netdev - Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap

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Date:   Tue, 5 Feb 2019 19:40:18 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Alexei Starovoitov <alexei.starovoitov@...il.com>
Cc:     Waiman Long <longman@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Alexei Starovoitov <ast@...nel.org>, davem@...emloft.net,
        daniel@...earbox.net, edumazet@...gle.com, jannh@...gle.com,
        netdev@...r.kernel.org, kernel-team@...com, songliubraving@...com
Subject: Re: [PATCH bpf-next 2/4] bpf: fix lockdep false positive in stackmap



On 02/05/2019 07:30 PM, Alexei Starovoitov wrote:

> Thanks for the reminder :)
> 
> I've been waiting for Peter's direction on this one.
> Happy to fix it whichever way.
> 
> To recap:
> Approach 1:
> s/up_read/up_read_non_owner/ from irq_work + rwsem_release as Longman proposed.
> 
> Apporach 2:
> introduce down_read_trylock_non_owner and pair it with up_read_non_owner
> in both irq_work and normal.
> 
> My preference is 1. I think Longman's as well.
> 


Unless we envision other uses for down_read_trylock_non_owner() and up_read_non_owner(),
I agree 1) seems good enough, at least for the short term.

Thanks !