linux-kernel - Re: [PATCH 15/17] i2c: omap: always return IRQ

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120614112323.GD31187@n2100.arm.linux.org.uk>
Date:	Thu, 14 Jun 2012 12:23:23 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	"Shilimkar, Santosh" <santosh.shilimkar@...com>
Cc:	Felipe Balbi <balbi@...com>, Tony Lindgren <tony@...mide.com>,
	w.sang@...gutronix.de,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-i2c@...r.kernel.org, ben-linux@...ff.org,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	Linux ARM Kernel Mailing List 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 15/17] i2c: omap: always return IRQ_HANDLED

On Thu, Jun 14, 2012 at 04:48:56PM +0530, Shilimkar, Santosh wrote:
> On Thu, Jun 14, 2012 at 3:50 PM, Felipe Balbi <balbi@...com> wrote:
> > otherwise we could get our IRQ line disabled due
> > to many spurious IRQs.
> >
> > Signed-off-by: Felipe Balbi <balbi@...com>
> > ---
> >  drivers/i2c/busses/i2c-omap.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> > index fc5b8bc..5b78a73 100644
> > --- a/drivers/i2c/busses/i2c-omap.c
> > +++ b/drivers/i2c/busses/i2c-omap.c
> > @@ -1015,7 +1015,7 @@ omap_i2c_isr(int this_irq, void *dev_id)
> >                }
> >        } while (stat);
> >
> > -       return count ? IRQ_HANDLED : IRQ_NONE;
> > +       return IRQ_HANDLED;
> 
> no sure if this is correct. if you have IRQ flood and instead of _actually_
> handling it, if you return handled, you still have interrupt pending, right?

The point of returning IRQ_NONE is to indicate to the interrupt layer that
the interrupt you received was not processed by any interrupt handler, and
therefore to provide a way of preventing the system being brought to a halt
though a stuck interrupt line.

So, if you do process an interrupt, you should always return IRQ_HANDLED
even if you couldn't complete its processing (eg, because you've serviced
it 100 times.)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/