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, 73 insertions, 0 deletions

diff --git a/fs/smb/server/stats.h b/fs/smb/server/stats.h
new file mode 100644
index 000000000..b60c30c69
--- /dev/null
+++ b/fs/smb/server/stats.h
@@ -0,0 +1,73 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2025, LG Electronics.
+ *   Author(s): Hyunchul Lee <hyc.lee@gmail.com>
+ *   Copyright (C) 2025, Samsung Electronics.
+ *   Author(s): Vedansh Bhardwaj <v.bhardwaj@samsung.com>
+ */
+
+#ifndef __KSMBD_STATS_H__
+#define __KSMBD_STATS_H__
+
+#define KSMBD_COUNTER_MAX_REQS	19
+
+enum {
+	KSMBD_COUNTER_SESSIONS = 0,
+	KSMBD_COUNTER_TREE_CONNS,
+	KSMBD_COUNTER_REQUESTS,
+	KSMBD_COUNTER_READ_BYTES,
+	KSMBD_COUNTER_WRITE_BYTES,
+	KSMBD_COUNTER_FIRST_REQ,
+	KSMBD_COUNTER_LAST_REQ = KSMBD_COUNTER_FIRST_REQ +
+				KSMBD_COUNTER_MAX_REQS - 1,
+	KSMBD_COUNTER_MAX,
+};
+
+#ifdef CONFIG_PROC_FS
+extern struct ksmbd_counters ksmbd_counters;
+
+struct ksmbd_counters {
+	struct percpu_counter	counters[KSMBD_COUNTER_MAX];
+};
+
+static inline void ksmbd_counter_inc(int type)
+{
+	percpu_counter_inc(&ksmbd_counters.counters[type]);
+}
+
+static inline void ksmbd_counter_dec(int type)
+{
+	percpu_counter_dec(&ksmbd_counters.counters[type]);
+}
+
+static inline void ksmbd_counter_add(int type, s64 value)
+{
+	percpu_counter_add(&ksmbd_counters.counters[type], value);
+}
+
+static inline void ksmbd_counter_sub(int type, s64 value)
+{
+	percpu_counter_sub(&ksmbd_counters.counters[type], value);
+}
+
+static inline void ksmbd_counter_inc_reqs(unsigned int cmd)
+{
+	if (cmd < KSMBD_COUNTER_MAX_REQS)
+		percpu_counter_inc(&ksmbd_counters.counters[KSMBD_COUNTER_FIRST_REQ + cmd]);
+}
+
+static inline s64 ksmbd_counter_sum(int type)
+{
+	return percpu_counter_sum_positive(&ksmbd_counters.counters[type]);
+}
+#else
+
+static inline void ksmbd_counter_inc(int type) {}
+static inline void ksmbd_counter_dec(int type) {}
+static inline void ksmbd_counter_add(int type, s64 value) {}
+static inline void ksmbd_counter_sub(int type, s64 value) {}
+static inline void ksmbd_counter_inc_reqs(unsigned int cmd) {}
+static inline s64 ksmbd_counter_sum(int type) { return 0; }
+#endif
+
+#endif