Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753564Ab0LLQx5 (ORCPT ); Sun, 12 Dec 2010 11:53:57 -0500 Received: from www.tglx.de ([62.245.132.106]:35056 "EHLO www.tglx.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751500Ab0LLQxx (ORCPT ); Sun, 12 Dec 2010 11:53:53 -0500 Date: Sun, 12 Dec 2010 17:53:31 +0100 (CET) From: Thomas Gleixner To: Jan Kiszka cc: Avi Kivity , Marcelo Tosatti , linux-kernel@vger.kernel.org, kvm , Tom Lyon , Alex Williamson , "Michael S. Tsirkin" , Jan Kiszka Subject: Re: [PATCH v2 2/4] genirq: Inform handler about line sharing state In-Reply-To: <664535c6596c0c6bf7024f2608134c90e2093c19.1292152963.git.jan.kiszka@web.de> Message-ID: References: <664535c6596c0c6bf7024f2608134c90e2093c19.1292152963.git.jan.kiszka@web.de> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3061 Lines: 78 On Sun, 12 Dec 2010, Jan Kiszka wrote: > From: Jan Kiszka > > This enabled interrupt handlers to retrieve the current line sharing state via > the new interrupt status word so that they can adapt to it. > > The switch from shared to exclusive is generally uncritical and can thus be > performed on demand. However, preparing a line for shared mode may require > preparational steps of the currently registered handler. It can therefore > request an ahead-of-time notification via IRQF_ADAPTIVE. The notification > consists of an exceptional handler invocation with IRQS_MAKE_SHAREABLE set in > the status word. > > Signed-off-by: Jan Kiszka > --- > include/linux/interrupt.h | 10 ++++++++++ > include/linux/irqdesc.h | 2 ++ > kernel/irq/irqdesc.c | 2 ++ > kernel/irq/manage.c | 44 +++++++++++++++++++++++++++++++++++++++++--- > 4 files changed, 55 insertions(+), 3 deletions(-) > > diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h > index 16cdbbf..c6323a2 100644 > --- a/include/linux/interrupt.h > +++ b/include/linux/interrupt.h > @@ -55,6 +55,7 @@ > * Used by threaded interrupts which need to keep the > * irq line disabled until the threaded handler has been run. > * IRQF_NO_SUSPEND - Do not disable this IRQ during suspend > + * IRQF_ADAPTIVE - Request notification about upcoming interrupt line sharing > * > */ > #define IRQF_DISABLED 0x00000020 > @@ -67,6 +68,7 @@ > #define IRQF_IRQPOLL 0x00001000 > #define IRQF_ONESHOT 0x00002000 > #define IRQF_NO_SUSPEND 0x00004000 > +#define IRQF_ADAPTIVE 0x00008000 > > #define IRQF_TIMER (__IRQF_TIMER | IRQF_NO_SUSPEND) > > @@ -126,6 +128,14 @@ struct irqaction { > > extern irqreturn_t no_action(int cpl, void *dev_id); > > +/* > + * Driver-readable IRQ line status flags: > + * IRQS_SHARED - line is shared between multiple handlers > + * IRQS_MAKE_SHAREABLE - in the process of making an exclusive line shareable > + */ > +#define IRQS_SHARED 0x00000001 > +#define IRQS_MAKE_SHAREABLE 0x00000002 > + > extern unsigned long get_irq_status(unsigned long irq); > > #ifdef CONFIG_GENERIC_HARDIRQS > diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h > index 979c68c..c490e83 100644 > --- a/include/linux/irqdesc.h > +++ b/include/linux/irqdesc.h > @@ -29,6 +29,7 @@ struct timer_rand_state; > * @wait_for_threads: wait queue for sync_irq to wait for threaded handlers > * @dir: /proc/irq/ procfs entry > * @name: flow handler name for /proc/interrupts output > + * @register_lock: protects registration & release, for unshared->shared I think we can make that a global mutex. request/free_irq are not hotpath operations which require a mutex per irq descriptor. Thanks, tglx -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/