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, 29 insertions, 0 deletions

diff --git a/drivers/media/dvb-frontends/a8293.h b/drivers/media/dvb-frontends/a8293.h
new file mode 100644
index 000000000..7fbac9735
--- /dev/null
+++ b/drivers/media/dvb-frontends/a8293.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Allegro A8293 SEC driver
+ *
+ * Copyright (C) 2011 Antti Palosaari <crope@iki.fi>
+ */
+
+#ifndef A8293_H
+#define A8293_H
+
+#include <media/dvb_frontend.h>
+
+/*
+ * I2C address
+ * 0x08, 0x09, 0x0a, 0x0b
+ */
+
+/**
+ * struct a8293_platform_data - Platform data for the a8293 driver
+ * @dvb_frontend: DVB frontend.
+ * @volt_slew_nanos_per_mv: Slew rate when increasing LNB voltage,
+ *	 in nanoseconds per millivolt.
+ */
+struct a8293_platform_data {
+	struct dvb_frontend *dvb_frontend;
+	int volt_slew_nanos_per_mv;
+};
+
+#endif /* A8293_H */