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Date: Thu, 26 Aug 2004 16:10:54 +0200
Message-ID: <s5hu0uqkn0x.wl@alsa2.suse.de>
From: Takashi Iwai <tiwai@suse.de>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Cc: Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org,
       thomas@undata.org
Subject: Re: [PATCH] Fix shared interrupt handling of SA_INTERRUPT and SA_SAMPLE_RANDOM
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At Thu, 26 Aug 2004 15:04:04 +0100,
Russell King wrote:
> 
> On Thu, Aug 26, 2004 at 02:50:52PM +0200, Takashi Iwai wrote:
> > At Wed, 25 Aug 2004 13:41:12 -0700,
> > Andrew Morton wrote:
> > > 
> > > Takashi Iwai <tiwai@suse.de> wrote:
> > > >
> > > > Anyway, suppressing the unnecessary call of add_interrupt_randomness()
> > > >  should be still valid.  The reduced patch is below.
> > (snip)
> > > 
> > > Shouldn't that be `if (ret == IRQ_HANDLED)'?
> > 
> > Yes, it's more strict.
> 
> I don't think so.  Look at what's going on.  If "ret" is IRQ_HANDLED
> all well and fine.  However, look at how "retval" is being used:
> 
> static void __report_bad_irq(int irq, irq_desc_t *desc, irqreturn_t action_ret)
> {
> ...
>         if (action_ret != IRQ_HANDLED && action_ret != IRQ_NONE) {
>                 printk(KERN_ERR "irq event %d: bogus return value %x\n",
>                                 irq, action_ret);
>         } else {
>                 printk(KERN_ERR "irq %d: nobody cared!\n", irq);
>         }
> 
> So, we're looking to see not only if a handler returned IRQ_HANDLED,
> but also if a handler returned _some other value_ other than IRQ_HANDLED
> or IRQ_NONE.

But obviously any other value is invalid as shown above, so we
shouldn't take it seriously as the correct return value for
triggering add_random_interrupt().


Takashi