Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linuxgrafted

Pull I3C updates from Alexandre Belloni:
 "A new driver this cycle, for the AMD AXI I3C controller.

  There are also new features such as IBI wakeup support, SETAASA device
  discovery and ACPI support for the the DAA methods, meaning we can now
  communicate with the SPD devices on DDR5 modules.

  New driver:
   - AMD AXI I3C master controller

  Subsystem:
   - I3C Common Command Code (CCC) handling improvements, especially
     around GET CCCs
   - SETAASA device discovery support
   - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as
     well as I2C devices on I3C bus
   - IBI-based wakeup support

  Drivers:
   - dw: SETAASA support
   - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C
     controller support, PIO queue management support for HCI v1.2
   - renesas: improve suspend to RAM support, add runtime PM support"

* tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits)
  i3c: dw: reduce do_daa time if there's no client
  i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller
  i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2
  i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode
  i3c: dw: rename "pclk" to "apb" to match dt-binding
  i3c: dw: make struct dw_i3c_cmd smaller
  i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding
  i3c: renesas: Don't register devices when ENTDAA times out
  i3c: master: dw-i3c-master: fix OD timing for first broadcast
  i3c: mipi-i3c-hci: Advertise IBI wakeup capability
  i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev()
  i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI
  i3c: master: Reject IBI requests from non-IBI-capable devices
  i3c: master: Add helper to query bus wakeup requirements
  i3c: master: Report wakeup events for IBIs
  i3c: master: Support IBI-based wakeup capability
  i3c: master: Fix potential UAF in i3c_device_match()
  i3c: master: Fix potential UAF in i3c_device_uevent()
  i3c: Make dev->desc locking assumptions explicit
  i3c: master: Fix use-after-free of master->this
  ...

1 files changed, 294 insertions, 0 deletions

diff --git a/lib/test_workqueue.c b/lib/test_workqueue.c
new file mode 100644
index 000000000..99e160bd5
--- /dev/null
+++ b/lib/test_workqueue.c
@@ -0,0 +1,294 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Test module for stress and performance analysis of workqueue.
+ *
+ * Benchmarks queue_work() throughput on an unbound workqueue to measure
+ * pool->lock contention under different affinity scope configurations
+ * (e.g., cache vs cache_shard).
+ *
+ * The affinity scope is changed between runs via the workqueue's sysfs
+ * affinity_scope attribute (WQ_SYSFS).
+ *
+ * Copyright (c) 2026 Meta Platforms, Inc. and affiliates
+ * Copyright (c) 2026 Breno Leitao <leitao@debian.org>
+ *
+ */
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/workqueue.h>
+#include <linux/kthread.h>
+#include <linux/moduleparam.h>
+#include <linux/completion.h>
+#include <linux/atomic.h>
+#include <linux/slab.h>
+#include <linux/ktime.h>
+#include <linux/cpumask.h>
+#include <linux/sched.h>
+#include <linux/sort.h>
+#include <linux/fs.h>
+
+#define WQ_NAME "bench_wq"
+#define SCOPE_PATH "/sys/bus/workqueue/devices/" WQ_NAME "/affinity_scope"
+
+static int nr_threads;
+module_param(nr_threads, int, 0444);
+MODULE_PARM_DESC(nr_threads,
+		 "Number of threads to spawn (default: 0 = num_online_cpus())");
+
+static int wq_items = 50000;
+module_param(wq_items, int, 0444);
+MODULE_PARM_DESC(wq_items,
+		 "Number of work items each thread queues (default: 50000)");
+
+static struct workqueue_struct *bench_wq;
+static atomic_t threads_done;
+static DECLARE_COMPLETION(start_comp);
+static DECLARE_COMPLETION(all_done_comp);
+
+struct thread_ctx {
+	struct completion work_done;
+	struct work_struct work;
+	u64 *latencies;
+	int cpu;
+	int items;
+};
+
+static void bench_work_fn(struct work_struct *work)
+{
+	struct thread_ctx *ctx = container_of(work, struct thread_ctx, work);
+
+	complete(&ctx->work_done);
+}
+
+static int bench_kthread_fn(void *data)
+{
+	struct thread_ctx *ctx = data;
+	ktime_t t_start, t_end;
+	int i;
+
+	/* Wait for all threads to be ready */
+	wait_for_completion(&start_comp);
+
+	if (kthread_should_stop())
+		return 0;
+
+	for (i = 0; i < ctx->items; i++) {
+		reinit_completion(&ctx->work_done);
+		INIT_WORK(&ctx->work, bench_work_fn);
+
+		t_start = ktime_get();
+		queue_work(bench_wq, &ctx->work);
+		t_end = ktime_get();
+
+		ctx->latencies[i] = ktime_to_ns(ktime_sub(t_end, t_start));
+		wait_for_completion(&ctx->work_done);
+	}
+
+	if (atomic_dec_and_test(&threads_done))
+		complete(&all_done_comp);
+
+	/*
+	 * Wait for kthread_stop() so the module text isn't freed
+	 * while we're still executing.
+	 */
+	while (!kthread_should_stop())
+		schedule();
+
+	return 0;
+}
+
+static int cmp_u64(const void *a, const void *b)
+{
+	u64 va = *(const u64 *)a;
+	u64 vb = *(const u64 *)b;
+
+	if (va < vb)
+		return -1;
+	if (va > vb)
+		return 1;
+	return 0;
+}
+
+static int __init set_affn_scope(const char *scope)
+{
+	struct file *f;
+	loff_t pos = 0;
+	ssize_t ret;
+
+	f = filp_open(SCOPE_PATH, O_WRONLY, 0);
+	if (IS_ERR(f)) {
+		pr_err("test_workqueue: open %s failed: %ld\n",
+		       SCOPE_PATH, PTR_ERR(f));
+		return PTR_ERR(f);
+	}
+
+	ret = kernel_write(f, scope, strlen(scope), &pos);
+	filp_close(f, NULL);
+
+	if (ret < 0) {
+		pr_err("test_workqueue: write '%s' failed: %zd\n", scope, ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static int __init run_bench(int n_threads, const char *scope, const char *label)
+{
+	struct task_struct **tasks;
+	unsigned long total_items;
+	struct thread_ctx *ctxs;
+	u64 *all_latencies;
+	ktime_t start, end;
+	int cpu, i, j, ret;
+	s64 elapsed_us;
+
+	ret = set_affn_scope(scope);
+	if (ret)
+		return ret;
+
+	ctxs = kcalloc(n_threads, sizeof(*ctxs), GFP_KERNEL);
+	if (!ctxs)
+		return -ENOMEM;
+
+	tasks = kcalloc(n_threads, sizeof(*tasks), GFP_KERNEL);
+	if (!tasks) {
+		kfree(ctxs);
+		return -ENOMEM;
+	}
+
+	total_items = (unsigned long)n_threads * wq_items;
+	all_latencies = kvmalloc_array(total_items, sizeof(u64), GFP_KERNEL);
+	if (!all_latencies) {
+		kfree(tasks);
+		kfree(ctxs);
+		return -ENOMEM;
+	}
+
+	/* Allocate per-thread latency arrays */
+	for (i = 0; i < n_threads; i++) {
+		ctxs[i].latencies = kvmalloc_array(wq_items, sizeof(u64),
+						   GFP_KERNEL);
+		if (!ctxs[i].latencies) {
+			while (--i >= 0)
+				kvfree(ctxs[i].latencies);
+			kvfree(all_latencies);
+			kfree(tasks);
+			kfree(ctxs);
+			return -ENOMEM;
+		}
+	}
+
+	atomic_set(&threads_done, n_threads);
+	reinit_completion(&all_done_comp);
+	reinit_completion(&start_comp);
+
+	/* Create kthreads, each bound to a different online CPU */
+	i = 0;
+	for_each_online_cpu(cpu) {
+		if (i >= n_threads)
+			break;
+
+		ctxs[i].cpu = cpu;
+		ctxs[i].items = wq_items;
+		init_completion(&ctxs[i].work_done);
+
+		tasks[i] = kthread_create(bench_kthread_fn, &ctxs[i],
+					  "wq_bench/%d", cpu);
+		if (IS_ERR(tasks[i])) {
+			ret = PTR_ERR(tasks[i]);
+			pr_err("test_workqueue: failed to create kthread %d: %d\n",
+			       i, ret);
+			/* Unblock threads waiting on start_comp before stopping them */
+			complete_all(&start_comp);
+			while (--i >= 0)
+				kthread_stop(tasks[i]);
+			goto out_free;
+		}
+
+		kthread_bind(tasks[i], cpu);
+		wake_up_process(tasks[i]);
+		i++;
+	}
+
+	/* Start timing and release all threads */
+	start = ktime_get();
+	complete_all(&start_comp);
+
+	/* Wait for all threads to finish the benchmark */
+	wait_for_completion(&all_done_comp);
+
+	/* Drain any remaining work */
+	flush_workqueue(bench_wq);
+
+	/* Ensure all kthreads have fully exited before module memory is freed */
+	for (i = 0; i < n_threads; i++)
+		kthread_stop(tasks[i]);
+
+	end = ktime_get();
+	elapsed_us = ktime_us_delta(end, start);
+
+	/* Merge all per-thread latencies and sort for percentile calculation */
+	j = 0;
+	for (i = 0; i < n_threads; i++) {
+		memcpy(&all_latencies[j], ctxs[i].latencies,
+		       wq_items * sizeof(u64));
+		j += wq_items;
+	}
+
+	sort(all_latencies, total_items, sizeof(u64), cmp_u64, NULL);
+
+	pr_info("test_workqueue:   %-16s %llu items/sec\tp50=%llu\tp90=%llu\tp95=%llu ns\n",
+		label,
+		elapsed_us ? div_u64(total_items * 1000000ULL, elapsed_us) : 0,
+		all_latencies[total_items * 50 / 100],
+		all_latencies[total_items * 90 / 100],
+		all_latencies[total_items * 95 / 100]);
+
+	ret = 0;
+out_free:
+	for (i = 0; i < n_threads; i++)
+		kvfree(ctxs[i].latencies);
+	kvfree(all_latencies);
+	kfree(tasks);
+	kfree(ctxs);
+
+	return ret;
+}
+
+static const char * const bench_scopes[] = {
+	"cpu", "smt", "cache_shard", "cache", "numa", "system",
+};
+
+static int __init test_workqueue_init(void)
+{
+	int n_threads = min(nr_threads ?: num_online_cpus(), num_online_cpus());
+	int i;
+
+	if (wq_items <= 0) {
+		pr_err("test_workqueue: wq_items must be > 0\n");
+		return -EINVAL;
+	}
+
+	bench_wq = alloc_workqueue(WQ_NAME, WQ_UNBOUND | WQ_SYSFS, 0);
+	if (!bench_wq)
+		return -ENOMEM;
+
+	pr_info("test_workqueue: running %d threads, %d items/thread\n",
+		n_threads, wq_items);
+
+	for (i = 0; i < ARRAY_SIZE(bench_scopes); i++)
+		run_bench(n_threads, bench_scopes[i], bench_scopes[i]);
+
+	destroy_workqueue(bench_wq);
+
+	/* Return -EAGAIN so the module doesn't stay loaded after the benchmark */
+	return -EAGAIN;
+}
+
+module_init(test_workqueue_init);
+MODULE_AUTHOR("Breno Leitao <leitao@debian.org>");
+MODULE_DESCRIPTION("Stress/performance benchmark for workqueue subsystem");
+MODULE_LICENSE("GPL");