[PATCH v8 net-next 13/15] net: Use nested-BH locking for bpf_scratchpad.
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: 2024-06-19 07:23:28
Also in:
bpf, lkml
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [networking] (tcx & tc bpf, sock_addr), networking [general], the rest · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
bpf_scratchpad is a per-CPU variable and relies on disabled BH for its locking. Without per-CPU locking in local_bh_disable() on PREEMPT_RT this data structure requires explicit locking. Add a local_lock_t to the data structure and use local_lock_nested_bh() for locking. This change adds only lockdep coverage and does not alter the functional behaviour for !PREEMPT_RT. Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Hao Luo <redacted> Cc: Jiri Olsa <jolsa@kernel.org> Cc: John Fastabend <john.fastabend@gmail.com> Cc: KP Singh <kpsingh@kernel.org> Cc: Martin KaFai Lau <martin.lau@linux.dev> Cc: Song Liu <song@kernel.org> Cc: Stanislav Fomichev <redacted> Cc: Yonghong Song <yonghong.song@linux.dev> Cc: bpf@vger.kernel.org Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> --- net/core/filter.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
diff --git a/net/core/filter.c b/net/core/filter.c
index ba1a739a9bedc..fbcfd563dccfd 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c@@ -1658,9 +1658,12 @@ struct bpf_scratchpad { __be32 diff[MAX_BPF_STACK / sizeof(__be32)]; u8 buff[MAX_BPF_STACK]; }; + local_lock_t bh_lock; }; -static DEFINE_PER_CPU(struct bpf_scratchpad, bpf_sp); +static DEFINE_PER_CPU(struct bpf_scratchpad, bpf_sp) = { + .bh_lock = INIT_LOCAL_LOCK(bh_lock), +}; static inline int __bpf_try_make_writable(struct sk_buff *skb, unsigned int write_len)
@@ -2016,6 +2019,7 @@ BPF_CALL_5(bpf_csum_diff, __be32 *, from, u32, from_size, struct bpf_scratchpad *sp = this_cpu_ptr(&bpf_sp); u32 diff_size = from_size + to_size; int i, j = 0; + __wsum ret; /* This is quite flexible, some examples: *
@@ -2029,12 +2033,15 @@ BPF_CALL_5(bpf_csum_diff, __be32 *, from, u32, from_size, diff_size > sizeof(sp->diff))) return -EINVAL; + local_lock_nested_bh(&bpf_sp.bh_lock); for (i = 0; i < from_size / sizeof(__be32); i++, j++) sp->diff[j] = ~from[i]; for (i = 0; i < to_size / sizeof(__be32); i++, j++) sp->diff[j] = to[i]; - return csum_partial(sp->diff, diff_size, seed); + ret = csum_partial(sp->diff, diff_size, seed); + local_unlock_nested_bh(&bpf_sp.bh_lock); + return ret; } static const struct bpf_func_proto bpf_csum_diff_proto = {
--
2.45.2