linux-kernel - Re: possible deadlock in cma_netdev

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Date:   Thu, 27 Feb 2020 12:46:22 -0400
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Bernard Metzler <BMT@...ich.ibm.com>
Cc:     syzbot <syzbot+55de90ab5f44172b0c90@...kaller.appspotmail.com>,
        chuck.lever@...cle.com, dledford@...hat.com, leon@...nel.org,
        linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
        netdev@...r.kernel.org, parav@...lanox.com,
        syzkaller-bugs@...glegroups.com, willy@...radead.org
Subject: Re: possible deadlock in cma_netdev_callback

On Thu, Feb 27, 2020 at 04:21:21PM +0000, Bernard Metzler wrote:
> 
> >To: "Bernard Metzler" <BMT@...ich.ibm.com>
> >From: "Jason Gunthorpe" <jgg@...pe.ca>
> >Date: 02/27/2020 04:53PM
> >Cc: "syzbot" <syzbot+55de90ab5f44172b0c90@...kaller.appspotmail.com>,
> >chuck.lever@...cle.com, dledford@...hat.com, leon@...nel.org,
> >linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
> >netdev@...r.kernel.org, parav@...lanox.com,
> >syzkaller-bugs@...glegroups.com, willy@...radead.org
> >Subject: [EXTERNAL] Re: possible deadlock in cma_netdev_callback
> >
> >On Thu, Feb 27, 2020 at 10:11:13AM +0000, Bernard Metzler wrote:
> >
> >> Thanks for letting me know! Hmm, we cannot use RCU locks since
> >> we potentially sleep. One solution would be to create a list
> >> of matching interfaces while under lock, unlock and use that
> >> list for calling siw_listen_address() (which may sleep),
> >> right...?
> >
> >Why do you need to iterate over addresses anyhow? Shouldn't the
> >listen
> >just be done with the address the user gave and a BIND DEVICE to the
> >device siw is connected to?
> 
> The user may give a wildcard local address, so we'd have
> to bind to all addresses of that device...

AFAIK a wild card bind using BIND DEVICE works just fine?

Jason