netdev - Re: PROBLEM: potential concurrency bug in rhashtable.h

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Message-ID: <a0b1aa08-b8dd-3b41-6c0c-7482e05a9986@gmail.com>
Date:   Thu, 23 Jul 2020 17:34:15 -0700
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        Eric Dumazet <eric.dumazet@...il.com>
Cc:     "Gong, Sishuai" <sishuai@...due.edu>,
        "tgraf@...g.ch" <tgraf@...g.ch>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "Sousa da Fonseca, Pedro Jose" <pfonseca@...due.edu>
Subject: Re: PROBLEM: potential concurrency bug in rhashtable.h



On 7/23/20 5:09 PM, Herbert Xu wrote:
> On Thu, Jul 23, 2020 at 03:32:05PM -0700, Eric Dumazet wrote:
>>
>> Thanks for the report/analysis. 
> 
> Thanks indeed.
> 
>> READ_ONCE() should help here, can you test/submit an official patch ?
> 
> This is basically a hand-rolled RCU access.  So we should instead
> use proper RCU operators if possible.  Let me see what I can do.

Sure, but __rht_ptr() is used with different RCU checks,
I guess a that adding these lockdep conditions will make
a patch more invasive.