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, 228 insertions, 0 deletions

diff --git a/include/trace/events/objagg.h b/include/trace/events/objagg.h
new file mode 100644
index 000000000..fcec0fc9e
--- /dev/null
+++ b/include/trace/events/objagg.h
@@ -0,0 +1,228 @@
+/* SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 */
+/* Copyright (c) 2018 Mellanox Technologies. All rights reserved */
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM objagg
+
+#if !defined(__TRACE_OBJAGG_H) || defined(TRACE_HEADER_MULTI_READ)
+#define __TRACE_OBJAGG_H
+
+#include <linux/tracepoint.h>
+
+struct objagg;
+struct objagg_obj;
+
+TRACE_EVENT(objagg_create,
+	TP_PROTO(const struct objagg *objagg),
+
+	TP_ARGS(objagg),
+
+	TP_STRUCT__entry(
+		__field(const void *, objagg)
+	),
+
+	TP_fast_assign(
+		__entry->objagg = objagg;
+	),
+
+	TP_printk("objagg %p", __entry->objagg)
+);
+
+TRACE_EVENT(objagg_destroy,
+	TP_PROTO(const struct objagg *objagg),
+
+	TP_ARGS(objagg),
+
+	TP_STRUCT__entry(
+		__field(const void *, objagg)
+	),
+
+	TP_fast_assign(
+		__entry->objagg = objagg;
+	),
+
+	TP_printk("objagg %p", __entry->objagg)
+);
+
+TRACE_EVENT(objagg_obj_create,
+	TP_PROTO(const struct objagg *objagg,
+		 const struct objagg_obj *obj),
+
+	TP_ARGS(objagg, obj),
+
+	TP_STRUCT__entry(
+		__field(const void *, objagg)
+		__field(const void *, obj)
+	),
+
+	TP_fast_assign(
+		__entry->objagg = objagg;
+		__entry->obj = obj;
+	),
+
+	TP_printk("objagg %p, obj %p", __entry->objagg, __entry->obj)
+);
+
+TRACE_EVENT(objagg_obj_destroy,
+	TP_PROTO(const struct objagg *objagg,
+		 const struct objagg_obj *obj),
+
+	TP_ARGS(objagg, obj),
+
+	TP_STRUCT__entry(
+		__field(const void *, objagg)
+		__field(const void *, obj)
+	),
+
+	TP_fast_assign(
+		__entry->objagg = objagg;
+		__entry->obj = obj;
+	),
+
+	TP_printk("objagg %p, obj %p", __entry->objagg, __entry->obj)
+);
+
+TRACE_EVENT(objagg_obj_get,
+	TP_PROTO(const struct objagg *objagg,
+		 const struct objagg_obj *obj,
+		 unsigned int refcount),
+
+	TP_ARGS(objagg, obj, refcount),
+
+	TP_STRUCT__entry(
+		__field(const void *, objagg)
+		__field(const void *, obj)
+		__field(unsigned int, refcount)
+	),
+
+	TP_fast_assign(
+		__entry->objagg = objagg;
+		__entry->obj = obj;
+		__entry->refcount = refcount;
+	),
+
+	TP_printk("objagg %p, obj %p, refcount %u",
+		  __entry->objagg, __entry->obj, __entry->refcount)
+);
+
+TRACE_EVENT(objagg_obj_put,
+	TP_PROTO(const struct objagg *objagg,
+		 const struct objagg_obj *obj,
+		 unsigned int refcount),
+
+	TP_ARGS(objagg, obj, refcount),
+
+	TP_STRUCT__entry(
+		__field(const void *, objagg)
+		__field(const void *, obj)
+		__field(unsigned int, refcount)
+	),
+
+	TP_fast_assign(
+		__entry->objagg = objagg;
+		__entry->obj = obj;
+		__entry->refcount = refcount;
+	),
+
+	TP_printk("objagg %p, obj %p, refcount %u",
+		  __entry->objagg, __entry->obj, __entry->refcount)
+);
+
+TRACE_EVENT(objagg_obj_parent_assign,
+	TP_PROTO(const struct objagg *objagg,
+		 const struct objagg_obj *obj,
+		 const struct objagg_obj *parent,
+		 unsigned int parent_refcount),
+
+	TP_ARGS(objagg, obj, parent, parent_refcount),
+
+	TP_STRUCT__entry(
+		__field(const void *, objagg)
+		__field(const void *, obj)
+		__field(const void *, parent)
+		__field(unsigned int, parent_refcount)
+	),
+
+	TP_fast_assign(
+		__entry->objagg = objagg;
+		__entry->obj = obj;
+		__entry->parent = parent;
+		__entry->parent_refcount = parent_refcount;
+	),
+
+	TP_printk("objagg %p, obj %p, parent %p, parent_refcount %u",
+		  __entry->objagg, __entry->obj,
+		  __entry->parent, __entry->parent_refcount)
+);
+
+TRACE_EVENT(objagg_obj_parent_unassign,
+	TP_PROTO(const struct objagg *objagg,
+		 const struct objagg_obj *obj,
+		 const struct objagg_obj *parent,
+		 unsigned int parent_refcount),
+
+	TP_ARGS(objagg, obj, parent, parent_refcount),
+
+	TP_STRUCT__entry(
+		__field(const void *, objagg)
+		__field(const void *, obj)
+		__field(const void *, parent)
+		__field(unsigned int, parent_refcount)
+	),
+
+	TP_fast_assign(
+		__entry->objagg = objagg;
+		__entry->obj = obj;
+		__entry->parent = parent;
+		__entry->parent_refcount = parent_refcount;
+	),
+
+	TP_printk("objagg %p, obj %p, parent %p, parent_refcount %u",
+		  __entry->objagg, __entry->obj,
+		  __entry->parent, __entry->parent_refcount)
+);
+
+TRACE_EVENT(objagg_obj_root_create,
+	TP_PROTO(const struct objagg *objagg,
+		 const struct objagg_obj *obj),
+
+	TP_ARGS(objagg, obj),
+
+	TP_STRUCT__entry(
+		__field(const void *, objagg)
+		__field(const void *, obj)
+	),
+
+	TP_fast_assign(
+		__entry->objagg = objagg;
+		__entry->obj = obj;
+	),
+
+	TP_printk("objagg %p, obj %p",
+		  __entry->objagg, __entry->obj)
+);
+
+TRACE_EVENT(objagg_obj_root_destroy,
+	TP_PROTO(const struct objagg *objagg,
+		 const struct objagg_obj *obj),
+
+	TP_ARGS(objagg, obj),
+
+	TP_STRUCT__entry(
+		__field(const void *, objagg)
+		__field(const void *, obj)
+	),
+
+	TP_fast_assign(
+		__entry->objagg = objagg;
+		__entry->obj = obj;
+	),
+
+	TP_printk("objagg %p, obj %p",
+		  __entry->objagg, __entry->obj)
+);
+
+#endif /* __TRACE_OBJAGG_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>