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Date: Sun, 28 Jun 2009 23:48:46 +0200
From: Jarek Poplawski <jarkao2@gmail.com>
To: Oleg Nesterov <oleg@redhat.com>
Cc: Davide Libenzi <davidel@xmailserver.org>,
       Eric Dumazet <eric.dumazet@gmail.com>, Jiri Olsa <jolsa@redhat.com>,
       netdev@vger.kernel.org,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       fbl@redhat.com, nhorman@redhat.com, davem@redhat.com,
       Tejun Heo <htejun@gmail.com>
Subject: Re: [PATCH] net: fix race in the receive/select
Message-ID: <20090628214846.GB4584@ami.dom.local>
References: <4A442B65.8040701@gmail.com> <alpine.DEB.1.10.0906251858520.9517@makko.or.mcafeemobile.com> <4A443033.8060401@gmail.com> <alpine.DEB.1.10.0906251947530.9517@makko.or.mcafeemobile.com> <20090626135742.GB3845@redhat.com> <alpine.DEB.1.10.0906261018580.16400@makko.or.mcafeemobile.com> <20090626145027.GA6534@redhat.com> <4A474FB5.4070901@gmail.com> <4A475266.9040203@gmail.com> <20090628180412.GA9171@redhat.com>
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On Sun, Jun 28, 2009 at 08:04:12PM +0200, Oleg Nesterov wrote:
> On 06/28, Jarek Poplawski wrote:
...
> > Hmm... of course:
> >
> > static inline void sock_poll_wait(struct file * filp, struct sock *sk, poll_table *p)
> > {
> >  	if (p && sk->sk_sleep) {
> >  		__poll_wait(filp, sk->sk_sleep, p);
> >  		/*
> >  		 * fat comment
> >  		 */
> >  		smp_mb(); // or smp_mb__after_unlock();
> >  	}
> > }
> 
> Perhaps it makes sense to check ->sk_sleep != NULL in sock_poll_wait(), but
> I don't think we need __poll_wait(). poll_wait() is inline, I think gcc
> will optimize out "if (p && wait_address)" check if poll_wait() is called
> from sock_poll_wait().

Sure, to me it looks a bit more readable, but let Jiri choose.;-)

Cheers,
Jarek P. 
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