From 2b97956af60810cd382b86b9ce9aea421b889861 Mon Sep 17 00:00:00 2001 From: Nuoqi Gui Date: Fri, 4 Sep 2026 12:41:55 +0200 Subject: selftests/bpf: Test rhtab kptr cancellation semantics 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 [ kkd: Split update and delete coverage and rewrote the commit log ] Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904104203.345917-5-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- samples/livepatch/livepatch-callbacks-mod.c | 42 +++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) create mode 100644 samples/livepatch/livepatch-callbacks-mod.c (limited to 'samples/livepatch/livepatch-callbacks-mod.c') diff --git a/samples/livepatch/livepatch-callbacks-mod.c b/samples/livepatch/livepatch-callbacks-mod.c new file mode 100644 index 000000000..d1851b471 --- /dev/null +++ b/samples/livepatch/livepatch-callbacks-mod.c @@ -0,0 +1,42 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2017 Joe Lawrence + */ + +/* + * livepatch-callbacks-mod.c - (un)patching callbacks demo support module + * + * + * Purpose + * ------- + * + * Simple module to demonstrate livepatch (un)patching callbacks. + * + * + * Usage + * ----- + * + * This module is not intended to be standalone. See the "Usage" + * section of livepatch-callbacks-demo.c. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include + +static int livepatch_callbacks_mod_init(void) +{ + pr_info("%s\n", __func__); + return 0; +} + +static void livepatch_callbacks_mod_exit(void) +{ + pr_info("%s\n", __func__); +} + +module_init(livepatch_callbacks_mod_init); +module_exit(livepatch_callbacks_mod_exit); +MODULE_DESCRIPTION("Live patching demo for (un)patching callbacks, support module"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1