linux-kernel - Re: [PATCH next] netlink: prevent deadlock in ctrl

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Message-ID: <20130820193117.GA2239@swordfish>
Date:	Tue, 20 Aug 2013 22:31:17 +0300
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	"Berg, Johannes" <johannes.berg@...el.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Patrick McHardy <kaber@...sh.net>,
	Pablo Neira Ayuso <pablo@...filter.org>,
	Gao feng <gaofeng@...fujitsu.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH next] netlink: prevent deadlock in ctrl_dumpfamily()

On (08/20/13 14:03), Berg, Johannes wrote:
> > +	if (need_locking) {
> > +		/* genl_mutex could be already locked in genl_rcv_msg() */
> > +		rt = genl_family_find_byid(cb->nlh->nlmsg_type);
> > +		need_locking = need_locking && rt->parallel_ops;
> > +	}
> 
> This is equivalent to reverting the patch because parallel_ops will be false for the genl family. :-)
>

sorry, didn't notice that there is already a thread on lkml regarding
this issue. will follow that discussion. the reason was that I see an
actual deadlock on my machine during certain network activities, but
lockdep is silent.

thanks,
	-ss

> johannes
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