On 5/22/25 1:42 PM, Kuniyuki Iwashima wrote:
From: Jordan Rife <jordan@xxxxxxxx>
Date: Thu, 22 May 2025 11:16:13 -0700
static void bpf_iter_tcp_put_batch(struct bpf_tcp_iter_state *iter)
{
- while (iter->cur_sk < iter->end_sk)
- sock_gen_put(iter->batch[iter->cur_sk++]);
+ unsigned int cur_sk = iter->cur_sk;
+
+ while (cur_sk < iter->end_sk)
+ sock_gen_put(iter->batch[cur_sk++]);
Why is this chunk included in this patch ?
This should be in patch 5 to keep cur_sk for find_cookie
Without this, iter->cur_sk is mutated when iteration stops, and we lose
our place. When iteration resumes and we call bpf_iter_tcp_batch the
iter->cur_sk == iter->end_sk condition will always be true, so we will
skip to the next bucket without seeking to the offset.
Before, we relied on st_bucket_done to tell us if we had remaining items
in the current bucket to process but now need to preserve iter->cur_sk
through iterations to make the behavior equivalent to what we had before.
Thanks for explanation, I was confused by calling tcp_seek_last_pos()
multiple times, and I think we need to preserve/restore st->offset too
in patch 2 and need this change.
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index ac00015d5e7a..0816f20bfdff 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2791,6 +2791,7 @@ static void *tcp_seek_last_pos(struct seq_file *seq)
break;
st->bucket = 0;
st->state = TCP_SEQ_STATE_ESTABLISHED;
+ offset = 0;
This seems like an existing bug not necessarily related to this set.
The patch 5 has also removed the tcp_seek_last_pos() dependency, so I think it
can be a standalone fix on its own.
fallthrough;
case TCP_SEQ_STATE_ESTABLISHED:
if (st->bucket > hinfo->ehash_mask)>
Let's say we are resuming at an offset (10) in the last lhash bucket
but a few sockets (3) disappeared, then we go to the ehash part with
a non-zero offset (3), which will overwrite st->offset (3).
If the ehash does not fit into the batch size, we need to allocate
a new batch and retry, but the offset (3) is different from the
first try (10).
