Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757169AbdLUAwr (ORCPT ); Wed, 20 Dec 2017 19:52:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:33104 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756134AbdLUAwp (ORCPT ); Wed, 20 Dec 2017 19:52:45 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 42290218CA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=helgaas@kernel.org Date: Wed, 20 Dec 2017 18:52:41 -0600 From: Bjorn Helgaas To: honghui.zhang@mediatek.com Cc: bhelgaas@google.com, matthias.bgg@gmail.com, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, yingjoe.chen@mediatek.com, eddie.huang@mediatek.com, ryder.lee@mediatek.com, youlin.pei@mediatek.com, hongkun.cao@mediatek.com, sean.wang@mediatek.com, xinping.qian@mediatek.com, yt.shen@mediatek.com, yong.wu@mediatek.com, Lorenzo Pieralisi Subject: Re: [PATCH] PCI: Mediatek: clear irq status after irq dispathed to avoid reentry Message-ID: <20171221005240.GC30595@bhelgaas-glaptop.roam.corp.google.com> References: <1513738334-26213-1-git-send-email-honghui.zhang@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1513738334-26213-1-git-send-email-honghui.zhang@mediatek.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2905 Lines: 80 [+cc Lorenzo, please cc him on all drivers/{host,dwc,endpoint} material] Please run "git log --oneline drivers/pci/host/pcie-mediatek.c" and make yours match. Same capitalization, same sentence structure, etc., e.g., PCI: mediatek: Clear IRQ status ... s/dispathed/dispatched/ s/irq/IRQ/ in the summary and all the English text below. On Wed, Dec 20, 2017 at 10:52:14AM +0800, honghui.zhang@mediatek.com wrote: > From: Honghui Zhang > > There maybe a same irq reentry scenario after irq received in current > irq handle flow: > EP device PCIe host driver EP driver > 1. issue an irq > 2. received irq > 3. clear irq status > 4. dispatch irq > 5. clear irq source > The irq status was not successfully cleared at step 2 since the irq > source was not cleared yet. So the PCIe host driver may receive the > same irq after step 5. Then there's an irq reentry occurred. > Even worse, if the reentry irq was not an irq that EP driver expected, > it may not handle the irq. Then we may run into the dead loop from By "dead loop" I assume you mean "infinite loop"? I don't think it's a deadlock since nothing is waiting. > step 2 to step 4. > Clear the irq status after irq have been dispatched to avoid the irq > reentry. > > Signed-off-by: Honghui Zhang > --- > drivers/pci/host/pcie-mediatek.c | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/pci/host/pcie-mediatek.c b/drivers/pci/host/pcie-mediatek.c > index db93efd..3248771 100644 > --- a/drivers/pci/host/pcie-mediatek.c > +++ b/drivers/pci/host/pcie-mediatek.c > @@ -605,11 +605,11 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) > > while ((status = readl(port->base + PCIE_INT_STATUS)) & INTX_MASK) { > for_each_set_bit_from(bit, &status, PCI_NUM_INTX + INTX_SHIFT) { > - /* Clear the INTx */ > - writel(1 << bit, port->base + PCIE_INT_STATUS); > virq = irq_find_mapping(port->irq_domain, > bit - INTX_SHIFT); > generic_handle_irq(virq); > + /* Clear the INTx */ > + writel(1 << bit, port->base + PCIE_INT_STATUS); > } > } > > @@ -619,10 +619,10 @@ static irqreturn_t mtk_pcie_intr_handler(int irq, void *data) > > while ((imsi_status = readl(port->base + PCIE_IMSI_STATUS))) { > for_each_set_bit(bit, &imsi_status, MTK_MSI_IRQS_NUM) { > - /* Clear the MSI */ > - writel(1 << bit, port->base + PCIE_IMSI_STATUS); > virq = irq_find_mapping(port->msi_domain, bit); > generic_handle_irq(virq); > + /* Clear the MSI */ > + writel(1 << bit, port->base + PCIE_IMSI_STATUS); > } > } > /* Clear MSI interrupt status */ > -- > 2.6.4 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel