Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934037Ab2JLNDo (ORCPT ); Fri, 12 Oct 2012 09:03:44 -0400 Received: from mga14.intel.com ([143.182.124.37]:47089 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933185Ab2JLNDn convert rfc822-to-8bit (ORCPT ); Fri, 12 Oct 2012 09:03:43 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.80,576,1344236400"; d="scan'208";a="155500402" From: "Liu, Chuansheng" To: Thomas Gleixner CC: "linux-kernel@vger.kernel.org" Subject: RE: [PATCH] genirq: for edge interrupt IRQS_ONESHOT support with irq thread Thread-Topic: [PATCH] genirq: for edge interrupt IRQS_ONESHOT support with irq thread Thread-Index: AQHNqHeaj1yQox4Me0+UyZJ6nHY31pe1n4TQ Date: Fri, 12 Oct 2012 13:03:39 +0000 Message-ID: <27240C0AC20F114CBF8149A2696CBE4A1958B9@SHSMSX101.ccr.corp.intel.com> References: <1350045084.13178.19.camel@cliu38-desktop-build> <27240C0AC20F114CBF8149A2696CBE4A19587A@SHSMSX101.ccr.corp.intel.com> In-Reply-To: Accept-Language: zh-CN, en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.239.127.40] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3210 Lines: 88 > -----Original Message----- > From: Thomas Gleixner [mailto:tglx@linutronix.de] > Sent: Friday, October 12, 2012 8:46 PM > To: Liu, Chuansheng > Cc: linux-kernel@vger.kernel.org > Subject: RE: [PATCH] genirq: for edge interrupt IRQS_ONESHOT support with irq > thread > > On Fri, 12 Oct 2012, Liu, Chuansheng wrote: > > > -----Original Message----- > > > From: Thomas Gleixner [mailto:tglx@linutronix.de] > > > Sent: Friday, October 12, 2012 8:32 PM > > > To: Liu, Chuansheng > > > Cc: linux-kernel@vger.kernel.org > > > Subject: Re: [PATCH] genirq: for edge interrupt IRQS_ONESHOT support > with irq > > > thread > > > > > > On Fri, 12 Oct 2012, Chuansheng Liu wrote: > > > > > > > > In our system, there is one edge interrupt, and we want it to be > > > > irq thread with IRQS_ONESHOT, and found in handle_edge_irq(), > > > > even with IRQS_ONESHOT, the irq is still unmasked without care of > > > > flag IRQS_ONESHOT. > > > > > > > > It causes IRQS_ONESHOT can not work well for edge interrupt, but also > > > > after the irq thread finished with flag IRQS_ONESHOT, the irq will be > > > > possible to be unmasked again, it should be messing mask/unmask logic. > > > > > > This is just wrong. By masking edge interrupts you will run into > > > situations where you will lose interrupts. > > > > > > Can you please explain, why you want to mask your edge interrupt? > > > When I request_irq with irq thread handler and flag IRQS_ONESHOT, if > > do not mask the edge interrupt, the primary handler and irq thread > > maybe run at the same time, and in my real case it causes spin > > deadlock. > > Then your code is simply wrong and you need to fix it instead of hacking a > workaround into the core code. Locking is not that hard. I got means, so I want to use flag IRQS_ONESHOT to avoid the case that two handlers running at the same time. Is it right direction? But IRQS_ONESHOT does not work well for edge interrupt. And pasting the IRQS_ONESHOT description: * IRQS_ONESHOT - irq is not unmasked in primary handler And I need irq handler is because some heavy work is needed, it can avoid local irq disabling time thru irq handler. > > > You means it is not right with IRQS_ONESHOT for edge interrupt? > > It's wrong. Simnply because you can lose interrupts. > > interrupt raised > handle_edge_irq() > mask_ack_irq() > handle_event() > wake irq thread > reti > > irq thread runs > handle device interrupt() > <--- device issues edge irq > unmask_irq() > > This interrupt is not delivered. So your device stops working. Not > what you want, right? Device should not stop:) And even in current handle_edge_irq(), it is possible that losting Interrupt if primary handler need some time and the irq is quick enough. I says the below code, it just avoid one time lost. desc->istate |= IRQS_PENDING; mask_ack_irq(desc); > > 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/