Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754041AbdLTCwY (ORCPT ); Tue, 19 Dec 2017 21:52:24 -0500 Received: from mailgw02.mediatek.com ([210.61.82.184]:33799 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1751559AbdLTCwW (ORCPT ); Tue, 19 Dec 2017 21:52:22 -0500 X-UUID: f774c4d34eef44e08ac9145a70fbf58f-20171220 From: To: , , , , , , , , , CC: , , , , , , Subject: [PATCH] PCI: Mediatek: clear irq status after irq dispathed to avoid reentry Date: Wed, 20 Dec 2017 10:52:14 +0800 Message-ID: <1513738334-26213-1-git-send-email-honghui.zhang@mediatek.com> X-Mailer: git-send-email 2.6.4 MIME-Version: 1.0 Content-Type: text/plain X-MTK: N Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2073 Lines: 57 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 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