Re: [PATCH bpf-next v2 3/8] bpf, iter: Fix the condition on p when calling stop.

From: Yosry Ahmed <yosryahmed@google.com>
To: Yonghong Song <yhs@fb.com>
Cc: Hao Luo <haoluo@google.com>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
	John Fastabend <john.fastabend@gmail.com>,
	KP Singh <kpsingh@kernel.org>, Tejun Heo <tj@kernel.org>,
	Zefan Li <lizefan.x@bytedance.com>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Shuah Khan <shuah@kernel.org>, Michal Hocko <mhocko@kernel.org>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	David Rientjes <rientjes@google.com>,
	Stanislav Fomichev <sdf@google.com>,
	Greg Thelen <gthelen@google.com>,
	Shakeel Butt <shakeelb@google.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	Cgroups <cgroups@vger.kernel.org>
Subject: Re: [PATCH bpf-next v2 3/8] bpf, iter: Fix the condition on p when calling stop.
Date: Fri, 24 Jun 2022 11:23:51 -0700	[thread overview]
Message-ID: <CAJD7tkYX4OLnVZE5KM3J4cLSoU+gMuiSf4_ViYu_FJzq5xwOXg@mail.gmail.com> (raw)
In-Reply-To: <dc5aca8d-16c4-a1fd-a2f1-fd3008c10e02@fb.com>

On Fri, Jun 24, 2022 at 10:46 AM Yonghong Song <yhs@fb.com> wrote:
>
>
>
> On 6/21/22 12:25 AM, Hao Luo wrote:
> > On Mon, Jun 20, 2022 at 11:48 AM Yonghong Song <yhs@fb.com> wrote:
> >>
> >> On 6/10/22 12:44 PM, Yosry Ahmed wrote:
> >>> From: Hao Luo <haoluo@google.com>
> >>>
> >>> In bpf_seq_read, seq->op->next() could return an ERR and jump to
> >>> the label stop. However, the existing code in stop does not handle
> >>> the case when p (returned from next()) is an ERR. Adds the handling
> >>> of ERR of p by converting p into an error and jumping to done.
> >>>
> >>> Because all the current implementations do not have a case that
> >>> returns ERR from next(), so this patch doesn't have behavior changes
> >>> right now.
> >>>
> >>> Signed-off-by: Hao Luo <haoluo@google.com>
> >>> Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
> >>
> >> Acked-by: Yonghong Song <yhs@fb.com>
> >
> > Yonghong, do you want to get this change in now, or you want to wait
> > for the whole patchset? This fix is straightforward and independent of
> > other parts. Yosry and I can rebase.
>
> Sorry for delay. Let me review other patches as well before your next
> version.

Thanks!

>
> BTW, I would be great if you just put the prerequisite patch

I am intending to do that in the next version if KP's patchset doesn't
land in bpf-next.

>
> https://lore.kernel.org/bpf/20220421140740.459558-5-benjamin.tissoires@redhat.com/
> as the first patch so at least BPF CI will be able to test
> your patch set. It looks like KP's bpf_getxattr patch set already did this.
>
> https://lore.kernel.org/bpf/20220624045636.3668195-2-kpsingh@kernel.org/T/#u
>