netdev - Re: [PATCH v1 bpf-next 03/10] bpf: tcp: Get rid of st_bucket

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Message-ID: <wxqtnfk2nkwfd3lybyyitawusswohp7hkaoszfxpfdsiuluilr@g3zlc3ojxjkv>
Date: Thu, 22 May 2025 11:16:13 -0700
From: Jordan Rife <jordan@...fe.io>
To: Kuniyuki Iwashima <kuniyu@...zon.com>
Cc: alexei.starovoitov@...il.com, bpf@...r.kernel.org, 
	daniel@...earbox.net, martin.lau@...ux.dev, netdev@...r.kernel.org, 
	willemdebruijn.kernel@...il.com
Subject: Re: [PATCH v1 bpf-next 03/10] bpf: tcp: Get rid of st_bucket_done

> > >  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.

Jordan