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/sound/usb/pcm.h b/sound/usb/pcm.h
new file mode 100644
index 000000000..c096021ad
--- /dev/null
+++ b/sound/usb/pcm.h
@@ -0,0 +1,29 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __USBAUDIO_PCM_H
+#define __USBAUDIO_PCM_H
+
+void snd_usb_set_pcm_ops(struct snd_pcm *pcm, int stream);
+int snd_usb_pcm_suspend(struct snd_usb_stream *as);
+int snd_usb_pcm_resume(struct snd_usb_stream *as);
+
+bool snd_usb_pcm_has_fixed_rate(struct snd_usb_substream *as);
+
+int snd_usb_init_pitch(struct snd_usb_audio *chip,
+		       const struct audioformat *fmt);
+void snd_usb_preallocate_buffer(struct snd_usb_substream *subs);
+
+int snd_usb_audioformat_set_sync_ep(struct snd_usb_audio *chip,
+				    struct audioformat *fmt);
+
+const struct audioformat *
+snd_usb_find_format(struct list_head *fmt_list_head, snd_pcm_format_t format,
+		    unsigned int rate, unsigned int channels, bool strict_match,
+		    struct snd_usb_substream *subs);
+const struct audioformat *
+snd_usb_find_substream_format(struct snd_usb_substream *subs,
+			      const struct snd_pcm_hw_params *params);
+
+int snd_usb_hw_params(struct snd_usb_substream *subs,
+		      struct snd_pcm_hw_params *hw_params);
+int snd_usb_hw_free(struct snd_usb_substream *subs);
+#endif /* __USBAUDIO_PCM_H */