linux-kernel - Re: [patch v2] epoll use a single inode ...

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Message-ID: <Pine.LNX.4.64.0703051609430.4907@alien.or.mcafeemobile.com>
Date:	Mon, 5 Mar 2007 16:12:12 -0800 (PST)
From:	Davide Libenzi <davidel@...ilserver.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Eric Dumazet <dada1@...mosbay.com>
Subject: Re: [patch v2] epoll use a single inode ...

On Mon, 5 Mar 2007, Linus Torvalds wrote:

> On Mon, 5 Mar 2007, Davide Libenzi wrote:
> > @@ -763,15 +767,17 @@
> >  	 * using the inode number.
> >  	 */
> >  	error = -ENOMEM;
> > -	sprintf(name, "[%lu]", inode->i_ino);
> >  	this.name = name;
> > -	this.len = strlen(name);
> > -	this.hash = inode->i_ino;
> > +	this.len = sprintf(name, "[%p]", ep);
> > +	this.hash = 0;
> 
> Please don't expose kernel pointers to user space.
> 
> It's much better to do something like
> 
> 	static unsigned int epoll_inode;
> 
> 	this.len = sprintf(name, "[%u]", ++epoll_inode);
> 
> if you just need some pseudo-unique name to distinguish two epoll things 
> from each other (vs from a dup'ed fd).

Heh, this is what Al was saying ;)
I'm fine with that, but how about counter cycles (going back to zero)? 
Should we care to handle them correctly? 



- Davide


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