selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 77 insertions, 0 deletions

diff --git a/drivers/video/backlight/ili9320.h b/drivers/video/backlight/ili9320.h
new file mode 100644
index 000000000..8213cc6e9
--- /dev/null
+++ b/drivers/video/backlight/ili9320.h
@@ -0,0 +1,77 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* drivers/video/backlight/ili9320.h
+ *
+ * ILI9320 LCD controller driver core.
+ *
+ * Copyright 2007 Simtec Electronics
+ *	Ben Dooks <ben@simtec.co.uk>
+ *
+ * http://armlinux.simtec.co.uk/
+*/
+
+/* Holder for register and value pairs. */
+struct ili9320_reg {
+	unsigned short		address;
+	unsigned short		value;
+};
+
+struct ili9320;
+
+struct ili9320_client {
+	const char	*name;
+	int	(*init)(struct ili9320 *ili, struct ili9320_platdata *cfg);
+
+};
+/* Device attached via an SPI bus. */
+struct  ili9320_spi {
+	struct spi_device	*dev;
+	struct spi_message	message;
+	struct spi_transfer	xfer[2];
+
+	unsigned char		id;
+	unsigned char		buffer_addr[4];
+	unsigned char		buffer_data[4];
+};
+
+/* ILI9320 device state. */
+struct ili9320 {
+	union {
+		struct ili9320_spi	spi;	/* SPI attachged device. */
+	} access;				/* Register access method. */
+
+	struct device			*dev;
+	struct lcd_device		*lcd;	/* LCD device we created. */
+	struct ili9320_client		*client;
+	struct ili9320_platdata		*platdata;
+
+	int				 power; /* current power state. */
+	int				 initialised;
+
+	unsigned short			 display1;
+	unsigned short			 power1;
+
+	int (*write)(struct ili9320 *ili, unsigned int reg, unsigned int val);
+};
+
+
+/* ILI9320 register access routines */
+
+extern int ili9320_write(struct ili9320 *ili,
+			 unsigned int reg, unsigned int value);
+
+extern int ili9320_write_regs(struct ili9320 *ili,
+			      const struct ili9320_reg *values,
+			      int nr_values);
+
+/* Device probe */
+
+extern int ili9320_probe_spi(struct spi_device *spi,
+			     struct ili9320_client *cli);
+
+extern void ili9320_remove(struct ili9320 *lcd);
+extern void ili9320_shutdown(struct ili9320 *lcd);
+
+/* PM */
+
+extern int ili9320_suspend(struct ili9320 *lcd);
+extern int ili9320_resume(struct ili9320 *lcd);