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, 53 insertions, 0 deletions

diff --git a/sound/usb/6fire/control.h b/sound/usb/6fire/control.h
new file mode 100644
index 000000000..ae57704d9
--- /dev/null
+++ b/sound/usb/6fire/control.h
@@ -0,0 +1,53 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Linux driver for TerraTec DMX 6Fire USB
+ *
+ * Author:	Torsten Schenk <torsten.schenk@zoho.com>
+ * Created:	Jan 01, 2011
+ * Copyright:	(C) Torsten Schenk
+ */
+
+#ifndef USB6FIRE_CONTROL_H
+#define USB6FIRE_CONTROL_H
+
+#include "common.h"
+
+enum {
+	CONTROL_MAX_ELEMENTS = 32
+};
+
+enum {
+	CONTROL_RATE_44KHZ,
+	CONTROL_RATE_48KHZ,
+	CONTROL_RATE_88KHZ,
+	CONTROL_RATE_96KHZ,
+	CONTROL_RATE_176KHZ,
+	CONTROL_RATE_192KHZ,
+	CONTROL_N_RATES
+};
+
+struct control_runtime {
+	int (*update_streaming)(struct control_runtime *rt);
+	int (*set_rate)(struct control_runtime *rt, int rate);
+	int (*set_channels)(struct control_runtime *rt, int n_analog_out,
+		int n_analog_in, bool spdif_out, bool spdif_in);
+
+	struct sfire_chip *chip;
+
+	struct snd_kcontrol *element[CONTROL_MAX_ELEMENTS];
+	bool opt_coax_switch;
+	bool line_phono_switch;
+	bool digital_thru_switch;
+	bool usb_streaming;
+	u8 output_vol[6];
+	u8 ovol_updated;
+	u8 output_mute;
+	s8 input_vol[2];
+	u8 ivol_updated;
+};
+
+int usb6fire_control_init(struct sfire_chip *chip);
+void usb6fire_control_abort(struct sfire_chip *chip);
+void usb6fire_control_destroy(struct sfire_chip *chip);
+#endif /* USB6FIRE_CONTROL_H */
+