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, 38 insertions, 0 deletions

diff --git a/drivers/clk/clk.h b/drivers/clk/clk.h
new file mode 100644
index 000000000..2d801900c
--- /dev/null
+++ b/drivers/clk/clk.h
@@ -0,0 +1,38 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2013 Samsung Electronics Co., Ltd.
+ * Sylwester Nawrocki <s.nawrocki@samsung.com>
+ */
+
+struct clk_hw;
+struct device;
+struct of_phandle_args;
+
+#if defined(CONFIG_OF) && defined(CONFIG_COMMON_CLK)
+struct clk_hw *of_clk_get_hw(struct device_node *np,
+				    int index, const char *con_id);
+#else /* !CONFIG_COMMON_CLK || !CONFIG_OF */
+static inline struct clk_hw *of_clk_get_hw(struct device_node *np,
+				    int index, const char *con_id)
+{
+	return ERR_PTR(-ENOENT);
+}
+#endif
+
+struct clk_hw *clk_find_hw(const char *dev_id, const char *con_id);
+
+#ifdef CONFIG_COMMON_CLK
+struct clk *clk_hw_create_clk(struct device *dev, struct clk_hw *hw,
+			      const char *dev_id, const char *con_id);
+void __clk_put(struct clk *clk);
+#else
+/* All these casts to avoid ifdefs in clkdev... */
+static inline struct clk *
+clk_hw_create_clk(struct device *dev, struct clk_hw *hw, const char *dev_id,
+		  const char *con_id)
+{
+	return (struct clk *)hw;
+}
+static inline void __clk_put(struct clk *clk) { }
+
+#endif