selftests/bpf: Test rhtab kptr cancellation semanticsgrafted

Resizable hash-map updates and deletions must not perform full special-field
destruction in their caller context. In particular, a referenced kptr must
remain attached to the allocation until the memory allocator destructor can
release it safely.

Add separate coverage for both affected paths. The update test stores a task
kptr, replaces the ordinary value bytes with BPF_EXIST, and verifies that the
kptr survived. The delete test removes an element and exchanges its kptr
through the still-valid map-value pointer before the allocation is reclaimed.

Both cases observe a NULL kptr when rhtab uses bpf_obj_free_fields(). They
recover and release the reference after rhtab switches to cancellation
semantics.

Signed-off-by: Nuoqi Gui <gnq25@mails.tsinghua.edu.cn>
[ kkd: Split update and delete coverage and rewrote the commit log ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904104203.345917-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 134 insertions, 0 deletions

diff --git a/drivers/input/misc/pcspkr.c b/drivers/input/misc/pcspkr.c
new file mode 100644
index 000000000..046780840
--- /dev/null
+++ b/drivers/input/misc/pcspkr.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  PC Speaker beeper driver for Linux
+ *
+ *  Copyright (c) 2002 Vojtech Pavlik
+ *  Copyright (c) 1992 Orest Zborowski
+ */
+
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/i8253.h>
+#include <linux/input.h>
+#include <linux/platform_device.h>
+#include <linux/timex.h>
+#include <linux/io.h>
+
+MODULE_AUTHOR("Vojtech Pavlik <vojtech@ucw.cz>");
+MODULE_DESCRIPTION("PC Speaker beeper driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:pcspkr");
+
+static int pcspkr_event(struct input_dev *dev, unsigned int type,
+			unsigned int code, int value)
+{
+	unsigned int count = 0;
+	unsigned long flags;
+
+	if (type != EV_SND)
+		return -EINVAL;
+
+	switch (code) {
+	case SND_BELL:
+		if (value)
+			value = 1000;
+		break;
+	case SND_TONE:
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	if (value > 20 && value < 32767)
+		count = PIT_TICK_RATE / value;
+
+	raw_spin_lock_irqsave(&i8253_lock, flags);
+
+	if (count) {
+		/* set command for counter 2, 2 byte write */
+		outb_p(0xB6, 0x43);
+		/* select desired HZ */
+		outb_p(count & 0xff, 0x42);
+		outb((count >> 8) & 0xff, 0x42);
+		/* enable counter 2 */
+		outb_p(inb_p(0x61) | 3, 0x61);
+	} else {
+		/* disable counter 2 */
+		outb(inb_p(0x61) & 0xFC, 0x61);
+	}
+
+	raw_spin_unlock_irqrestore(&i8253_lock, flags);
+
+	return 0;
+}
+
+static int pcspkr_probe(struct platform_device *dev)
+{
+	struct input_dev *pcspkr_dev;
+	int err;
+
+	pcspkr_dev = input_allocate_device();
+	if (!pcspkr_dev)
+		return -ENOMEM;
+
+	pcspkr_dev->name = "PC Speaker";
+	pcspkr_dev->phys = "isa0061/input0";
+	pcspkr_dev->id.bustype = BUS_ISA;
+	pcspkr_dev->id.vendor = 0x001f;
+	pcspkr_dev->id.product = 0x0001;
+	pcspkr_dev->id.version = 0x0100;
+	pcspkr_dev->dev.parent = &dev->dev;
+
+	pcspkr_dev->evbit[0] = BIT_MASK(EV_SND);
+	pcspkr_dev->sndbit[0] = BIT_MASK(SND_BELL) | BIT_MASK(SND_TONE);
+	pcspkr_dev->event = pcspkr_event;
+
+	err = input_register_device(pcspkr_dev);
+	if (err) {
+		input_free_device(pcspkr_dev);
+		return err;
+	}
+
+	platform_set_drvdata(dev, pcspkr_dev);
+
+	return 0;
+}
+
+static void pcspkr_remove(struct platform_device *dev)
+{
+	struct input_dev *pcspkr_dev = platform_get_drvdata(dev);
+
+	input_unregister_device(pcspkr_dev);
+	/* turn off the speaker */
+	pcspkr_event(NULL, EV_SND, SND_BELL, 0);
+}
+
+static int pcspkr_suspend(struct device *dev)
+{
+	pcspkr_event(NULL, EV_SND, SND_BELL, 0);
+
+	return 0;
+}
+
+static void pcspkr_shutdown(struct platform_device *dev)
+{
+	/* turn off the speaker */
+	pcspkr_event(NULL, EV_SND, SND_BELL, 0);
+}
+
+static const struct dev_pm_ops pcspkr_pm_ops = {
+	.suspend = pcspkr_suspend,
+};
+
+static struct platform_driver pcspkr_platform_driver = {
+	.driver		= {
+		.name	= "pcspkr",
+		.pm	= &pcspkr_pm_ops,
+	},
+	.probe		= pcspkr_probe,
+	.remove		= pcspkr_remove,
+	.shutdown	= pcspkr_shutdown,
+};
+module_platform_driver(pcspkr_platform_driver);
+