout-test.o
 obj-$(CONFIG_GLOB_KUNIT_TEST) += glob_kunit.o
 obj-$(CONFIG_HASHTABLE_KUNIT_TEST) += hashtable_test.o
 obj-$(CONFIG_HASH_KUNIT_TEST) += test_hash.o
_

Patches currently in -mm which might be from ankur.a.arora@oracle.com are

asm-generic-barrier-add-smp_cond_load_relaxed_timeout.patch
arm64-barrier-support-smp_cond_load_relaxed_timeout.patch
arm64-delay-move-some-constants-out-to-a-separate-header.patch
arm64-support-wfet-in-smp_cond_load_relaxed_timeout.patch
arm64-rqspinlock-remove-private-copy-of-smp_cond_load_acquire_timewait.patch
asm-generic-barrier-add-smp_cond_load_acquire_timeout.patch
atomic-add-atomic_cond_read__timeout.patch
locking-atomic-scripts-build-atomic_long_cond_read__timeout.patch
bpf-rqspinlock-switch-check_timeout-to-a-clock-interface.patch
bpf-rqspinlock-use-smp_cond_load_acquire_timeout.patch
sched-add-need-resched-timed-wait-interface.patch
cpuidle-poll_state-wait-for-need-resched-via-tif_need_resched_relaxed_wait.patch
kunit-enable-testing-smp_cond_load_relaxed_timeout.patch
kunit-add-tests-for-smp_cond_load_relaxed_timeout.patch