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, 40 insertions, 0 deletions

diff --git a/drivers/ntb/Kconfig b/drivers/ntb/Kconfig
new file mode 100644
index 000000000..df16c755b
--- /dev/null
+++ b/drivers/ntb/Kconfig
@@ -0,0 +1,40 @@
+# SPDX-License-Identifier: GPL-2.0-only
+menuconfig NTB
+	tristate "Non-Transparent Bridge support"
+	depends on PCI
+	help
+	 The PCI-E Non-transparent bridge hardware is a point-to-point PCI-E bus
+	 connecting 2 systems.  When configured, writes to the device's PCI
+	 mapped memory will be mirrored to a buffer on the remote system.  The
+	 ntb Linux driver uses this point-to-point communication as a method to
+	 transfer data from one system to the other.
+
+	 If unsure, say N.
+
+if NTB
+
+config NTB_MSI
+	bool "MSI Interrupt Support"
+	depends on PCI_MSI
+	help
+	 Support using MSI interrupt forwarding instead of (or in addition to)
+	 hardware doorbells. MSI interrupts typically offer lower latency
+	 than doorbells and more MSI interrupts can be made available to
+	 clients. However this requires an extra memory window and support
+	 in the hardware driver for creating the MSI interrupts.
+
+	 If unsure, say N.
+source "drivers/ntb/hw/Kconfig"
+
+source "drivers/ntb/test/Kconfig"
+
+config NTB_TRANSPORT
+	tristate "NTB Transport Client"
+	help
+	 This is a transport driver that enables connected systems to exchange
+	 messages over the ntb hardware.  The transport exposes a queue pair api
+	 to client drivers.
+
+	 If unsure, say N.
+
+endif # NTB