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, 36 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/tc90522.h b/drivers/media/dvb-frontends/tc90522.h
new file mode 100644
index 000000000..07e3813bf
--- /dev/null
+++ b/drivers/media/dvb-frontends/tc90522.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Toshiba TC90522 Demodulator
+ *
+ * Copyright (C) 2014 Akihiro Tsukada <tskd08@gmail.com>
+ */
+
+/*
+ * The demod has 4 input (2xISDB-T and 2xISDB-S),
+ * and provides independent sub modules for each input.
+ * As the sub modules work in parallel and have the separate i2c addr's,
+ * this driver treats each sub module as one demod device.
+ */
+
+#ifndef TC90522_H
+#define TC90522_H
+
+#include <linux/i2c.h>
+#include <media/dvb_frontend.h>
+
+/* I2C device types */
+#define TC90522_I2C_DEV_SAT "tc90522sat"
+#define TC90522_I2C_DEV_TER "tc90522ter"
+
+struct tc90522_config {
+	/* [OUT] frontend returned by driver */
+	struct dvb_frontend *fe;
+
+	/* [OUT] tuner I2C adapter returned by driver */
+	struct i2c_adapter *tuner_i2c;
+
+	/* [IN] use two separate I2C transactions for one tuner read */
+	bool split_tuner_read_i2c;
+};
+
+#endif /* TC90522_H */