netdev - Re: [PATCH bpf-next] bpf: increment and use correct thread iterator

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Message-ID: <20201204015838.inkhwq7nbn2nehsz@ast-mbp>
Date:   Thu, 3 Dec 2020 17:58:38 -0800
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Jonathan Lemon <jonathan.lemon@...il.com>
Cc:     netdev@...r.kernel.org, ast@...nel.org, daniel@...earbox.net,
        yhs@...com, kernel-team@...com
Subject: Re: [PATCH bpf-next] bpf: increment and use correct thread iterator

On Thu, Dec 03, 2020 at 01:59:07PM -0800, Jonathan Lemon wrote:
> From: Jonathan Lemon <bsd@...com>
> 
> If unable to obtain the file structure for the current task,
> proceed to the next task number after the one returned from
> task_seq_get_next(), instead of the next task number from the
> original iterator.
> 
> Use thread_group_leader() instead of comparing tgid vs pid, which
> might may be racy.
> 
> Only obtain the task reference count at the end of the RCU section
> instead of repeatedly obtaining/releasing it when iterathing though
> a thread group.
> 
> This patch fixes a recurring RCU stall seen from task_file_seq_next().
> 
> Fixes: a650da2ee52a ("bpf: Add task and task/file iterator targets")
> Fixes: 67b6b863e6ab ("bpf: Avoid iterating duplicated files for task_file iterator")

There are no such sha-s in bpf-next tree. Pls fix.