selftests/bpf: Test rhtab kptr cancellation semanticsgrafted

Resizable hash-map updates and deletions must not perform full special-field
destruction in their caller context. In particular, a referenced kptr must
remain attached to the allocation until the memory allocator destructor can
release it safely.

Add separate coverage for both affected paths. The update test stores a task
kptr, replaces the ordinary value bytes with BPF_EXIST, and verifies that the
kptr survived. The delete test removes an element and exchanges its kptr
through the still-valid map-value pointer before the allocation is reclaimed.

Both cases observe a NULL kptr when rhtab uses bpf_obj_free_fields(). They
recover and release the reference after rhtab switches to cancellation
semantics.

Signed-off-by: Nuoqi Gui <gnq25@mails.tsinghua.edu.cn>
[ kkd: Split update and delete coverage and rewrote the commit log ]
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904104203.345917-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 22 insertions, 0 deletions

diff --git a/tools/memory-model/linux-kernel.cfg b/tools/memory-model/linux-kernel.cfg
new file mode 100644
index 000000000..69b04f3aa
--- /dev/null
+++ b/tools/memory-model/linux-kernel.cfg
@@ -0,0 +1,22 @@
+macros linux-kernel.def
+bell linux-kernel.bell
+model linux-kernel.cat
+variant lkmmv2
+graph columns
+squished true
+showevents noregs
+movelabel true
+fontsize 8
+xscale 2.0
+yscale 1.5
+arrowsize 0.8
+showinitrf false
+showfinalrf false
+showinitwrites false
+splines spline
+pad 0.1
+edgeattr hb,color,indigo
+edgeattr co,color,blue
+edgeattr mb,color,darkgreen
+edgeattr wmb,color,darkgreen
+edgeattr rmb,color,darkgreen