Patch set [1] added rcu support for bpf programs. In [1], a rcu pointer is considered to be trusted and not null. This is actually not true in some cases. The rcu pointer could be null, and for non-null rcu pointer, it may have reference count of 0. This small patch set fixed this problem. Patch 1 is the kernel fix. Patch 2 adjusted selftests properly. Patch 3 added documentation for newly-introduced KF_RCU flag. [1] https://lore.kernel.org/all/20221124053201.2372298-1-yhs@xxxxxx/ Changelogs: v1 -> v2: - rcu ptr could be NULL. - non_null_rcu_ptr->rcu_field can be marked as MEM_RCU as well. - Adjust the code to avoid existing error message change. Yonghong Song (3): bpf: Handle MEM_RCU type properly selftests/bpf: Fix rcu_read_lock test with new MEM_RCU semantics docs/bpf: Add KF_RCU documentation Documentation/bpf/kfuncs.rst | 9 +++ include/linux/bpf_verifier.h | 2 +- include/linux/btf.h | 1 + kernel/bpf/helpers.c | 14 +++++ kernel/bpf/verifier.c | 45 ++++++++++----- .../selftests/bpf/progs/rcu_read_lock.c | 55 +++++++++++++++---- 6 files changed, 102 insertions(+), 24 deletions(-) -- 2.30.2
