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Subject: Re: [RFC][PATCH] irq_work
From: Huang Ying <ying.huang@intel.com>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>, Ingo Molnar <mingo@elte.hu>,
       "H.PeterA" <"nvin hpa"@zytor.com>,
       "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
       Andi Kleen <andi@firstfloor.org>
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Date: Fri, 25 Jun 2010 17:30:32 +0800
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On Fri, 2010-06-25 at 17:23 +0800, Frederic Weisbecker wrote:
> 2010/6/25 Huang Ying <ying.huang@intel.com>:
> > On Fri, 2010-06-25 at 15:48 +0800, Peter Zijlstra wrote:
> >> On Fri, 2010-06-25 at 10:12 +0800, Huang Ying wrote:
> >> >
> >> > It is better to add "void *data" field in this struct to allow same
> >> > function can be used for multiple struct irq_work.
> >>
> >> No, simply do:
> >>
> >> struct my_foo {
> >>   struct irq_work work;
> >>   /* my extra data */
> >> }
> >>
> >> void my_func(struct irq_work *work)
> >> {
> >>   struct my_foo *foo = container_of(work, struct my_foo, work);
> >>
> >>   /* tada! */
> >> }
> >
> > Yes. This works too. But Adding "void *data" field is helpful if you do
> > not embed struct irq_work into another struct.
>
> 
> That's what makes most sense. If you use work->data to put foo, then
> you can also do the opposite. Now the best is to pick the choice that
> gives you a real type and a typechecking, and not an error-prone and
> obfuscated void *
> 
> This is the way things are made in the kernel. struct work_struct, struct list,
> struct rcu_head, etc... are all embedded into a container, so that we can
> use container_of.

container_of has no full type checking too.

Best Regards,
Huang Ying