Date: Sat, 2 Dec 2006 18:40:35 +0000
From: Al Viro <viro@ftp.linux.org.uk>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Matthew Wilcox <matthew@wil.cx>, Linus Torvalds <torvalds@osdl.org>,
       linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC] timers, pointers to functions and type safety
Message-ID: <20061202184035.GL3078@ftp.linux.org.uk>
References: <20061201172149.GC3078@ftp.linux.org.uk> <1165064370.24604.36.camel@localhost.localdomain> <20061202140521.GJ3078@ftp.linux.org.uk> <1165070713.24604.50.camel@localhost.localdomain> <20061202160252.GQ14076@parisc-linux.org> <1165082803.24604.54.camel@localhost.localdomain> <20061202181957.GK3078@ftp.linux.org.uk> <1165084076.24604.56.camel@localhost.localdomain>
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On Sat, Dec 02, 2006 at 07:27:56PM +0100, Thomas Gleixner wrote:
> On Sat, 2006-12-02 at 18:19 +0000, Al Viro wrote:
> > > This is going to make a lot of data structures smaller, when the
> > > timer_list is embedded in the structure itself and for the lot, which
> > > ignores the timer callback argument anyway.
> > 
> > container_of => still lousy type safety.  All over the sodding place.
> 
> Not less than timer->data, where timer data is void *

RTFPosting.  It might be void *, but it's set via SETUP_TIMER which
does type checks before casting to void *.

IOW, I don't want _any_ typecasts/container_of necessary in the code.

Sane variant is

void foo_timer(struct net_device *dev)
{
	...
}

	struct foo_dev *p = netdev_priv(dev);
	SETUP_TIMER(&p->timer, foo_timer, dev);

etc.

With warning generated if foo_timer(dev) would not be type safe.  Without
typecasts.  Without container_of().  Without any bleeding cruft at all.
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