From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chuck Ebbert Subject: Re: [proposed patch] via-rhine: prevent oops when requesting an IRQ Date: Mon, 10 Nov 2008 17:28:36 -0500 Message-ID: <20081110172836.0aaec702@redhat.com> References: <20081104192357.2b0dbe22@redhat.com> <491289AD.9070401@garzik.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: Jeff Garzik Return-path: Received: from mx2.redhat.com ([66.187.237.31]:35140 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751827AbYKJW3Y (ORCPT ); Mon, 10 Nov 2008 17:29:24 -0500 In-Reply-To: <491289AD.9070401@garzik.org> Sender: netdev-owner@vger.kernel.org List-ID: On Thu, 06 Nov 2008 01:07:41 -0500 Jeff Garzik wrote: > Chuck Ebbert wrote: > > via-rhine: prevent oops when requesting an IRQ > > > > via-rhine requests an IRQ before it's ready to handle an interrupt. > > It oopses when CONFIG_DEBUG_SHIRQ is enabled. > > > > https://bugzilla.redhat.com/show_bug.cgi?id=469303 > > > > --- > > > > NOTE: UNTESTED: Is it okay to init the hardware before requesting the > > IRQ, or should that be done afterward? > > First of all, _ideally_ your interrupt handler should be able to any > state of software initialization, once registers are mapped. So I would > first concentrate on "hardening" the interrupt handler, if feasible. > > It is certainly a common technique to disable interrupts somehow, during > initialization of the hardware. Note, though, that doing things before > request_irq() is no real guarantee you are out of danger -- you might be > on a shared PCI irq, and your init causes that interrupt to "scream" > even though your driver has not registered the irq. > The problem with this driver is that it doesn't call alloc_ring() before request_irq() and then it oopses in the interrupt handler trying to access the ring.