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 <[email protected]>
Cc: Andrii Nakryiko <[email protected]>
Cc: Hao Luo <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: John Fastabend <[email protected]>
Cc: KP Singh <[email protected]>
Cc: Martin KaFai Lau <[email protected]>
Cc: Song Liu <[email protected]>
Cc: Stanislav Fomichev <[email protected]>
Cc: Yonghong Song <[email protected]>
Cc: [email protected]
Signed-off-by: Sebastian Andrzej Siewior <[email protected]>
---
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 = {
--
2.45.1